97 lines
3.9 KiB
Ruby
97 lines
3.9 KiB
Ruby
module ActiveRecord
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module Acts #:nodoc:
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module Tree #:nodoc:
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def self.included(base)
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base.extend(ClassMethods)
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end
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# Specify this act if you want to model a tree structure by providing a parent association and a children
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# association. This act requires that you have a foreign key column, which by default is called parent_id.
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#
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# class Category < ActiveRecord::Base
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# acts_as_tree :order => "name"
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# end
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#
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# Example:
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# root
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# \_ child1
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# \_ subchild1
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# \_ subchild2
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#
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# root = Category.create("name" => "root")
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# child1 = root.children.create("name" => "child1")
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# subchild1 = child1.children.create("name" => "subchild1")
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#
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# root.parent # => nil
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# child1.parent # => root
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# root.children # => [child1]
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# root.children.first.children.first # => subchild1
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#
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# In addition to the parent and children associations, the following instance methods are added to the class
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# after specifying the act:
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# * siblings : Returns all the children of the parent, excluding the current node ([ subchild2 ] when called from subchild1)
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# * self_and_siblings : Returns all the children of the parent, including the current node ([ subchild1, subchild2 ] when called from subchild1)
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# * ancestors : Returns all the ancestors of the current node ([child1, root] when called from subchild2)
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# * root : Returns the root of the current node (root when called from subchild2)
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module ClassMethods
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# Configuration options are:
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#
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# * <tt>foreign_key</tt> - specifies the column name to use for tracking of the tree (default: parent_id)
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# * <tt>order</tt> - makes it possible to sort the children according to this SQL snippet.
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# * <tt>counter_cache</tt> - keeps a count in a children_count column if set to true (default: false).
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def acts_as_tree(options = {})
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configuration = { :foreign_key => "parent_id", :order => nil, :counter_cache => nil }
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configuration.update(options) if options.is_a?(Hash)
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belongs_to :parent, :class_name => name, :foreign_key => configuration[:foreign_key], :counter_cache => configuration[:counter_cache]
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has_many :children, :class_name => name, :foreign_key => configuration[:foreign_key], :order => configuration[:order], :dependent => :destroy
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class_eval <<-EOV
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include ActiveRecord::Acts::Tree::InstanceMethods
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def self.roots
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find(:all, :conditions => "#{configuration[:foreign_key]} IS NULL", :order => #{configuration[:order].nil? ? "nil" : %Q{"#{configuration[:order]}"}})
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end
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def self.root
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find(:first, :conditions => "#{configuration[:foreign_key]} IS NULL", :order => #{configuration[:order].nil? ? "nil" : %Q{"#{configuration[:order]}"}})
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end
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EOV
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end
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end
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module InstanceMethods
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# Returns list of ancestors, starting from parent until root.
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#
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# subchild1.ancestors # => [child1, root]
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def ancestors
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node, nodes = self, []
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nodes << node = node.parent while node.parent
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nodes
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end
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# Returns the root node of the tree.
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def root
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node = self
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node = node.parent while node.parent
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node
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end
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# Returns all siblings of the current node.
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#
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# subchild1.siblings # => [subchild2]
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def siblings
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self_and_siblings - [self]
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end
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# Returns all siblings and a reference to the current node.
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#
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# subchild1.self_and_siblings # => [subchild1, subchild2]
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def self_and_siblings
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parent ? parent.children : self.class.roots
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end
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end
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end
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end
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end
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