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module ActiveRecord
class HasManyThroughAssociationNotFoundError < ActiveRecordError #:nodoc:
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def initialize ( owner_class_name , reflection )
super ( " Could not find the association #{ reflection . options [ :through ] . inspect } in model #{ owner_class_name } " )
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end
end
class HasManyThroughAssociationPolymorphicError < ActiveRecordError #:nodoc:
def initialize ( owner_class_name , reflection , source_reflection )
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super ( " Cannot have a has_many :through association ' #{ owner_class_name } # #{ reflection . name } ' on the polymorphic object ' #{ source_reflection . class_name } # #{ source_reflection . name } '. " )
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end
end
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class HasManyThroughAssociationPointlessSourceTypeError < ActiveRecordError #:nodoc:
def initialize ( owner_class_name , reflection , source_reflection )
super ( " Cannot have a has_many :through association ' #{ owner_class_name } # #{ reflection . name } ' with a :source_type option if the ' #{ reflection . through_reflection . class_name } # #{ source_reflection . name } ' is not polymorphic. Try removing :source_type on your association. " )
end
end
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class HasManyThroughSourceAssociationNotFoundError < ActiveRecordError #:nodoc:
def initialize ( reflection )
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through_reflection = reflection . through_reflection
source_reflection_names = reflection . source_reflection_names
source_associations = reflection . through_reflection . klass . reflect_on_all_associations . collect { | a | a . name . inspect }
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super ( " Could not find the source association(s) #{ source_reflection_names . collect ( & :inspect ) . to_sentence ( :two_words_connector = > ' or ' , :last_word_connector = > ', or ' , :locale = > :en ) } in model #{ through_reflection . klass } . Try 'has_many #{ reflection . name . inspect } , :through => #{ through_reflection . name . inspect } , :source => <name>'. Is it one of #{ source_associations . to_sentence ( :two_words_connector = > ' or ' , :last_word_connector = > ', or ' , :locale = > :en ) } ? " )
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end
end
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class HasManyThroughSourceAssociationMacroError < ActiveRecordError #:nodoc:
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def initialize ( reflection )
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through_reflection = reflection . through_reflection
source_reflection = reflection . source_reflection
super ( " Invalid source reflection macro : #{ source_reflection . macro } #{ " :through " if source_reflection . options [ :through ] } for has_many #{ reflection . name . inspect } , :through => #{ through_reflection . name . inspect } . Use :source to specify the source reflection. " )
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end
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end
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class HasManyThroughCantAssociateThroughHasManyReflection < ActiveRecordError #:nodoc:
def initialize ( owner , reflection )
super ( " Cannot modify association ' #{ owner . class . name } # #{ reflection . name } ' because the source reflection class ' #{ reflection . source_reflection . class_name } ' is associated to ' #{ reflection . through_reflection . class_name } ' via : #{ reflection . source_reflection . macro } . " )
end
end
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class HasManyThroughCantAssociateNewRecords < ActiveRecordError #:nodoc:
def initialize ( owner , reflection )
super ( " Cannot associate new records through ' #{ owner . class . name } # #{ reflection . name } ' on ' #{ reflection . source_reflection . class_name rescue nil } # #{ reflection . source_reflection . name rescue nil } '. Both records must have an id in order to create the has_many :through record associating them. " )
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end
end
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class HasManyThroughCantDissociateNewRecords < ActiveRecordError #:nodoc:
def initialize ( owner , reflection )
super ( " Cannot dissociate new records through ' #{ owner . class . name } # #{ reflection . name } ' on ' #{ reflection . source_reflection . class_name rescue nil } # #{ reflection . source_reflection . name rescue nil } '. Both records must have an id in order to delete the has_many :through record associating them. " )
end
end
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class HasAndBelongsToManyAssociationForeignKeyNeeded < ActiveRecordError #:nodoc:
def initialize ( reflection )
super ( " Cannot create self referential has_and_belongs_to_many association on ' #{ reflection . class_name rescue nil } # #{ reflection . name rescue nil } '. :association_foreign_key cannot be the same as the :foreign_key. " )
end
end
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class EagerLoadPolymorphicError < ActiveRecordError #:nodoc:
def initialize ( reflection )
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super ( " Can not eagerly load the polymorphic association #{ reflection . name . inspect } " )
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end
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end
class ReadOnlyAssociation < ActiveRecordError #:nodoc:
def initialize ( reflection )
super ( " Can not add to a has_many :through association. Try adding to #{ reflection . through_reflection . name . inspect } . " )
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end
end
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# See ActiveRecord::Associations::ClassMethods for documentation.
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module Associations # :nodoc:
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# These classes will be loaded when associations are created.
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# So there is no need to eager load them.
autoload :AssociationCollection , 'active_record/associations/association_collection'
autoload :AssociationProxy , 'active_record/associations/association_proxy'
autoload :BelongsToAssociation , 'active_record/associations/belongs_to_association'
autoload :BelongsToPolymorphicAssociation , 'active_record/associations/belongs_to_polymorphic_association'
autoload :HasAndBelongsToManyAssociation , 'active_record/associations/has_and_belongs_to_many_association'
autoload :HasManyAssociation , 'active_record/associations/has_many_association'
autoload :HasManyThroughAssociation , 'active_record/associations/has_many_through_association'
autoload :HasOneAssociation , 'active_record/associations/has_one_association'
autoload :HasOneThroughAssociation , 'active_record/associations/has_one_through_association'
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def self . included ( base )
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base . extend ( ClassMethods )
end
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# Clears out the association cache
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def clear_association_cache #:nodoc:
self . class . reflect_on_all_associations . to_a . each do | assoc |
instance_variable_set " @ #{ assoc . name } " , nil
end unless self . new_record?
end
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private
# Gets the specified association instance if it responds to :loaded?, nil otherwise.
def association_instance_get ( name )
association = instance_variable_get ( " @ #{ name } " )
association if association . respond_to? ( :loaded? )
end
# Set the specified association instance.
def association_instance_set ( name , association )
instance_variable_set ( " @ #{ name } " , association )
end
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# Associations are a set of macro-like class methods for tying objects together through foreign keys. They express relationships like
# "Project has one Project Manager" or "Project belongs to a Portfolio". Each macro adds a number of methods to the class which are
# specialized according to the collection or association symbol and the options hash. It works much the same way as Ruby's own <tt>attr*</tt>
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# methods. Example:
#
# class Project < ActiveRecord::Base
# belongs_to :portfolio
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# has_one :project_manager
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# has_many :milestones
# has_and_belongs_to_many :categories
# end
#
# The project class now has the following methods (and more) to ease the traversal and manipulation of its relationships:
# * <tt>Project#portfolio, Project#portfolio=(portfolio), Project#portfolio.nil?</tt>
# * <tt>Project#project_manager, Project#project_manager=(project_manager), Project#project_manager.nil?,</tt>
# * <tt>Project#milestones.empty?, Project#milestones.size, Project#milestones, Project#milestones<<(milestone),</tt>
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# <tt>Project#milestones.delete(milestone), Project#milestones.find(milestone_id), Project#milestones.find(:all, options),</tt>
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# <tt>Project#milestones.build, Project#milestones.create</tt>
# * <tt>Project#categories.empty?, Project#categories.size, Project#categories, Project#categories<<(category1),</tt>
# <tt>Project#categories.delete(category1)</tt>
#
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# === A word of warning
#
# Don't create associations that have the same name as instance methods of ActiveRecord::Base. Since the association
# adds a method with that name to its model, it will override the inherited method and break things.
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# For instance, +attributes+ and +connection+ would be bad choices for association names.
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#
# == Auto-generated methods
#
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# === Singular associations (one-to-one)
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# | | belongs_to |
# generated methods | belongs_to | :polymorphic | has_one
# ----------------------------------+------------+--------------+---------
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# other | X | X | X
# other=(other) | X | X | X
# build_other(attributes={}) | X | | X
# create_other(attributes={}) | X | | X
# other.create!(attributes={}) | | | X
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#
# ===Collection associations (one-to-many / many-to-many)
# | | | has_many
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# generated methods | habtm | has_many | :through
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# ----------------------------------+-------+----------+----------
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# others | X | X | X
# others=(other,other,...) | X | X | X
# other_ids | X | X | X
# other_ids=(id,id,...) | X | X | X
# others<< | X | X | X
# others.push | X | X | X
# others.concat | X | X | X
# others.build(attributes={}) | X | X | X
# others.create(attributes={}) | X | X | X
# others.create!(attributes={}) | X | X | X
# others.size | X | X | X
# others.length | X | X | X
# others.count | X | X | X
# others.sum(args*,&block) | X | X | X
# others.empty? | X | X | X
# others.clear | X | X | X
# others.delete(other,other,...) | X | X | X
# others.delete_all | X | X |
# others.destroy_all | X | X | X
# others.find(*args) | X | X | X
# others.find_first | X | |
# others.exists? | X | X | X
# others.uniq | X | X | X
# others.reset | X | X | X
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#
# == Cardinality and associations
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#
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# Active Record associations can be used to describe one-to-one, one-to-many and many-to-many
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# relationships between models. Each model uses an association to describe its role in
# the relation. The +belongs_to+ association is always used in the model that has
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# the foreign key.
#
# === One-to-one
#
# Use +has_one+ in the base, and +belongs_to+ in the associated model.
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#
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# class Employee < ActiveRecord::Base
# has_one :office
# end
# class Office < ActiveRecord::Base
# belongs_to :employee # foreign key - employee_id
# end
#
# === One-to-many
#
# Use +has_many+ in the base, and +belongs_to+ in the associated model.
#
# class Manager < ActiveRecord::Base
# has_many :employees
# end
# class Employee < ActiveRecord::Base
# belongs_to :manager # foreign key - manager_id
# end
#
# === Many-to-many
#
# There are two ways to build a many-to-many relationship.
#
# The first way uses a +has_many+ association with the <tt>:through</tt> option and a join model, so
# there are two stages of associations.
#
# class Assignment < ActiveRecord::Base
# belongs_to :programmer # foreign key - programmer_id
# belongs_to :project # foreign key - project_id
# end
# class Programmer < ActiveRecord::Base
# has_many :assignments
# has_many :projects, :through => :assignments
# end
# class Project < ActiveRecord::Base
# has_many :assignments
# has_many :programmers, :through => :assignments
# end
#
# For the second way, use +has_and_belongs_to_many+ in both models. This requires a join table
# that has no corresponding model or primary key.
#
# class Programmer < ActiveRecord::Base
# has_and_belongs_to_many :projects # foreign keys in the join table
# end
# class Project < ActiveRecord::Base
# has_and_belongs_to_many :programmers # foreign keys in the join table
# end
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#
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# Choosing which way to build a many-to-many relationship is not always simple.
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# If you need to work with the relationship model as its own entity,
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# use <tt>has_many :through</tt>. Use +has_and_belongs_to_many+ when working with legacy schemas or when
# you never work directly with the relationship itself.
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#
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# == Is it a +belongs_to+ or +has_one+ association?
#
# Both express a 1-1 relationship. The difference is mostly where to place the foreign key, which goes on the table for the class
# declaring the +belongs_to+ relationship. Example:
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#
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# class User < ActiveRecord::Base
# # I reference an account.
# belongs_to :account
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# end
#
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# class Account < ActiveRecord::Base
# # One user references me.
# has_one :user
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# end
#
# The tables for these classes could look something like:
#
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# CREATE TABLE users (
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# id int(11) NOT NULL auto_increment,
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# account_id int(11) default NULL,
# name varchar default NULL,
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# PRIMARY KEY (id)
# )
#
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# CREATE TABLE accounts (
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# id int(11) NOT NULL auto_increment,
# name varchar default NULL,
# PRIMARY KEY (id)
# )
#
# == Unsaved objects and associations
#
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# You can manipulate objects and associations before they are saved to the database, but there is some special behavior you should be
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# aware of, mostly involving the saving of associated objects.
#
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# Unless you enable the :autosave option on a <tt>has_one</tt>, <tt>belongs_to</tt>,
# <tt>has_many</tt>, or <tt>has_and_belongs_to_many</tt> association,
# in which case the members are always saved.
#
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# === One-to-one associations
#
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# * Assigning an object to a +has_one+ association automatically saves that object and the object being replaced (if there is one), in
# order to update their primary keys - except if the parent object is unsaved (<tt>new_record? == true</tt>).
# * If either of these saves fail (due to one of the objects being invalid) the assignment statement returns +false+ and the assignment
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# is cancelled.
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# * If you wish to assign an object to a +has_one+ association without saving it, use the <tt>association.build</tt> method (documented below).
# * Assigning an object to a +belongs_to+ association does not save the object, since the foreign key field belongs on the parent. It
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# does not save the parent either.
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#
# === Collections
#
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# * Adding an object to a collection (+has_many+ or +has_and_belongs_to_many+) automatically saves that object, except if the parent object
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# (the owner of the collection) is not yet stored in the database.
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# * If saving any of the objects being added to a collection (via <tt>push</tt> or similar) fails, then <tt>push</tt> returns +false+.
# * You can add an object to a collection without automatically saving it by using the <tt>collection.build</tt> method (documented below).
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# * All unsaved (<tt>new_record? == true</tt>) members of the collection are automatically saved when the parent is saved.
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#
# === Association callbacks
#
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# Similar to the normal callbacks that hook into the lifecycle of an Active Record object, you can also define callbacks that get
# triggered when you add an object to or remove an object from an association collection. Example:
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#
# class Project
# has_and_belongs_to_many :developers, :after_add => :evaluate_velocity
#
# def evaluate_velocity(developer)
# ...
# end
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# end
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#
# It's possible to stack callbacks by passing them as an array. Example:
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#
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# class Project
# has_and_belongs_to_many :developers, :after_add => [:evaluate_velocity, Proc.new { |p, d| p.shipping_date = Time.now}]
# end
#
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# Possible callbacks are: +before_add+, +after_add+, +before_remove+ and +after_remove+.
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#
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# Should any of the +before_add+ callbacks throw an exception, the object does not get added to the collection. Same with
# the +before_remove+ callbacks; if an exception is thrown the object doesn't get removed.
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#
# === Association extensions
#
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# The proxy objects that control the access to associations can be extended through anonymous modules. This is especially
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# beneficial for adding new finders, creators, and other factory-type methods that are only used as part of this association.
# Example:
#
# class Account < ActiveRecord::Base
# has_many :people do
# def find_or_create_by_name(name)
# first_name, last_name = name.split(" ", 2)
# find_or_create_by_first_name_and_last_name(first_name, last_name)
# end
# end
# end
#
# person = Account.find(:first).people.find_or_create_by_name("David Heinemeier Hansson")
# person.first_name # => "David"
# person.last_name # => "Heinemeier Hansson"
#
# If you need to share the same extensions between many associations, you can use a named extension module. Example:
#
# module FindOrCreateByNameExtension
# def find_or_create_by_name(name)
# first_name, last_name = name.split(" ", 2)
# find_or_create_by_first_name_and_last_name(first_name, last_name)
# end
# end
#
# class Account < ActiveRecord::Base
# has_many :people, :extend => FindOrCreateByNameExtension
# end
#
# class Company < ActiveRecord::Base
# has_many :people, :extend => FindOrCreateByNameExtension
# end
#
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# If you need to use multiple named extension modules, you can specify an array of modules with the <tt>:extend</tt> option.
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# In the case of name conflicts between methods in the modules, methods in modules later in the array supercede
# those earlier in the array. Example:
#
# class Account < ActiveRecord::Base
# has_many :people, :extend => [FindOrCreateByNameExtension, FindRecentExtension]
# end
#
# Some extensions can only be made to work with knowledge of the association proxy's internals.
# Extensions can access relevant state using accessors on the association proxy:
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#
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# * +proxy_owner+ - Returns the object the association is part of.
# * +proxy_reflection+ - Returns the reflection object that describes the association.
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# * +proxy_target+ - Returns the associated object for +belongs_to+ and +has_one+, or the collection of associated objects for +has_many+ and +has_and_belongs_to_many+.
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#
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# === Association Join Models
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#
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# Has Many associations can be configured with the <tt>:through</tt> option to use an explicit join model to retrieve the data. This
# operates similarly to a +has_and_belongs_to_many+ association. The advantage is that you're able to add validations,
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# callbacks, and extra attributes on the join model. Consider the following schema:
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#
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# class Author < ActiveRecord::Base
# has_many :authorships
# has_many :books, :through => :authorships
# end
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#
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# class Authorship < ActiveRecord::Base
# belongs_to :author
# belongs_to :book
# end
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#
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# @author = Author.find :first
# @author.authorships.collect { |a| a.book } # selects all books that the author's authorships belong to.
# @author.books # selects all books by using the Authorship join model
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#
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# You can also go through a +has_many+ association on the join model:
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#
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# class Firm < ActiveRecord::Base
# has_many :clients
# has_many :invoices, :through => :clients
# end
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#
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# class Client < ActiveRecord::Base
# belongs_to :firm
# has_many :invoices
# end
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#
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# class Invoice < ActiveRecord::Base
# belongs_to :client
# end
#
# @firm = Firm.find :first
# @firm.clients.collect { |c| c.invoices }.flatten # select all invoices for all clients of the firm
# @firm.invoices # selects all invoices by going through the Client join model.
#
# === Polymorphic Associations
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#
# Polymorphic associations on models are not restricted on what types of models they can be associated with. Rather, they
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# specify an interface that a +has_many+ association must adhere to.
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#
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# class Asset < ActiveRecord::Base
# belongs_to :attachable, :polymorphic => true
# end
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#
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# class Post < ActiveRecord::Base
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# has_many :assets, :as => :attachable # The :as option specifies the polymorphic interface to use.
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# end
#
# @asset.attachable = @post
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#
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# This works by using a type column in addition to a foreign key to specify the associated record. In the Asset example, you'd need
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# an +attachable_id+ integer column and an +attachable_type+ string column.
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#
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# Using polymorphic associations in combination with single table inheritance (STI) is a little tricky. In order
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# for the associations to work as expected, ensure that you store the base model for the STI models in the
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# type column of the polymorphic association. To continue with the asset example above, suppose there are guest posts
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# and member posts that use the posts table for STI. In this case, there must be a +type+ column in the posts table.
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#
# class Asset < ActiveRecord::Base
# belongs_to :attachable, :polymorphic => true
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#
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# def attachable_type=(sType)
# super(sType.to_s.classify.constantize.base_class.to_s)
# end
# end
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#
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# class Post < ActiveRecord::Base
# # because we store "Post" in attachable_type now :dependent => :destroy will work
# has_many :assets, :as => :attachable, :dependent => :destroy
# end
#
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# class GuestPost < Post
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# end
#
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# class MemberPost < Post
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# end
#
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# == Caching
#
# All of the methods are built on a simple caching principle that will keep the result of the last query around unless specifically
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# instructed not to. The cache is even shared across methods to make it even cheaper to use the macro-added methods without
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# worrying too much about performance at the first go. Example:
#
# project.milestones # fetches milestones from the database
# project.milestones.size # uses the milestone cache
# project.milestones.empty? # uses the milestone cache
# project.milestones(true).size # fetches milestones from the database
# project.milestones # uses the milestone cache
#
# == Eager loading of associations
#
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# Eager loading is a way to find objects of a certain class and a number of named associations. This is
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# one of the easiest ways of to prevent the dreaded 1+N problem in which fetching 100 posts that each need to display their author
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# triggers 101 database queries. Through the use of eager loading, the 101 queries can be reduced to 2. Example:
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#
# class Post < ActiveRecord::Base
# belongs_to :author
# has_many :comments
# end
#
# Consider the following loop using the class above:
#
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# for post in Post.all
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# puts "Post: " + post.title
# puts "Written by: " + post.author.name
# puts "Last comment on: " + post.comments.first.created_on
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# end
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#
# To iterate over these one hundred posts, we'll generate 201 database queries. Let's first just optimize it for retrieving the author:
#
# for post in Post.find(:all, :include => :author)
#
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# This references the name of the +belongs_to+ association that also used the <tt>:author</tt> symbol. After loading the posts, find
# will collect the +author_id+ from each one and load all the referenced authors with one query. Doing so will cut down the number of queries from 201 to 102.
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#
# We can improve upon the situation further by referencing both associations in the finder with:
#
# for post in Post.find(:all, :include => [ :author, :comments ])
#
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# This will load all comments with a single query. This reduces the total number of queries to 3. More generally the number of queries
# will be 1 plus the number of associations named (except if some of the associations are polymorphic +belongs_to+ - see below).
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#
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# To include a deep hierarchy of associations, use a hash:
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#
# for post in Post.find(:all, :include => [ :author, { :comments => { :author => :gravatar } } ])
#
# That'll grab not only all the comments but all their authors and gravatar pictures. You can mix and match
# symbols, arrays and hashes in any combination to describe the associations you want to load.
#
# All of this power shouldn't fool you into thinking that you can pull out huge amounts of data with no performance penalty just because you've reduced
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# the number of queries. The database still needs to send all the data to Active Record and it still needs to be processed. So it's no
# catch-all for performance problems, but it's a great way to cut down on the number of queries in a situation as the one described above.
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#
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# Since only one table is loaded at a time, conditions or orders cannot reference tables other than the main one. If this is the case
# Active Record falls back to the previously used LEFT OUTER JOIN based strategy. For example
#
# Post.find(:all, :include => [ :author, :comments ], :conditions => ['comments.approved = ?', true])
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#
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# will result in a single SQL query with joins along the lines of: <tt>LEFT OUTER JOIN comments ON comments.post_id = posts.id</tt> and
# <tt>LEFT OUTER JOIN authors ON authors.id = posts.author_id</tt>. Note that using conditions like this can have unintended consequences.
# In the above example posts with no approved comments are not returned at all, because the conditions apply to the SQL statement as a whole
# and not just to the association. You must disambiguate column references for this fallback to happen, for example
# <tt>:order => "author.name DESC"</tt> will work but <tt>:order => "name DESC"</tt> will not.
#
# If you do want eagerload only some members of an association it is usually more natural to <tt>:include</tt> an association
# which has conditions defined on it:
#
# class Post < ActiveRecord::Base
# has_many :approved_comments, :class_name => 'Comment', :conditions => ['approved = ?', true]
# end
#
# Post.find(:all, :include => :approved_comments)
#
# will load posts and eager load the +approved_comments+ association, which contains only those comments that have been approved.
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#
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# If you eager load an association with a specified <tt>:limit</tt> option, it will be ignored, returning all the associated objects:
#
# class Picture < ActiveRecord::Base
# has_many :most_recent_comments, :class_name => 'Comment', :order => 'id DESC', :limit => 10
# end
#
# Picture.find(:first, :include => :most_recent_comments).most_recent_comments # => returns all associated comments.
#
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# When eager loaded, conditions are interpolated in the context of the model class, not the model instance. Conditions are lazily interpolated
# before the actual model exists.
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#
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# Eager loading is supported with polymorphic associations.
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#
# class Address < ActiveRecord::Base
# belongs_to :addressable, :polymorphic => true
# end
#
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# A call that tries to eager load the addressable model
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#
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# Address.find(:all, :include => :addressable)
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#
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# will execute one query to load the addresses and load the addressables with one query per addressable type.
# For example if all the addressables are either of class Person or Company then a total of 3 queries will be executed. The list of
# addressable types to load is determined on the back of the addresses loaded. This is not supported if Active Record has to fallback
# to the previous implementation of eager loading and will raise ActiveRecord::EagerLoadPolymorphicError. The reason is that the parent
# model's type is a column value so its corresponding table name cannot be put in the +FROM+/+JOIN+ clauses of that query.
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#
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# == Table Aliasing
#
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# Active Record uses table aliasing in the case that a table is referenced multiple times in a join. If a table is referenced only once,
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# the standard table name is used. The second time, the table is aliased as <tt>#{reflection_name}_#{parent_table_name}</tt>. Indexes are appended
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# for any more successive uses of the table name.
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#
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# Post.find :all, :joins => :comments
# # => SELECT ... FROM posts INNER JOIN comments ON ...
# Post.find :all, :joins => :special_comments # STI
# # => SELECT ... FROM posts INNER JOIN comments ON ... AND comments.type = 'SpecialComment'
# Post.find :all, :joins => [:comments, :special_comments] # special_comments is the reflection name, posts is the parent table name
# # => SELECT ... FROM posts INNER JOIN comments ON ... INNER JOIN comments special_comments_posts
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#
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# Acts as tree example:
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#
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# TreeMixin.find :all, :joins => :children
# # => SELECT ... FROM mixins INNER JOIN mixins childrens_mixins ...
# TreeMixin.find :all, :joins => {:children => :parent}
# # => SELECT ... FROM mixins INNER JOIN mixins childrens_mixins ...
# INNER JOIN parents_mixins ...
# TreeMixin.find :all, :joins => {:children => {:parent => :children}}
# # => SELECT ... FROM mixins INNER JOIN mixins childrens_mixins ...
# INNER JOIN parents_mixins ...
# INNER JOIN mixins childrens_mixins_2
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#
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# Has and Belongs to Many join tables use the same idea, but add a <tt>_join</tt> suffix:
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#
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# Post.find :all, :joins => :categories
# # => SELECT ... FROM posts INNER JOIN categories_posts ... INNER JOIN categories ...
# Post.find :all, :joins => {:categories => :posts}
# # => SELECT ... FROM posts INNER JOIN categories_posts ... INNER JOIN categories ...
# INNER JOIN categories_posts posts_categories_join INNER JOIN posts posts_categories
# Post.find :all, :joins => {:categories => {:posts => :categories}}
# # => SELECT ... FROM posts INNER JOIN categories_posts ... INNER JOIN categories ...
# INNER JOIN categories_posts posts_categories_join INNER JOIN posts posts_categories
# INNER JOIN categories_posts categories_posts_join INNER JOIN categories categories_posts_2
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#
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# If you wish to specify your own custom joins using a <tt>:joins</tt> option, those table names will take precedence over the eager associations:
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#
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# Post.find :all, :joins => :comments, :joins => "inner join comments ..."
# # => SELECT ... FROM posts INNER JOIN comments_posts ON ... INNER JOIN comments ...
# Post.find :all, :joins => [:comments, :special_comments], :joins => "inner join comments ..."
# # => SELECT ... FROM posts INNER JOIN comments comments_posts ON ...
# INNER JOIN comments special_comments_posts ...
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# INNER JOIN comments ...
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#
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# Table aliases are automatically truncated according to the maximum length of table identifiers according to the specific database.
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#
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# == Modules
#
# By default, associations will look for objects within the current module scope. Consider:
#
# module MyApplication
# module Business
# class Firm < ActiveRecord::Base
# has_many :clients
# end
#
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# class Client < ActiveRecord::Base; end
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# end
# end
#
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# When <tt>Firm#clients</tt> is called, it will in turn call <tt>MyApplication::Business::Client.find_all_by_firm_id(firm.id)</tt>.
# If you want to associate with a class in another module scope, this can be done by specifying the complete class name.
# Example:
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#
# module MyApplication
# module Business
# class Firm < ActiveRecord::Base; end
# end
#
# module Billing
# class Account < ActiveRecord::Base
# belongs_to :firm, :class_name => "MyApplication::Business::Firm"
# end
# end
# end
#
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# == Type safety with <tt>ActiveRecord::AssociationTypeMismatch</tt>
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#
# If you attempt to assign an object to an association that doesn't match the inferred or specified <tt>:class_name</tt>, you'll
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# get an <tt>ActiveRecord::AssociationTypeMismatch</tt>.
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#
# == Options
#
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# All of the association macros can be specialized through options. This makes cases more complex than the simple and guessable ones
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# possible.
module ClassMethods
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# Specifies a one-to-many association. The following methods for retrieval and query of
# collections of associated objects will be added:
#
# [collection(force_reload = false)]
# Returns an array of all the associated objects.
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# An empty array is returned if none are found.
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# [collection<<(object, ...)]
# Adds one or more objects to the collection by setting their foreign keys to the collection's primary key.
# [collection.delete(object, ...)]
# Removes one or more objects from the collection by setting their foreign keys to +NULL+.
# Objects will be in addition destroyed if they're associated with <tt>:dependent => :destroy</tt>,
# and deleted if they're associated with <tt>:dependent => :delete_all</tt>.
# [collection=objects]
# Replaces the collections content by deleting and adding objects as appropriate.
# [collection_singular_ids]
# Returns an array of the associated objects' ids
# [collection_singular_ids=ids]
# Replace the collection with the objects identified by the primary keys in +ids+
# [collection.clear]
# Removes every object from the collection. This destroys the associated objects if they
# are associated with <tt>:dependent => :destroy</tt>, deletes them directly from the
# database if <tt>:dependent => :delete_all</tt>, otherwise sets their foreign keys to +NULL+.
# [collection.empty?]
# Returns +true+ if there are no associated objects.
# [collection.size]
# Returns the number of associated objects.
# [collection.find(...)]
# Finds an associated object according to the same rules as ActiveRecord::Base.find.
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# [collection.exists?(...)]
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# Checks whether an associated object with the given conditions exists.
# Uses the same rules as ActiveRecord::Base.exists?.
# [collection.build(attributes = {}, ...)]
# Returns one or more new objects of the collection type that have been instantiated
# with +attributes+ and linked to this object through a foreign key, but have not yet
# been saved. <b>Note:</b> This only works if an associated object already exists, not if
# it's +nil+!
# [collection.create(attributes = {})]
# Returns a new object of the collection type that has been instantiated
# with +attributes+, linked to this object through a foreign key, and that has already
# been saved (if it passed the validation). <b>Note:</b> This only works if an associated
# object already exists, not if it's +nil+!
#
# (*Note*: +collection+ is replaced with the symbol passed as the first argument, so
# <tt>has_many :clients</tt> would add among others <tt>clients.empty?</tt>.)
#
# === Example
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#
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# Example: A Firm class declares <tt>has_many :clients</tt>, which will add:
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# * <tt>Firm#clients</tt> (similar to <tt>Clients.find :all, :conditions => ["firm_id = ?", id]</tt>)
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# * <tt>Firm#clients<<</tt>
# * <tt>Firm#clients.delete</tt>
# * <tt>Firm#clients=</tt>
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# * <tt>Firm#client_ids</tt>
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# * <tt>Firm#client_ids=</tt>
# * <tt>Firm#clients.clear</tt>
# * <tt>Firm#clients.empty?</tt> (similar to <tt>firm.clients.size == 0</tt>)
# * <tt>Firm#clients.size</tt> (similar to <tt>Client.count "firm_id = #{id}"</tt>)
# * <tt>Firm#clients.find</tt> (similar to <tt>Client.find(id, :conditions => "firm_id = #{id}")</tt>)
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# * <tt>Firm#clients.exists?(:name => 'ACME')</tt> (similar to <tt>Client.exists?(:name => 'ACME', :firm_id => firm.id)</tt>)
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# * <tt>Firm#clients.build</tt> (similar to <tt>Client.new("firm_id" => id)</tt>)
# * <tt>Firm#clients.create</tt> (similar to <tt>c = Client.new("firm_id" => id); c.save; c</tt>)
# The declaration can also include an options hash to specialize the behavior of the association.
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#
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# === Supported options
# [:class_name]
# Specify the class name of the association. Use it only if that name can't be inferred
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# from the association name. So <tt>has_many :products</tt> will by default be linked to the Product class, but
# if the real class name is SpecialProduct, you'll have to specify it with this option.
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# [:conditions]
# Specify the conditions that the associated objects must meet in order to be included as a +WHERE+
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# SQL fragment, such as <tt>price > 5 AND name LIKE 'B%'</tt>. Record creations from the association are scoped if a hash
# is used. <tt>has_many :posts, :conditions => {:published => true}</tt> will create published posts with <tt>@blog.posts.create</tt>
# or <tt>@blog.posts.build</tt>.
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# [:order]
# Specify the order in which the associated objects are returned as an <tt>ORDER BY</tt> SQL fragment,
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# such as <tt>last_name, first_name DESC</tt>.
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# [:foreign_key]
# Specify the foreign key used for the association. By default this is guessed to be the name
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# of this class in lower-case and "_id" suffixed. So a Person class that makes a +has_many+ association will use "person_id"
# as the default <tt>:foreign_key</tt>.
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# [:primary_key]
# Specify the method that returns the primary key used for the association. By default this is +id+.
# [:dependent]
# If set to <tt>:destroy</tt> all the associated objects are destroyed
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# alongside this object by calling their +destroy+ method. If set to <tt>:delete_all</tt> all associated
# objects are deleted *without* calling their +destroy+ method. If set to <tt>:nullify</tt> all associated
# objects' foreign keys are set to +NULL+ *without* calling their +save+ callbacks. *Warning:* This option is ignored when also using
# the <tt>:through</tt> option.
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# [:finder_sql]
# Specify a complete SQL statement to fetch the association. This is a good way to go for complex
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# associations that depend on multiple tables. Note: When this option is used, +find_in_collection+ is _not_ added.
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# [:counter_sql]
# Specify a complete SQL statement to fetch the size of the association. If <tt>:finder_sql</tt> is
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# specified but not <tt>:counter_sql</tt>, <tt>:counter_sql</tt> will be generated by replacing <tt>SELECT ... FROM</tt> with <tt>SELECT COUNT(*) FROM</tt>.
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# [:extend]
# Specify a named module for extending the proxy. See "Association extensions".
# [:include]
# Specify second-order associations that should be eager loaded when the collection is loaded.
# [:group]
# An attribute name by which the result should be grouped. Uses the <tt>GROUP BY</tt> SQL-clause.
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# [:having]
# Combined with +:group+ this can be used to filter the records that a <tt>GROUP BY</tt> returns. Uses the <tt>HAVING</tt> SQL-clause.
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# [:limit]
# An integer determining the limit on the number of rows that should be returned.
# [:offset]
# An integer determining the offset from where the rows should be fetched. So at 5, it would skip the first 4 rows.
# [:select]
# By default, this is <tt>*</tt> as in <tt>SELECT * FROM</tt>, but can be changed if you, for example, want to do a join
# but not include the joined columns. Do not forget to include the primary and foreign keys, otherwise it will raise an error.
# [:as]
# Specifies a polymorphic interface (See <tt>belongs_to</tt>).
# [:through]
# Specifies a Join Model through which to perform the query. Options for <tt>:class_name</tt> and <tt>:foreign_key</tt>
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# are ignored, as the association uses the source reflection. You can only use a <tt>:through</tt> query through a <tt>belongs_to</tt>
# or <tt>has_many</tt> association on the join model.
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# [:source]
# Specifies the source association name used by <tt>has_many :through</tt> queries. Only use it if the name cannot be
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# inferred from the association. <tt>has_many :subscribers, :through => :subscriptions</tt> will look for either <tt>:subscribers</tt> or
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# <tt>:subscriber</tt> on Subscription, unless a <tt>:source</tt> is given.
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# [:source_type]
# Specifies type of the source association used by <tt>has_many :through</tt> queries where the source
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# association is a polymorphic +belongs_to+.
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# [:uniq]
# If true, duplicates will be omitted from the collection. Useful in conjunction with <tt>:through</tt>.
# [:readonly]
# If true, all the associated objects are readonly through the association.
# [:validate]
# If false, don't validate the associated objects when saving the parent object. true by default.
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# [:autosave]
# If true, always save any loaded members and destroy members marked for destruction, when saving the parent object. Off by default.
#
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# Option examples:
# has_many :comments, :order => "posted_on"
# has_many :comments, :include => :author
# has_many :people, :class_name => "Person", :conditions => "deleted = 0", :order => "name"
# has_many :tracks, :order => "position", :dependent => :destroy
# has_many :comments, :dependent => :nullify
# has_many :tags, :as => :taggable
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# has_many :reports, :readonly => true
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# has_many :subscribers, :through => :subscriptions, :source => :user
# has_many :subscribers, :class_name => "Person", :finder_sql =>
# 'SELECT DISTINCT people.* ' +
# 'FROM people p, post_subscriptions ps ' +
# 'WHERE ps.post_id = #{id} AND ps.person_id = p.id ' +
# 'ORDER BY p.first_name'
def has_many ( association_id , options = { } , & extension )
reflection = create_has_many_reflection ( association_id , options , & extension )
configure_dependency_for_has_many ( reflection )
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add_association_callbacks ( reflection . name , reflection . options )
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if options [ :through ]
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collection_accessor_methods ( reflection , HasManyThroughAssociation )
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else
collection_accessor_methods ( reflection , HasManyAssociation )
end
end
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# Specifies a one-to-one association with another class. This method should only be used
# if the other class contains the foreign key. If the current class contains the foreign key,
# then you should use +belongs_to+ instead. See also ActiveRecord::Associations::ClassMethods's overview
# on when to use has_one and when to use belongs_to.
#
# The following methods for retrieval and query of a single associated object will be added:
#
# [association(force_reload = false)]
# Returns the associated object. +nil+ is returned if none is found.
# [association=(associate)]
# Assigns the associate object, extracts the primary key, sets it as the foreign key,
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# and saves the associate object.
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# [build_association(attributes = {})]
# Returns a new object of the associated type that has been instantiated
# with +attributes+ and linked to this object through a foreign key, but has not
# yet been saved. <b>Note:</b> This ONLY works if an association already exists.
# It will NOT work if the association is +nil+.
# [create_association(attributes = {})]
# Returns a new object of the associated type that has been instantiated
# with +attributes+, linked to this object through a foreign key, and that
# has already been saved (if it passed the validation).
#
# (+association+ is replaced with the symbol passed as the first argument, so
# <tt>has_one :manager</tt> would add among others <tt>manager.nil?</tt>.)
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#
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# === Example
#
# An Account class declares <tt>has_one :beneficiary</tt>, which will add:
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# * <tt>Account#beneficiary</tt> (similar to <tt>Beneficiary.find(:first, :conditions => "account_id = #{id}")</tt>)
# * <tt>Account#beneficiary=(beneficiary)</tt> (similar to <tt>beneficiary.account_id = account.id; beneficiary.save</tt>)
# * <tt>Account#build_beneficiary</tt> (similar to <tt>Beneficiary.new("account_id" => id)</tt>)
# * <tt>Account#create_beneficiary</tt> (similar to <tt>b = Beneficiary.new("account_id" => id); b.save; b</tt>)
#
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# === Options
#
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# The declaration can also include an options hash to specialize the behavior of the association.
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#
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# Options are:
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# [:class_name]
# Specify the class name of the association. Use it only if that name can't be inferred
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# from the association name. So <tt>has_one :manager</tt> will by default be linked to the Manager class, but
# if the real class name is Person, you'll have to specify it with this option.
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# [:conditions]
# Specify the conditions that the associated object must meet in order to be included as a +WHERE+
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# SQL fragment, such as <tt>rank = 5</tt>.
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# [:order]
# Specify the order in which the associated objects are returned as an <tt>ORDER BY</tt> SQL fragment,
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# such as <tt>last_name, first_name DESC</tt>.
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# [:dependent]
# If set to <tt>:destroy</tt>, the associated object is destroyed when this object is. If set to
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# <tt>:delete</tt>, the associated object is deleted *without* calling its destroy method. If set to <tt>:nullify</tt>, the associated
# object's foreign key is set to +NULL+. Also, association is assigned.
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# [:foreign_key]
# Specify the foreign key used for the association. By default this is guessed to be the name
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# of this class in lower-case and "_id" suffixed. So a Person class that makes a +has_one+ association will use "person_id"
# as the default <tt>:foreign_key</tt>.
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# [:primary_key]
# Specify the method that returns the primary key used for the association. By default this is +id+.
# [:include]
# Specify second-order associations that should be eager loaded when this object is loaded.
# [:as]
# Specifies a polymorphic interface (See <tt>belongs_to</tt>).
# [:select]
# By default, this is <tt>*</tt> as in <tt>SELECT * FROM</tt>, but can be changed if, for example, you want to do a join
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# but not include the joined columns. Do not forget to include the primary and foreign keys, otherwise it will raise an error.
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# [:through]
# Specifies a Join Model through which to perform the query. Options for <tt>:class_name</tt> and <tt>:foreign_key</tt>
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# are ignored, as the association uses the source reflection. You can only use a <tt>:through</tt> query through a
# <tt>has_one</tt> or <tt>belongs_to</tt> association on the join model.
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# [:source]
# Specifies the source association name used by <tt>has_one :through</tt> queries. Only use it if the name cannot be
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# inferred from the association. <tt>has_one :favorite, :through => :favorites</tt> will look for a
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# <tt>:favorite</tt> on Favorite, unless a <tt>:source</tt> is given.
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# [:source_type]
# Specifies type of the source association used by <tt>has_one :through</tt> queries where the source
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# association is a polymorphic +belongs_to+.
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# [:readonly]
# If true, the associated object is readonly through the association.
# [:validate]
# If false, don't validate the associated object when saving the parent object. +false+ by default.
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# [:autosave]
# If true, always save the associated object or destroy it if marked for destruction, when saving the parent object. Off by default.
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#
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# Option examples:
# has_one :credit_card, :dependent => :destroy # destroys the associated credit card
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# has_one :credit_card, :dependent => :nullify # updates the associated records foreign key value to NULL rather than destroying it
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# has_one :last_comment, :class_name => "Comment", :order => "posted_on"
# has_one :project_manager, :class_name => "Person", :conditions => "role = 'project_manager'"
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# has_one :attachment, :as => :attachable
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# has_one :boss, :readonly => :true
# has_one :club, :through => :membership
# has_one :primary_address, :through => :addressables, :conditions => ["addressable.primary = ?", true], :source => :addressable
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def has_one ( association_id , options = { } )
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if options [ :through ]
reflection = create_has_one_through_reflection ( association_id , options )
association_accessor_methods ( reflection , ActiveRecord :: Associations :: HasOneThroughAssociation )
else
reflection = create_has_one_reflection ( association_id , options )
association_accessor_methods ( reflection , HasOneAssociation )
association_constructor_method ( :build , reflection , HasOneAssociation )
association_constructor_method ( :create , reflection , HasOneAssociation )
configure_dependency_for_has_one ( reflection )
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end
end
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# Specifies a one-to-one association with another class. This method should only be used
# if this class contains the foreign key. If the other class contains the foreign key,
# then you should use +has_one+ instead. See also ActiveRecord::Associations::ClassMethods's overview
# on when to use +has_one+ and when to use +belongs_to+.
#
# Methods will be added for retrieval and query for a single associated object, for which
# this object holds an id:
#
# [association(force_reload = false)]
# Returns the associated object. +nil+ is returned if none is found.
# [association=(associate)]
# Assigns the associate object, extracts the primary key, and sets it as the foreign key.
# [build_association(attributes = {})]
# Returns a new object of the associated type that has been instantiated
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# with +attributes+ and linked to this object through a foreign key, but has not yet been saved.
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# [create_association(attributes = {})]
# Returns a new object of the associated type that has been instantiated
# with +attributes+, linked to this object through a foreign key, and that
# has already been saved (if it passed the validation).
#
# (+association+ is replaced with the symbol passed as the first argument, so
# <tt>belongs_to :author</tt> would add among others <tt>author.nil?</tt>.)
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#
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# === Example
#
# A Post class declares <tt>belongs_to :author</tt>, which will add:
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# * <tt>Post#author</tt> (similar to <tt>Author.find(author_id)</tt>)
# * <tt>Post#author=(author)</tt> (similar to <tt>post.author_id = author.id</tt>)
# * <tt>Post#author?</tt> (similar to <tt>post.author == some_author</tt>)
# * <tt>Post#build_author</tt> (similar to <tt>post.author = Author.new</tt>)
# * <tt>Post#create_author</tt> (similar to <tt>post.author = Author.new; post.author.save; post.author</tt>)
# The declaration can also include an options hash to specialize the behavior of the association.
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#
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# === Options
#
# [:class_name]
# Specify the class name of the association. Use it only if that name can't be inferred
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# from the association name. So <tt>has_one :author</tt> will by default be linked to the Author class, but
# if the real class name is Person, you'll have to specify it with this option.
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# [:conditions]
# Specify the conditions that the associated object must meet in order to be included as a +WHERE+
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# SQL fragment, such as <tt>authorized = 1</tt>.
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# [:select]
# By default, this is <tt>*</tt> as in <tt>SELECT * FROM</tt>, but can be changed if, for example, you want to do a join
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# but not include the joined columns. Do not forget to include the primary and foreign keys, otherwise it will raise an error.
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# [:foreign_key]
# Specify the foreign key used for the association. By default this is guessed to be the name
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# of the association with an "_id" suffix. So a class that defines a <tt>belongs_to :person</tt> association will use
# "person_id" as the default <tt>:foreign_key</tt>. Similarly, <tt>belongs_to :favorite_person, :class_name => "Person"</tt>
# will use a foreign key of "favorite_person_id".
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# [:primary_key]
# Specify the method that returns the primary key of associated object used for the association. By default this is id.
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# [:dependent]
# If set to <tt>:destroy</tt>, the associated object is destroyed when this object is. If set to
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# <tt>:delete</tt>, the associated object is deleted *without* calling its destroy method. This option should not be specified when
# <tt>belongs_to</tt> is used in conjunction with a <tt>has_many</tt> relationship on another class because of the potential to leave
# orphaned records behind.
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# [:counter_cache]
# Caches the number of belonging objects on the associate class through the use of +increment_counter+
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# and +decrement_counter+. The counter cache is incremented when an object of this class is created and decremented when it's
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# destroyed. This requires that a column named <tt>#{table_name}_count</tt> (such as +comments_count+ for a belonging Comment class)
# is used on the associate class (such as a Post class). You can also specify a custom counter cache column by providing
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# a column name instead of a +true+/+false+ value to this option (e.g., <tt>:counter_cache => :my_custom_counter</tt>.)
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# Note: Specifying a counter cache will add it to that model's list of readonly attributes using +attr_readonly+.
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# [:include]
# Specify second-order associations that should be eager loaded when this object is loaded.
# [:polymorphic]
# Specify this association is a polymorphic association by passing +true+.
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# Note: If you've enabled the counter cache, then you may want to add the counter cache attribute
# to the +attr_readonly+ list in the associated classes (e.g. <tt>class Post; attr_readonly :comments_count; end</tt>).
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# [:readonly]
# If true, the associated object is readonly through the association.
# [:validate]
# If false, don't validate the associated objects when saving the parent object. +false+ by default.
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# [:autosave]
# If true, always save the associated object or destroy it if marked for destruction, when saving the parent object. Off by default.
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# [:touch]
# If true, the associated object will be touched (the updated_at/on attributes set to now) when this record is either saved or
# destroyed. If you specify a symbol, that attribute will be updated with the current time instead of the updated_at/on attribute.
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#
# Option examples:
# belongs_to :firm, :foreign_key => "client_of"
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# belongs_to :person, :primary_key => "name", :foreign_key => "person_name"
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# belongs_to :author, :class_name => "Person", :foreign_key => "author_id"
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# belongs_to :valid_coupon, :class_name => "Coupon", :foreign_key => "coupon_id",
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# :conditions => 'discounts > #{payments_count}'
# belongs_to :attachable, :polymorphic => true
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# belongs_to :project, :readonly => true
# belongs_to :post, :counter_cache => true
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# belongs_to :company, :touch => true
# belongs_to :company, :touch => :employees_last_updated_at
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def belongs_to ( association_id , options = { } )
reflection = create_belongs_to_reflection ( association_id , options )
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if reflection . options [ :polymorphic ]
association_accessor_methods ( reflection , BelongsToPolymorphicAssociation )
else
association_accessor_methods ( reflection , BelongsToAssociation )
association_constructor_method ( :build , reflection , BelongsToAssociation )
association_constructor_method ( :create , reflection , BelongsToAssociation )
end
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add_counter_cache_callbacks ( reflection ) if options [ :counter_cache ]
add_touch_callbacks ( reflection , options [ :touch ] ) if options [ :touch ]
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configure_dependency_for_belongs_to ( reflection )
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end
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# Specifies a many-to-many relationship with another class. This associates two classes via an
# intermediate join table. Unless the join table is explicitly specified as an option, it is
# guessed using the lexical order of the class names. So a join between Developer and Project
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# will give the default join table name of "developers_projects" because "D" outranks "P". Note that this precedence
# is calculated using the <tt><</tt> operator for String. This means that if the strings are of different lengths,
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# and the strings are equal when compared up to the shortest length, then the longer string is considered of higher
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# lexical precedence than the shorter one. For example, one would expect the tables "paper_boxes" and "papers"
# to generate a join table name of "papers_paper_boxes" because of the length of the name "paper_boxes",
# but it in fact generates a join table name of "paper_boxes_papers". Be aware of this caveat, and use the
# custom <tt>:join_table</tt> option if you need to.
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#
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# The join table should not have a primary key or a model associated with it. You must manually generate the
# join table with a migration such as this:
#
# class CreateDevelopersProjectsJoinTable < ActiveRecord::Migration
# def self.up
# create_table :developers_projects, :id => false do |t|
# t.integer :developer_id
# t.integer :project_id
# end
# end
#
# def self.down
# drop_table :developers_projects
# end
# end
#
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# Deprecated: Any additional fields added to the join table will be placed as attributes when pulling records out through
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# +has_and_belongs_to_many+ associations. Records returned from join tables with additional attributes will be marked as
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# readonly (because we can't save changes to the additional attributes). It's strongly recommended that you upgrade any
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# associations with attributes to a real join model (see introduction).
#
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# Adds the following methods for retrieval and query:
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#
# [collection(force_reload = false)]
# Returns an array of all the associated objects.
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# An empty array is returned if none are found.
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# [collection<<(object, ...)]
# Adds one or more objects to the collection by creating associations in the join table
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# (<tt>collection.push</tt> and <tt>collection.concat</tt> are aliases to this method).
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# [collection.delete(object, ...)]
# Removes one or more objects from the collection by removing their associations from the join table.
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# This does not destroy the objects.
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# [collection=objects]
# Replaces the collection's content by deleting and adding objects as appropriate.
# [collection_singular_ids]
# Returns an array of the associated objects' ids.
# [collection_singular_ids=ids]
# Replace the collection by the objects identified by the primary keys in +ids+.
# [collection.clear]
# Removes every object from the collection. This does not destroy the objects.
# [collection.empty?]
# Returns +true+ if there are no associated objects.
# [collection.size]
# Returns the number of associated objects.
# [collection.find(id)]
# Finds an associated object responding to the +id+ and that
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# meets the condition that it has to be associated with this object.
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# Uses the same rules as ActiveRecord::Base.find.
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# [collection.exists?(...)]
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# Checks whether an associated object with the given conditions exists.
# Uses the same rules as ActiveRecord::Base.exists?.
# [collection.build(attributes = {})]
# Returns a new object of the collection type that has been instantiated
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# with +attributes+ and linked to this object through the join table, but has not yet been saved.
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# [collection.create(attributes = {})]
# Returns a new object of the collection type that has been instantiated
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# with +attributes+, linked to this object through the join table, and that has already been saved (if it passed the validation).
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#
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# (+collection+ is replaced with the symbol passed as the first argument, so
# <tt>has_and_belongs_to_many :categories</tt> would add among others <tt>categories.empty?</tt>.)
#
# === Example
#
# A Developer class declares <tt>has_and_belongs_to_many :projects</tt>, which will add:
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# * <tt>Developer#projects</tt>
# * <tt>Developer#projects<<</tt>
# * <tt>Developer#projects.delete</tt>
# * <tt>Developer#projects=</tt>
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# * <tt>Developer#project_ids</tt>
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# * <tt>Developer#project_ids=</tt>
# * <tt>Developer#projects.clear</tt>
# * <tt>Developer#projects.empty?</tt>
# * <tt>Developer#projects.size</tt>
# * <tt>Developer#projects.find(id)</tt>
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# * <tt>Developer#clients.exists?(...)</tt>
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# * <tt>Developer#projects.build</tt> (similar to <tt>Project.new("project_id" => id)</tt>)
# * <tt>Developer#projects.create</tt> (similar to <tt>c = Project.new("project_id" => id); c.save; c</tt>)
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# The declaration may include an options hash to specialize the behavior of the association.
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#
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# === Options
#
# [:class_name]
# Specify the class name of the association. Use it only if that name can't be inferred
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# from the association name. So <tt>has_and_belongs_to_many :projects</tt> will by default be linked to the
# Project class, but if the real class name is SuperProject, you'll have to specify it with this option.
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# [:join_table]
# Specify the name of the join table if the default based on lexical order isn't what you want.
# <b>WARNING:</b> If you're overwriting the table name of either class, the +table_name+ method
# MUST be declared underneath any +has_and_belongs_to_many+ declaration in order to work.
# [:foreign_key]
# Specify the foreign key used for the association. By default this is guessed to be the name
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# of this class in lower-case and "_id" suffixed. So a Person class that makes a +has_and_belongs_to_many+ association
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# to Project will use "person_id" as the default <tt>:foreign_key</tt>.
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# [:association_foreign_key]
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# Specify the foreign key used for the association on the receiving side of the association.
# By default this is guessed to be the name of the associated class in lower-case and "_id" suffixed.
# So if a Person class makes a +has_and_belongs_to_many+ association to Project,
# the association will use "project_id" as the default <tt>:association_foreign_key</tt>.
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# [:conditions]
# Specify the conditions that the associated object must meet in order to be included as a +WHERE+
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# SQL fragment, such as <tt>authorized = 1</tt>. Record creations from the association are scoped if a hash is used.
# <tt>has_many :posts, :conditions => {:published => true}</tt> will create published posts with <tt>@blog.posts.create</tt>
# or <tt>@blog.posts.build</tt>.
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# [:order]
# Specify the order in which the associated objects are returned as an <tt>ORDER BY</tt> SQL fragment,
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# such as <tt>last_name, first_name DESC</tt>
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# [:uniq]
# If true, duplicate associated objects will be ignored by accessors and query methods.
# [:finder_sql]
# Overwrite the default generated SQL statement used to fetch the association with a manual statement
# [:counter_sql]
# Specify a complete SQL statement to fetch the size of the association. If <tt>:finder_sql</tt> is
# specified but not <tt>:counter_sql</tt>, <tt>:counter_sql</tt> will be generated by replacing <tt>SELECT ... FROM</tt> with <tt>SELECT COUNT(*) FROM</tt>.
# [:delete_sql]
# Overwrite the default generated SQL statement used to remove links between the associated
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# classes with a manual statement.
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# [:insert_sql]
# Overwrite the default generated SQL statement used to add links between the associated classes
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# with a manual statement.
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# [:extend]
# Anonymous module for extending the proxy, see "Association extensions".
# [:include]
# Specify second-order associations that should be eager loaded when the collection is loaded.
# [:group]
# An attribute name by which the result should be grouped. Uses the <tt>GROUP BY</tt> SQL-clause.
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# [:having]
# Combined with +:group+ this can be used to filter the records that a <tt>GROUP BY</tt> returns. Uses the <tt>HAVING</tt> SQL-clause.
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# [:limit]
# An integer determining the limit on the number of rows that should be returned.
# [:offset]
# An integer determining the offset from where the rows should be fetched. So at 5, it would skip the first 4 rows.
# [:select]
# By default, this is <tt>*</tt> as in <tt>SELECT * FROM</tt>, but can be changed if, for example, you want to do a join
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# but not include the joined columns. Do not forget to include the primary and foreign keys, otherwise it will raise an error.
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# [:readonly]
# If true, all the associated objects are readonly through the association.
# [:validate]
# If false, don't validate the associated objects when saving the parent object. +true+ by default.
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# [:autosave]
# If true, always save any loaded members and destroy members marked for destruction, when saving the parent object. Off by default.
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#
# Option examples:
# has_and_belongs_to_many :projects
# has_and_belongs_to_many :projects, :include => [ :milestones, :manager ]
# has_and_belongs_to_many :nations, :class_name => "Country"
# has_and_belongs_to_many :categories, :join_table => "prods_cats"
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# has_and_belongs_to_many :categories, :readonly => true
# has_and_belongs_to_many :active_projects, :join_table => 'developers_projects', :delete_sql =>
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# 'DELETE FROM developers_projects WHERE active=1 AND developer_id = #{id} AND project_id = #{record.id}'
def has_and_belongs_to_many ( association_id , options = { } , & extension )
reflection = create_has_and_belongs_to_many_reflection ( association_id , options , & extension )
collection_accessor_methods ( reflection , HasAndBelongsToManyAssociation )
# Don't use a before_destroy callback since users' before_destroy
# callbacks will be executed after the association is wiped out.
old_method = " destroy_without_habtm_shim_for_ #{ reflection . name } "
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class_eval <<-end_eval unless method_defined?(old_method)
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alias_method : #{old_method}, :destroy_without_callbacks # alias_method :destroy_without_habtm_shim_for_posts, :destroy_without_callbacks
def destroy_without_callbacks # def destroy_without_callbacks
#{reflection.name}.clear # posts.clear
#{old_method} # destroy_without_habtm_shim_for_posts
end # end
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end_eval
add_association_callbacks ( reflection . name , options )
end
private
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# Generates a join table name from two provided table names.
# The names in the join table namesme end up in lexicographic order.
#
# join_table_name("members", "clubs") # => "clubs_members"
# join_table_name("members", "special_clubs") # => "members_special_clubs"
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def join_table_name ( first_table_name , second_table_name )
if first_table_name < second_table_name
join_table = " #{ first_table_name } _ #{ second_table_name } "
else
join_table = " #{ second_table_name } _ #{ first_table_name } "
end
table_name_prefix + join_table + table_name_suffix
end
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def association_accessor_methods ( reflection , association_proxy_class )
define_method ( reflection . name ) do | * params |
force_reload = params . first unless params . empty?
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association = association_instance_get ( reflection . name )
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if association . nil? || force_reload
association = association_proxy_class . new ( self , reflection )
retval = association . reload
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if retval . nil? and association_proxy_class == BelongsToAssociation
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association_instance_set ( reflection . name , nil )
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return nil
end
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association_instance_set ( reflection . name , association )
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end
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association . target . nil? ? nil : association
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end
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define_method ( " loaded_ #{ reflection . name } ? " ) do
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association = association_instance_get ( reflection . name )
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association && association . loaded?
end
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define_method ( " #{ reflection . name } = " ) do | new_value |
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association = association_instance_get ( reflection . name )
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if association . nil? || association . target != new_value
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association = association_proxy_class . new ( self , reflection )
end
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if association_proxy_class == HasOneThroughAssociation
association . create_through_record ( new_value )
self . send ( reflection . name , new_value )
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else
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association . replace ( new_value )
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association_instance_set ( reflection . name , new_value . nil? ? nil : association )
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end
end
define_method ( " set_ #{ reflection . name } _target " ) do | target |
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return if target . nil? and association_proxy_class == BelongsToAssociation
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association = association_proxy_class . new ( self , reflection )
association . target = target
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association_instance_set ( reflection . name , association )
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end
end
def collection_reader_method ( reflection , association_proxy_class )
define_method ( reflection . name ) do | * params |
force_reload = params . first unless params . empty?
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association = association_instance_get ( reflection . name )
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unless association
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association = association_proxy_class . new ( self , reflection )
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association_instance_set ( reflection . name , association )
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end
association . reload if force_reload
association
end
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define_method ( " #{ reflection . name . to_s . singularize } _ids " ) do
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if send ( reflection . name ) . loaded? || reflection . options [ :finder_sql ]
send ( reflection . name ) . map ( & :id )
else
send ( reflection . name ) . all ( :select = > " #{ reflection . quoted_table_name } . #{ reflection . klass . primary_key } " ) . map ( & :id )
end
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end
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end
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def collection_accessor_methods ( reflection , association_proxy_class , writer = true )
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collection_reader_method ( reflection , association_proxy_class )
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if writer
define_method ( " #{ reflection . name } = " ) do | new_value |
# Loads proxy class instance (defined in collection_reader_method) if not already loaded
association = send ( reflection . name )
association . replace ( new_value )
association
end
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define_method ( " #{ reflection . name . to_s . singularize } _ids= " ) do | new_value |
ids = ( new_value || [ ] ) . reject { | nid | nid . blank? }
send ( " #{ reflection . name } = " , reflection . class_name . constantize . find ( ids ) )
end
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end
end
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def association_constructor_method ( constructor , reflection , association_proxy_class )
define_method ( " #{ constructor } _ #{ reflection . name } " ) do | * params |
attributees = params . first unless params . empty?
replace_existing = params [ 1 ] . nil? ? true : params [ 1 ]
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association = association_instance_get ( reflection . name )
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unless association
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association = association_proxy_class . new ( self , reflection )
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association_instance_set ( reflection . name , association )
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end
if association_proxy_class == HasOneAssociation
association . send ( constructor , attributees , replace_existing )
else
association . send ( constructor , attributees )
end
end
end
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def add_counter_cache_callbacks ( reflection )
cache_column = reflection . counter_cache_column
method_name = " belongs_to_counter_cache_after_create_for_ #{ reflection . name } " . to_sym
define_method ( method_name ) do
association = send ( reflection . name )
association . class . increment_counter ( cache_column , association . id ) unless association . nil?
end
after_create ( method_name )
method_name = " belongs_to_counter_cache_before_destroy_for_ #{ reflection . name } " . to_sym
define_method ( method_name ) do
association = send ( reflection . name )
association . class . decrement_counter ( cache_column , association . id ) unless association . nil?
end
before_destroy ( method_name )
module_eval (
" #{ reflection . class_name } .send(:attr_readonly, \" #{ cache_column } \" .intern) if defined?( #{ reflection . class_name } ) && #{ reflection . class_name } .respond_to?(:attr_readonly) "
)
end
def add_touch_callbacks ( reflection , touch_attribute )
method_name = " belongs_to_touch_after_save_or_destroy_for_ #{ reflection . name } " . to_sym
define_method ( method_name ) do
association = send ( reflection . name )
if touch_attribute == true
association . touch unless association . nil?
else
association . touch ( touch_attribute ) unless association . nil?
end
end
after_save ( method_name )
after_destroy ( method_name )
end
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def find_with_associations ( options = { } )
catch :invalid_query do
join_dependency = JoinDependency . new ( self , merge_includes ( scope ( :find , :include ) , options [ :include ] ) , options [ :joins ] )
rows = select_all_rows ( options , join_dependency )
return join_dependency . instantiate ( rows )
end
[ ]
end
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# Creates before_destroy callback methods that nullify, delete or destroy
# has_many associated objects, according to the defined :dependent rule.
#
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# See HasManyAssociation#delete_records. Dependent associations
# delete children, otherwise foreign key is set to NULL.
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#
# The +extra_conditions+ parameter, which is not used within the main
# Active Record codebase, is meant to allow plugins to define extra
# finder conditions.
def configure_dependency_for_has_many ( reflection , extra_conditions = nil )
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if reflection . options . include? ( :dependent )
# Add polymorphic type if the :as option is present
dependent_conditions = [ ]
dependent_conditions << " #{ reflection . primary_key_name } = \# {record.quoted_id} "
dependent_conditions << " #{ reflection . options [ :as ] } _type = ' #{ base_class . name } ' " if reflection . options [ :as ]
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dependent_conditions << sanitize_sql ( reflection . options [ :conditions ] , reflection . quoted_table_name ) if reflection . options [ :conditions ]
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dependent_conditions << extra_conditions if extra_conditions
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dependent_conditions = dependent_conditions . collect { | where | " ( #{ where } ) " } . join ( " AND " )
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dependent_conditions = dependent_conditions . gsub ( '@' , '\@' )
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case reflection . options [ :dependent ]
when :destroy
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method_name = " has_many_dependent_destroy_for_ #{ reflection . name } " . to_sym
define_method ( method_name ) do
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send ( reflection . name ) . each { | o | o . destroy }
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end
before_destroy method_name
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when :delete_all
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module_eval %Q{
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before_destroy do | record | # before_destroy do |record|
delete_all_has_many_dependencies ( record , # delete_all_has_many_dependencies(record,
" #{ reflection . name } " , # "posts",
#{reflection.class_name}, # Post,
%@#{dependent_conditions}@ ) # %@...@) # this is a string literal like %(...)
end # end
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}
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when :nullify
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module_eval %Q{
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before_destroy do | record | # before_destroy do |record|
nullify_has_many_dependencies ( record , # nullify_has_many_dependencies(record,
" #{ reflection . name } " , # "posts",
#{reflection.class_name}, # Post,
" #{ reflection . primary_key_name } " , # "user_id",
%@#{dependent_conditions}@ ) # %@...@) # this is a string literal like %(...)
end # end
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}
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else
raise ArgumentError , " The :dependent option expects either :destroy, :delete_all, or :nullify ( #{ reflection . options [ :dependent ] . inspect } ) "
end
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end
end
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# Creates before_destroy callback methods that nullify, delete or destroy
# has_one associated objects, according to the defined :dependent rule.
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def configure_dependency_for_has_one ( reflection )
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if reflection . options . include? ( :dependent )
case reflection . options [ :dependent ]
when :destroy
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method_name = " has_one_dependent_destroy_for_ #{ reflection . name } " . to_sym
define_method ( method_name ) do
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association = send ( reflection . name )
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association . destroy unless association . nil?
end
before_destroy method_name
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when :delete
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method_name = " has_one_dependent_delete_for_ #{ reflection . name } " . to_sym
define_method ( method_name ) do
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# Retrieve the associated object and delete it. The retrieval
# is necessary because there may be multiple associated objects
# with foreign keys pointing to this object, and we only want
# to delete the correct one, not all of them.
association = send ( reflection . name )
association . delete unless association . nil?
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end
before_destroy method_name
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when :nullify
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method_name = " has_one_dependent_nullify_for_ #{ reflection . name } " . to_sym
define_method ( method_name ) do
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association = send ( reflection . name )
association . update_attribute ( reflection . primary_key_name , nil ) unless association . nil?
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end
before_destroy method_name
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else
raise ArgumentError , " The :dependent option expects either :destroy, :delete or :nullify ( #{ reflection . options [ :dependent ] . inspect } ) "
end
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end
end
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def configure_dependency_for_belongs_to ( reflection )
if reflection . options . include? ( :dependent )
case reflection . options [ :dependent ]
when :destroy
method_name = " belongs_to_dependent_destroy_for_ #{ reflection . name } " . to_sym
define_method ( method_name ) do
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association = send ( reflection . name )
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association . destroy unless association . nil?
end
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after_destroy method_name
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when :delete
method_name = " belongs_to_dependent_delete_for_ #{ reflection . name } " . to_sym
define_method ( method_name ) do
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association = send ( reflection . name )
association . delete unless association . nil?
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end
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after_destroy method_name
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else
raise ArgumentError , " The :dependent option expects either :destroy or :delete ( #{ reflection . options [ :dependent ] . inspect } ) "
end
end
end
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def delete_all_has_many_dependencies ( record , reflection_name , association_class , dependent_conditions )
association_class . delete_all ( dependent_conditions )
end
def nullify_has_many_dependencies ( record , reflection_name , association_class , primary_key_name , dependent_conditions )
association_class . update_all ( " #{ primary_key_name } = NULL " , dependent_conditions )
end
mattr_accessor :valid_keys_for_has_many_association
@@valid_keys_for_has_many_association = [
:class_name , :table_name , :foreign_key , :primary_key ,
:dependent ,
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:select , :conditions , :include , :order , :group , :having , :limit , :offset ,
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:as , :through , :source , :source_type ,
:uniq ,
:finder_sql , :counter_sql ,
:before_add , :after_add , :before_remove , :after_remove ,
:extend , :readonly ,
:validate
]
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def create_has_many_reflection ( association_id , options , & extension )
options . assert_valid_keys ( valid_keys_for_has_many_association )
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options [ :extend ] = create_extension_modules ( association_id , extension , options [ :extend ] )
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create_reflection ( :has_many , association_id , options , self )
end
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mattr_accessor :valid_keys_for_has_one_association
@@valid_keys_for_has_one_association = [
:class_name , :foreign_key , :remote , :select , :conditions , :order ,
:include , :dependent , :counter_cache , :extend , :as , :readonly ,
:validate , :primary_key
]
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def create_has_one_reflection ( association_id , options )
options . assert_valid_keys ( valid_keys_for_has_one_association )
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create_reflection ( :has_one , association_id , options , self )
end
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def create_has_one_through_reflection ( association_id , options )
options . assert_valid_keys (
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:class_name , :foreign_key , :remote , :select , :conditions , :order , :include , :dependent , :counter_cache , :extend , :as , :through , :source , :source_type , :validate
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)
create_reflection ( :has_one , association_id , options , self )
end
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mattr_accessor :valid_keys_for_belongs_to_association
@@valid_keys_for_belongs_to_association = [
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:class_name , :primary_key , :foreign_key , :foreign_type , :remote , :select , :conditions ,
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:include , :dependent , :counter_cache , :extend , :polymorphic , :readonly ,
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:validate , :touch
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]
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def create_belongs_to_reflection ( association_id , options )
options . assert_valid_keys ( valid_keys_for_belongs_to_association )
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reflection = create_reflection ( :belongs_to , association_id , options , self )
if options [ :polymorphic ]
reflection . options [ :foreign_type ] || = reflection . class_name . underscore + " _type "
end
reflection
end
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mattr_accessor :valid_keys_for_has_and_belongs_to_many_association
@@valid_keys_for_has_and_belongs_to_many_association = [
:class_name , :table_name , :join_table , :foreign_key , :association_foreign_key ,
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:select , :conditions , :include , :order , :group , :having , :limit , :offset ,
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:uniq ,
:finder_sql , :counter_sql , :delete_sql , :insert_sql ,
:before_add , :after_add , :before_remove , :after_remove ,
:extend , :readonly ,
:validate
]
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def create_has_and_belongs_to_many_reflection ( association_id , options , & extension )
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options . assert_valid_keys ( valid_keys_for_has_and_belongs_to_many_association )
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options [ :extend ] = create_extension_modules ( association_id , extension , options [ :extend ] )
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reflection = create_reflection ( :has_and_belongs_to_many , association_id , options , self )
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if reflection . association_foreign_key == reflection . primary_key_name
raise HasAndBelongsToManyAssociationForeignKeyNeeded . new ( reflection )
end
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reflection . options [ :join_table ] || = join_table_name ( undecorated_table_name ( self . to_s ) , undecorated_table_name ( reflection . class_name ) )
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reflection
end
def reflect_on_included_associations ( associations )
[ associations ] . flatten . collect { | association | reflect_on_association ( association . to_s . intern ) }
end
def guard_against_unlimitable_reflections ( reflections , options )
if ( options [ :offset ] || options [ :limit ] ) && ! using_limitable_reflections? ( reflections )
raise (
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ConfigurationError ,
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" You can not use offset and limit together with has_many or has_and_belongs_to_many associations "
)
end
end
def select_all_rows ( options , join_dependency )
connection . select_all (
construct_finder_sql_with_included_associations ( options , join_dependency ) ,
" #{ name } Load Including Associations "
)
end
def construct_finder_sql_with_included_associations ( options , join_dependency )
scope = scope ( :find )
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sql = " SELECT #{ column_aliases ( join_dependency ) } FROM #{ ( scope && scope [ :from ] ) || options [ :from ] || quoted_table_name } "
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sql << join_dependency . join_associations . collect { | join | join . association_join } . join
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add_joins! ( sql , options [ :joins ] , scope )
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add_conditions! ( sql , options [ :conditions ] , scope )
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add_limited_ids_condition! ( sql , options , join_dependency ) if ! using_limitable_reflections? ( join_dependency . reflections ) && ( ( scope && scope [ :limit ] ) || options [ :limit ] )
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add_group! ( sql , options [ :group ] , options [ :having ] , scope )
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add_order! ( sql , options [ :order ] , scope )
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add_limit! ( sql , options , scope ) if using_limitable_reflections? ( join_dependency . reflections )
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add_lock! ( sql , options , scope )
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return sanitize_sql ( sql )
end
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def add_limited_ids_condition! ( sql , options , join_dependency )
unless ( id_list = select_limited_ids_list ( options , join_dependency ) ) . empty?
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sql << " #{ condition_word ( sql ) } #{ connection . quote_table_name table_name } . #{ primary_key } IN ( #{ id_list } ) "
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else
throw :invalid_query
end
end
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def select_limited_ids_list ( options , join_dependency )
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pk = columns_hash [ primary_key ]
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connection . select_all (
construct_finder_sql_for_association_limiting ( options , join_dependency ) ,
" #{ name } Load IDs For Limited Eager Loading "
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) . collect { | row | connection . quote ( row [ primary_key ] , pk ) } . join ( " , " )
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end
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def construct_finder_sql_for_association_limiting ( options , join_dependency )
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scope = scope ( :find )
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# Only join tables referenced in order or conditions since this is particularly slow on the pre-query.
tables_from_conditions = conditions_tables ( options )
tables_from_order = order_tables ( options )
all_tables = tables_from_conditions + tables_from_order
distinct_join_associations = all_tables . uniq . map { | table |
join_dependency . joins_for_table_name ( table )
} . flatten . compact . uniq
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order = options [ :order ]
if scoped_order = ( scope && scope [ :order ] )
order = order ? " #{ order } , #{ scoped_order } " : scoped_order
end
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is_distinct = ! options [ :joins ] . blank? || include_eager_conditions? ( options , tables_from_conditions ) || include_eager_order? ( options , tables_from_order )
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sql = " SELECT "
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if is_distinct
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sql << connection . distinct ( " #{ connection . quote_table_name table_name } . #{ primary_key } " , order )
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else
sql << primary_key
end
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sql << " FROM #{ connection . quote_table_name table_name } "
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if is_distinct
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sql << distinct_join_associations . collect { | assoc | assoc . association_join } . join
add_joins! ( sql , options [ :joins ] , scope )
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end
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add_conditions! ( sql , options [ :conditions ] , scope )
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add_group! ( sql , options [ :group ] , options [ :having ] , scope )
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if order && is_distinct
connection . add_order_by_for_association_limiting! ( sql , :order = > order )
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else
add_order! ( sql , options [ :order ] , scope )
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end
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add_limit! ( sql , options , scope )
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return sanitize_sql ( sql )
end
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def tables_in_string ( string )
return [ ] if string . blank?
string . scan ( / ([ \ .a-zA-Z_]+).? \ . / ) . flatten
end
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def tables_in_hash ( hash )
return [ ] if hash . blank?
tables = hash . map do | key , value |
if value . is_a? ( Hash )
key . to_s
else
tables_in_string ( key ) if key . is_a? ( String )
end
end
tables . flatten . compact
end
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def conditions_tables ( options )
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# look in both sets of conditions
conditions = [ scope ( :find , :conditions ) , options [ :conditions ] ] . inject ( [ ] ) do | all , cond |
case cond
when nil then all
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when Array then all << tables_in_string ( cond . first )
when Hash then all << tables_in_hash ( cond )
else all << tables_in_string ( cond )
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end
end
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conditions . flatten
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end
def order_tables ( options )
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order = [ options [ :order ] , scope ( :find , :order ) ] . join ( " , " )
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return [ ] unless order && order . is_a? ( String )
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tables_in_string ( order )
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end
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def selects_tables ( options )
select = options [ :select ]
return [ ] unless select && select . is_a? ( String )
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tables_in_string ( select )
end
def joined_tables ( options )
scope = scope ( :find )
joins = options [ :joins ]
merged_joins = scope && scope [ :joins ] && joins ? merge_joins ( scope [ :joins ] , joins ) : ( joins || scope && scope [ :joins ] )
[ table_name ] + case merged_joins
when Symbol , Hash , Array
if array_of_strings? ( merged_joins )
tables_in_string ( merged_joins . join ( ' ' ) )
else
join_dependency = ActiveRecord :: Associations :: ClassMethods :: InnerJoinDependency . new ( self , merged_joins , nil )
join_dependency . join_associations . collect { | join_association | [ join_association . aliased_join_table_name , join_association . aliased_table_name ] } . flatten . compact
end
else
tables_in_string ( merged_joins )
end
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end
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# Checks if the conditions reference a table other than the current model table
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def include_eager_conditions? ( options , tables = nil , joined_tables = nil )
( ( tables || conditions_tables ( options ) ) - ( joined_tables || joined_tables ( options ) ) ) . any?
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end
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# Checks if the query order references a table other than the current model's table.
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def include_eager_order? ( options , tables = nil , joined_tables = nil )
( ( tables || order_tables ( options ) ) - ( joined_tables || joined_tables ( options ) ) ) . any?
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end
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def include_eager_select? ( options , joined_tables = nil )
( selects_tables ( options ) - ( joined_tables || joined_tables ( options ) ) ) . any?
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end
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def references_eager_loaded_tables? ( options )
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joined_tables = joined_tables ( options )
include_eager_order? ( options , nil , joined_tables ) || include_eager_conditions? ( options , nil , joined_tables ) || include_eager_select? ( options , joined_tables )
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end
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def using_limitable_reflections? ( reflections )
reflections . reject { | r | [ :belongs_to , :has_one ] . include? ( r . macro ) } . length . zero?
end
def column_aliases ( join_dependency )
join_dependency . joins . collect { | join | join . column_names_with_alias . collect { | column_name , aliased_name |
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" #{ connection . quote_table_name join . aliased_table_name } . #{ connection . quote_column_name column_name } AS #{ aliased_name } " } } . flatten . join ( " , " )
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end
def add_association_callbacks ( association_name , options )
callbacks = %w( before_add after_add before_remove after_remove )
callbacks . each do | callback_name |
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full_callback_name = " #{ callback_name } _for_ #{ association_name } "
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defined_callbacks = options [ callback_name . to_sym ]
if options . has_key? ( callback_name . to_sym )
class_inheritable_reader full_callback_name . to_sym
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write_inheritable_attribute ( full_callback_name . to_sym , [ defined_callbacks ] . flatten )
else
write_inheritable_attribute ( full_callback_name . to_sym , [ ] )
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end
end
end
def condition_word ( sql )
sql =~ / where /i ? " AND " : " WHERE "
end
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def create_extension_modules ( association_id , block_extension , extensions )
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if block_extension
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extension_module_name = " #{ self . to_s . demodulize } #{ association_id . to_s . camelize } AssociationExtension "
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silence_warnings do
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self . parent . const_set ( extension_module_name , Module . new ( & block_extension ) )
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end
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Array ( extensions ) . push ( " #{ self . parent } :: #{ extension_module_name } " . constantize )
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else
Array ( extensions )
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end
end
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class JoinDependency # :nodoc:
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attr_reader :joins , :reflections , :table_aliases
def initialize ( base , associations , joins )
@joins = [ JoinBase . new ( base , joins ) ]
@associations = associations
@reflections = [ ]
@base_records_hash = { }
@base_records_in_order = [ ]
@table_aliases = Hash . new { | aliases , table | aliases [ table ] = 0 }
@table_aliases [ base . table_name ] = 1
build ( associations )
end
def join_associations
@joins [ 1 .. - 1 ] . to_a
end
def join_base
@joins [ 0 ]
end
def instantiate ( rows )
rows . each_with_index do | row , i |
primary_id = join_base . record_id ( row )
unless @base_records_hash [ primary_id ]
@base_records_in_order << ( @base_records_hash [ primary_id ] = join_base . instantiate ( row ) )
end
construct ( @base_records_hash [ primary_id ] , @associations , join_associations . dup , row )
end
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remove_duplicate_results! ( join_base . active_record , @base_records_in_order , @associations )
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return @base_records_in_order
end
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def remove_duplicate_results! ( base , records , associations )
case associations
when Symbol , String
reflection = base . reflections [ associations ]
if reflection && [ :has_many , :has_and_belongs_to_many ] . include? ( reflection . macro )
records . each { | record | record . send ( reflection . name ) . target . uniq! }
end
when Array
associations . each do | association |
remove_duplicate_results! ( base , records , association )
end
when Hash
associations . keys . each do | name |
reflection = base . reflections [ name ]
is_collection = [ :has_many , :has_and_belongs_to_many ] . include? ( reflection . macro )
parent_records = records . map do | record |
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descendant = record . send ( reflection . name )
next unless descendant
descendant . target . uniq! if is_collection
descendant
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end . flatten . compact
remove_duplicate_results! ( reflection . class_name . constantize , parent_records , associations [ name ] ) unless parent_records . empty?
end
end
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end
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def join_for_table_name ( table_name )
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join = ( @joins . select { | j | j . aliased_table_name == table_name . gsub ( / ^ \ "(.*) \ "$ / ) { $1 } } . first ) rescue nil
return join unless join . nil?
@joins . select { | j | j . is_a? ( JoinAssociation ) && j . aliased_join_table_name == table_name . gsub ( / ^ \ "(.*) \ "$ / ) { $1 } } . first rescue nil
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end
def joins_for_table_name ( table_name )
join = join_for_table_name ( table_name )
result = nil
if join && join . is_a? ( JoinAssociation )
result = [ join ]
if join . parent && join . parent . is_a? ( JoinAssociation )
result = joins_for_table_name ( join . parent . aliased_table_name ) +
result
end
end
result
end
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protected
def build ( associations , parent = nil )
parent || = @joins . last
case associations
when Symbol , String
reflection = parent . reflections [ associations . to_s . intern ] or
raise ConfigurationError , " Association named ' #{ associations } ' was not found; perhaps you misspelled it? "
@reflections << reflection
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@joins << build_join_association ( reflection , parent )
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when Array
associations . each do | association |
build ( association , parent )
end
when Hash
associations . keys . sort { | a , b | a . to_s < = > b . to_s } . each do | name |
build ( name , parent )
build ( associations [ name ] )
end
else
raise ConfigurationError , associations . inspect
end
end
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# overridden in InnerJoinDependency subclass
def build_join_association ( reflection , parent )
JoinAssociation . new ( reflection , self , parent )
end
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def construct ( parent , associations , joins , row )
case associations
when Symbol , String
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join = joins . detect { | j | j . reflection . name . to_s == associations . to_s && j . parent_table_name == parent . class . table_name }
raise ( ConfigurationError , " No such association " ) if join . nil?
joins . delete ( join )
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construct_association ( parent , join , row )
when Array
associations . each do | association |
construct ( parent , association , joins , row )
end
when Hash
associations . keys . sort { | a , b | a . to_s < = > b . to_s } . each do | name |
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join = joins . detect { | j | j . reflection . name . to_s == name . to_s && j . parent_table_name == parent . class . table_name }
raise ( ConfigurationError , " No such association " ) if join . nil?
association = construct_association ( parent , join , row )
joins . delete ( join )
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construct ( association , associations [ name ] , joins , row ) if association
end
else
raise ConfigurationError , associations . inspect
end
end
def construct_association ( record , join , row )
case join . reflection . macro
when :has_many , :has_and_belongs_to_many
collection = record . send ( join . reflection . name )
collection . loaded
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return nil if record . id . to_s != join . parent . record_id ( row ) . to_s or row [ join . aliased_primary_key ] . nil?
association = join . instantiate ( row )
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collection . target . push ( association )
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when :has_one
return if record . id . to_s != join . parent . record_id ( row ) . to_s
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return if record . instance_variable_defined? ( " @ #{ join . reflection . name } " )
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association = join . instantiate ( row ) unless row [ join . aliased_primary_key ] . nil?
record . send ( " set_ #{ join . reflection . name } _target " , association )
when :belongs_to
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return if record . id . to_s != join . parent . record_id ( row ) . to_s or row [ join . aliased_primary_key ] . nil?
association = join . instantiate ( row )
record . send ( " set_ #{ join . reflection . name } _target " , association )
else
raise ConfigurationError , " unknown macro: #{ join . reflection . macro } "
end
return association
end
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class JoinBase # :nodoc:
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attr_reader :active_record , :table_joins
delegate :table_name , :column_names , :primary_key , :reflections , :sanitize_sql , :to = > :active_record
def initialize ( active_record , joins = nil )
@active_record = active_record
@cached_record = { }
@table_joins = joins
end
def aliased_prefix
" t0 "
end
def aliased_primary_key
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" #{ aliased_prefix } _r0 "
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end
def aliased_table_name
active_record . table_name
end
def column_names_with_alias
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unless defined? ( @column_names_with_alias )
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@column_names_with_alias = [ ]
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( [ primary_key ] + ( column_names - [ primary_key ] ) ) . each_with_index do | column_name , i |
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@column_names_with_alias << [ column_name , " #{ aliased_prefix } _r #{ i } " ]
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end
end
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@column_names_with_alias
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end
def extract_record ( row )
column_names_with_alias . inject ( { } ) { | record , ( cn , an ) | record [ cn ] = row [ an ] ; record }
end
def record_id ( row )
row [ aliased_primary_key ]
end
def instantiate ( row )
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@cached_record [ record_id ( row ) ] || = active_record . send ( :instantiate , extract_record ( row ) )
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end
end
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class JoinAssociation < JoinBase # :nodoc:
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attr_reader :reflection , :parent , :aliased_table_name , :aliased_prefix , :aliased_join_table_name , :parent_table_name
delegate :options , :klass , :through_reflection , :source_reflection , :to = > :reflection
def initialize ( reflection , join_dependency , parent = nil )
reflection . check_validity!
if reflection . options [ :polymorphic ]
raise EagerLoadPolymorphicError . new ( reflection )
end
super ( reflection . klass )
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@join_dependency = join_dependency
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@parent = parent
@reflection = reflection
@aliased_prefix = " t #{ join_dependency . joins . size } "
@parent_table_name = parent . active_record . table_name
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@aliased_table_name = aliased_table_name_for ( table_name )
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if reflection . macro == :has_and_belongs_to_many
@aliased_join_table_name = aliased_table_name_for ( reflection . options [ :join_table ] , " _join " )
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end
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if [ :has_many , :has_one ] . include? ( reflection . macro ) && reflection . options [ :through ]
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@aliased_join_table_name = aliased_table_name_for ( reflection . through_reflection . klass . table_name , " _join " )
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end
end
def association_join
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connection = reflection . active_record . connection
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join = case reflection . macro
when :has_and_belongs_to_many
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" #{ join_type } %s ON %s.%s = %s.%s " % [
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table_alias_for ( options [ :join_table ] , aliased_join_table_name ) ,
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connection . quote_table_name ( aliased_join_table_name ) ,
options [ :foreign_key ] || reflection . active_record . to_s . foreign_key ,
connection . quote_table_name ( parent . aliased_table_name ) ,
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reflection . active_record . primary_key ] +
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" #{ join_type } %s ON %s.%s = %s.%s " % [
table_name_and_alias ,
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connection . quote_table_name ( aliased_table_name ) ,
klass . primary_key ,
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connection . quote_table_name ( aliased_join_table_name ) ,
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options [ :association_foreign_key ] || klass . to_s . foreign_key
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]
when :has_many , :has_one
case
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when reflection . options [ :through ]
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through_conditions = through_reflection . options [ :conditions ] ? " AND #{ interpolate_sql ( sanitize_sql ( through_reflection . options [ :conditions ] ) ) } " : ''
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jt_foreign_key = jt_as_extra = jt_source_extra = jt_sti_extra = nil
first_key = second_key = as_extra = nil
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if through_reflection . options [ :as ] # has_many :through against a polymorphic join
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jt_foreign_key = through_reflection . options [ :as ] . to_s + '_id'
jt_as_extra = " AND %s.%s = %s " % [
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connection . quote_table_name ( aliased_join_table_name ) ,
connection . quote_column_name ( through_reflection . options [ :as ] . to_s + '_type' ) ,
klass . quote_value ( parent . active_record . base_class . name )
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]
else
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jt_foreign_key = through_reflection . primary_key_name
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end
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case source_reflection . macro
when :has_many
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if source_reflection . options [ :as ]
first_key = " #{ source_reflection . options [ :as ] } _id "
second_key = options [ :foreign_key ] || primary_key
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as_extra = " AND %s.%s = %s " % [
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connection . quote_table_name ( aliased_table_name ) ,
connection . quote_column_name ( " #{ source_reflection . options [ :as ] } _type " ) ,
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klass . quote_value ( source_reflection . active_record . base_class . name )
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]
else
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first_key = through_reflection . klass . base_class . to_s . foreign_key
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second_key = options [ :foreign_key ] || primary_key
end
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unless through_reflection . klass . descends_from_active_record?
jt_sti_extra = " AND %s.%s = %s " % [
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connection . quote_table_name ( aliased_join_table_name ) ,
connection . quote_column_name ( through_reflection . active_record . inheritance_column ) ,
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through_reflection . klass . quote_value ( through_reflection . klass . sti_name ) ]
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end
when :belongs_to
first_key = primary_key
if reflection . options [ :source_type ]
second_key = source_reflection . association_foreign_key
jt_source_extra = " AND %s.%s = %s " % [
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connection . quote_table_name ( aliased_join_table_name ) ,
connection . quote_column_name ( reflection . source_reflection . options [ :foreign_type ] ) ,
klass . quote_value ( reflection . options [ :source_type ] )
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]
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else
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second_key = source_reflection . primary_key_name
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end
end
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" #{ join_type } %s ON (%s.%s = %s.%s%s%s%s) " % [
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table_alias_for ( through_reflection . klass . table_name , aliased_join_table_name ) ,
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connection . quote_table_name ( parent . aliased_table_name ) ,
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connection . quote_column_name ( parent . primary_key ) ,
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connection . quote_table_name ( aliased_join_table_name ) ,
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connection . quote_column_name ( jt_foreign_key ) ,
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jt_as_extra , jt_source_extra , jt_sti_extra
] +
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" #{ join_type } %s ON (%s.%s = %s.%s%s) " % [
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table_name_and_alias ,
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connection . quote_table_name ( aliased_table_name ) ,
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connection . quote_column_name ( first_key ) ,
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connection . quote_table_name ( aliased_join_table_name ) ,
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connection . quote_column_name ( second_key ) ,
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as_extra
]
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when reflection . options [ :as ] && [ :has_many , :has_one ] . include? ( reflection . macro )
" #{ join_type } %s ON %s.%s = %s.%s AND %s.%s = %s " % [
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table_name_and_alias ,
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connection . quote_table_name ( aliased_table_name ) ,
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" #{ reflection . options [ :as ] } _id " ,
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connection . quote_table_name ( parent . aliased_table_name ) ,
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parent . primary_key ,
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connection . quote_table_name ( aliased_table_name ) ,
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" #{ reflection . options [ :as ] } _type " ,
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klass . quote_value ( parent . active_record . base_class . name )
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]
else
foreign_key = options [ :foreign_key ] || reflection . active_record . name . foreign_key
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" #{ join_type } %s ON %s.%s = %s.%s " % [
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table_name_and_alias ,
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aliased_table_name ,
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foreign_key ,
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parent . aliased_table_name ,
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reflection . options [ :primary_key ] || parent . primary_key
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]
end
when :belongs_to
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" #{ join_type } %s ON %s.%s = %s.%s " % [
table_name_and_alias ,
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connection . quote_table_name ( aliased_table_name ) ,
reflection . klass . primary_key ,
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connection . quote_table_name ( parent . aliased_table_name ) ,
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options [ :foreign_key ] || reflection . primary_key_name
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]
else
" "
end || ''
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join << %( AND %s ) % [
klass . send ( :type_condition , aliased_table_name ) ] unless klass . descends_from_active_record?
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[ through_reflection , reflection ] . each do | ref |
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join << " AND #{ interpolate_sql ( sanitize_sql ( ref . options [ :conditions ] , aliased_table_name ) ) } " if ref && ref . options [ :conditions ]
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end
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join
end
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protected
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def aliased_table_name_for ( name , suffix = nil )
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if ! parent . table_joins . blank? && parent . table_joins . to_s . downcase =~ %r{ join( \ s+ \ w+)? \ s+ #{ active_record . connection . quote_table_name name . downcase } \ son }
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@join_dependency . table_aliases [ name ] += 1
end
unless @join_dependency . table_aliases [ name ] . zero?
# if the table name has been used, then use an alias
name = active_record . connection . table_alias_for " #{ pluralize ( reflection . name ) } _ #{ parent_table_name } #{ suffix } "
table_index = @join_dependency . table_aliases [ name ]
@join_dependency . table_aliases [ name ] += 1
name = name [ 0 .. active_record . connection . table_alias_length - 3 ] + " _ #{ table_index + 1 } " if table_index > 0
else
@join_dependency . table_aliases [ name ] += 1
end
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name
end
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def pluralize ( table_name )
ActiveRecord :: Base . pluralize_table_names ? table_name . to_s . pluralize : table_name
end
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def table_alias_for ( table_name , table_alias )
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" #{ reflection . active_record . connection . quote_table_name ( table_name ) } #{ table_alias if table_name != table_alias } " . strip
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end
def table_name_and_alias
table_alias_for table_name , @aliased_table_name
end
def interpolate_sql ( sql )
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instance_eval ( " %@ #{ sql . gsub ( '@' , '\@' ) } @ " )
end
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private
def join_type
" LEFT OUTER JOIN "
end
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end
end
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class InnerJoinDependency < JoinDependency # :nodoc:
protected
def build_join_association ( reflection , parent )
InnerJoinAssociation . new ( reflection , self , parent )
end
class InnerJoinAssociation < JoinAssociation
private
def join_type
" INNER JOIN "
end
end
end
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end
end
end