require 'rubygems' require 'extlib' require 'digest/md5' require File.dirname(__FILE__) + '/document' # = CouchRest::Model - ORM, the CouchDB way module CouchRest # = CouchRest::Model - ORM, the CouchDB way # # CouchRest::Model provides an ORM-like interface for CouchDB documents. It # avoids all usage of method_missing, and tries to strike a balance # between usability and magic. See CouchRest::Model#view_by for # documentation about the view-generation system. # # ==== Example # # This is an example class using CouchRest::Model. It is taken from the # spec/couchrest/core/model_spec.rb file, which may be even more up to date # than this example. # # class Article < CouchRest::Model # use_database CouchRest.database!('http://127.0.0.1:5984/couchrest-model-test') # unique_id :slug # # view_by :date, :descending => true # view_by :user_id, :date # # view_by :tags, # :map => # "function(doc) { # if (doc['couchrest-type'] == 'Article' && doc.tags) { # doc.tags.forEach(function(tag){ # emit(tag, 1); # }); # } # }", # :reduce => # "function(keys, values, rereduce) { # return sum(values); # }" # # key_writer :date # key_reader :slug, :created_at, :updated_at # key_accessor :title, :tags # # timestamps! # # before(:create, :generate_slug_from_title) # def generate_slug_from_title # self['slug'] = title.downcase.gsub(/[^a-z0-9]/,'-').squeeze('-').gsub(/^\-|\-$/,'') # end # end # # ==== Examples of finding articles with these views: # # * All the articles by Barney published in the last 24 hours. Note that we # use {} as a special value that sorts after all strings, # numbers, and arrays. # # Article.by_user_id_and_date :startkey => ["barney", Time.now - 24 * 3600], :endkey => ["barney", {}] # # * The most recent 20 articles. Remember that the view_by :date # has the default option :descending => true. # # Article.by_date :count => 20 # # * The raw CouchDB view reduce result for the custom :tags view. # In this case we'll get a count of the number of articles tagged "ruby". # # Article.by_tags :key => "ruby", :reduce => true # class Model < Document # instantiates the hash by converting all the keys to strings. def initialize keys = {} super(keys) apply_defaults cast_keys unless self['_id'] && self['_rev'] self['couchrest-type'] = self.class.to_s end end # this is the CouchRest::Database that model classes will use unless # they override it with use_database cattr_accessor :default_database class_inheritable_accessor :casts class_inheritable_accessor :default_obj class_inheritable_accessor :class_database class_inheritable_accessor :design_doc class_inheritable_accessor :design_doc_slug_cache class_inheritable_accessor :design_doc_fresh class << self # override the CouchRest::Model-wide default_database def use_database db self.class_database = db end # returns the CouchRest::Database instance that this class uses def database self.class_database || CouchRest::Model.default_database end # Load a document from the database by id def get id doc = database.get id new(doc) end # Load all documents that have the "couchrest-type" field equal to the # name of the current class. Take the standard set of # CouchRest::Database#view options. def all opts = {}, &block self.design_doc ||= Design.new(default_design_doc) unless design_doc_fresh refresh_design_doc end view :all, opts, &block end # Load the first document that have the "couchrest-type" field equal to # the name of the current class. # # ==== Returns # Object:: The first object instance available # or # Nil:: if no instances available # # ==== Parameters # opts:: # View options, see CouchRest::Database#view options for more info. def first opts = {} first_instance = self.all(opts.merge!(:count => 1)) first_instance.empty? ? nil : first_instance.first end # Cast a field as another class. The class must be happy to have the # field's primitive type as the argument to it's constuctur. Classes # which inherit from CouchRest::Model are happy to act as sub-objects # for any fields that are stored in JSON as object (and therefore are # parsed from the JSON as Ruby Hashes). # # Example: # # class Post < CouchRest::Model # # key_accessor :title, :body, :author # # cast :author, :as => 'Author' # # end # # post.author.class #=> Author # # Using the same example, if a Post should have many Comments, we # would declare it like this: # # class Post < CouchRest::Model # # key_accessor :title, :body, :author, comments # # cast :author, :as => 'Author' # cast :comments, :as => ['Comment'] # # end # # post.author.class #=> Author # post.comments.class #=> Array # post.comments.first #=> Comment # def cast field, opts = {} self.casts ||= {} self.casts[field.to_s] = opts end # Defines methods for reading and writing from fields in the document. # Uses key_writer and key_reader internally. def key_accessor *keys key_writer *keys key_reader *keys end # For each argument key, define a method key= that sets the # corresponding field on the CouchDB document. def key_writer *keys keys.each do |method| key = method.to_s define_method "#{method}=" do |value| self[key] = value end end end # For each argument key, define a method key that reads the # corresponding field on the CouchDB document. def key_reader *keys keys.each do |method| key = method.to_s define_method method do self[key] end end end def default self.default_obj end def set_default hash self.default_obj = hash end # Automatically set updated_at and created_at fields # on the document whenever saving occurs. CouchRest uses a pretty # decent time format by default. See Time#to_json def timestamps! before(:create) do self['updated_at'] = self['created_at'] = Time.now end before(:update) do self['updated_at'] = Time.now end end # Name a method that will be called before the document is first saved, # which returns a string to be used for the document's _id. # Because CouchDB enforces a constraint that each id must be unique, # this can be used to enforce eg: uniq usernames. Note that this id # must be globally unique across all document types which share a # database, so if you'd like to scope uniqueness to this class, you # should use the class name as part of the unique id. def unique_id method = nil, &block if method define_method :set_unique_id do self['_id'] ||= self.send(method) end elsif block define_method :set_unique_id do uniqid = block.call(self) raise ArgumentError, "unique_id block must not return nil" if uniqid.nil? self['_id'] ||= uniqid end end end # Define a CouchDB view. The name of the view will be the concatenation # of by and the keys joined by _and_ # # ==== Example views: # # class Post # # view with default options # # query with Post.by_date # view_by :date, :descending => true # # # view with compound sort-keys # # query with Post.by_user_id_and_date # view_by :user_id, :date # # # view with custom map/reduce functions # # query with Post.by_tags :reduce => true # view_by :tags, # :map => # "function(doc) { # if (doc['couchrest-type'] == 'Post' && doc.tags) { # doc.tags.forEach(function(tag){ # emit(doc.tag, 1); # }); # } # }", # :reduce => # "function(keys, values, rereduce) { # return sum(values); # }" # end # # view_by :date will create a view defined by this Javascript # function: # # function(doc) { # if (doc['couchrest-type'] == 'Post' && doc.date) { # emit(doc.date, null); # } # } # # It can be queried by calling Post.by_date which accepts all # valid options for CouchRest::Database#view. In addition, calling with # the :raw => true option will return the view rows # themselves. By default Post.by_date will return the # documents included in the generated view. # # CouchRest::Database#view options can be applied at view definition # time as defaults, and they will be curried and used at view query # time. Or they can be overridden at query time. # # Custom views can be queried with :reduce => true to return # reduce results. The default for custom views is to query with # :reduce => false. # # Views are generated (on a per-model basis) lazily on first-access. # This means that if you are deploying changes to a view, the views for # that model won't be available until generation is complete. This can # take some time with large databases. Strategies are in the works. # # To understand the capabilities of this view system more compeletly, # it is recommended that you read the RSpec file at # spec/core/model_spec.rb. def view_by *keys self.design_doc ||= Design.new(default_design_doc) opts = keys.pop if keys.last.is_a?(Hash) opts ||= {} ducktype = opts.delete(:ducktype) unless ducktype || opts[:map] opts[:guards] ||= [] opts[:guards].push "(doc['couchrest-type'] == '#{self.to_s}')" end keys.push opts self.design_doc.view_by(*keys) self.design_doc_fresh = false end def method_missing m, *args if has_view?(m) query = args.shift || {} view(m, query, *args) else super end end # returns stored defaults if the there is a view named this in the design doc def has_view?(view) view = view.to_s design_doc && design_doc['views'] && design_doc['views'][view] end # Dispatches to any named view. def view name, query={}, &block unless design_doc_fresh refresh_design_doc end query[:raw] = true if query[:reduce] raw = query.delete(:raw) fetch_view_with_docs(name, query, raw, &block) end def all_design_doc_versions database.documents :startkey => "_design/#{self.to_s}-", :endkey => "_design/#{self.to_s}-\u9999" end # Deletes any non-current design docs that were created by this class. # Running this when you're deployed version of your application is steadily # and consistently using the latest code, is the way to clear out old design # docs. Running it to early could mean that live code has to regenerate # potentially large indexes. def cleanup_design_docs! ddocs = all_design_doc_versions ddocs["rows"].each do |row| if (row['id'] != design_doc_id) database.delete({ "_id" => row['id'], "_rev" => row['value']['rev'] }) end end end private def fetch_view_with_docs name, opts, raw=false, &block if raw fetch_view name, opts, &block else begin view = fetch_view name, opts.merge({:include_docs => true}), &block view['rows'].collect{|r|new(r['doc'])} if view['rows'] rescue # fallback for old versions of couchdb that don't # have include_docs support view = fetch_view name, opts, &block view['rows'].collect{|r|new(database.get(r['id']))} if view['rows'] end end end def fetch_view view_name, opts, &block retryable = true begin design_doc.view(view_name, opts, &block) # the design doc could have been deleted by a rouge process rescue RestClient::ResourceNotFound => e if retryable refresh_design_doc retryable = false retry else raise e end end end def design_doc_id "_design/#{design_doc_slug}" end def design_doc_slug return design_doc_slug_cache if design_doc_slug_cache && design_doc_fresh funcs = [] design_doc['views'].each do |name, view| funcs << "#{name}/#{view['map']}#{view['reduce']}" end md5 = Digest::MD5.hexdigest(funcs.sort.join('')) self.design_doc_slug_cache = "#{self.to_s}-#{md5}" end def default_design_doc { "language" => "javascript", "views" => { 'all' => { 'map' => "function(doc) { if (doc['couchrest-type'] == '#{self.to_s}') { emit(null,null); } }" } } } end def refresh_design_doc did = design_doc_id saved = database.get(did) rescue nil if saved design_doc['views'].each do |name, view| saved['views'][name] = view end database.save(saved) else design_doc['_id'] = did design_doc.delete('_rev') design_doc.database = database design_doc.save end self.design_doc_fresh = true end end # class << self # returns the database used by this model's class def database self.class.database end # Takes a hash as argument, and applies the values by using writer methods # for each key. It doesn't save the document at the end. Raises a NoMethodError if the corresponding methods are # missing. In case of error, no attributes are changed. def update_attributes_without_saving hash hash.each do |k, v| raise NoMethodError, "#{k}= method not available, use key_accessor or key_writer :#{k}" unless self.respond_to?("#{k}=") end hash.each do |k, v| self.send("#{k}=",v) end end # Takes a hash as argument, and applies the values by using writer methods # for each key. Raises a NoMethodError if the corresponding methods are # missing. In case of error, no attributes are changed. def update_attributes hash update_attributes_without_saving hash save end # for compatibility with old-school frameworks alias :new_record? :new_document? # We override this to create the create and update callback opportunities. # I think we should drop those and just have save. If you care, in your callback, # check new_document? def save actually=false if actually super() else if new_document? create else update end end end # Saves the document to the db using create or update. Raises an exception # if the document is not saved properly. def save! raise "#{self.inspect} failed to save" unless self.save end def update save :actually end # Deletes the document from the database. Runs the :delete callbacks. # Removes the _id and _rev fields, preparing the # document to be saved to a new _id. def destroy result = database.delete self if result['ok'] self['_rev'] = nil self['_id'] = nil end result['ok'] end def create # can we use the callbacks for this? set_unique_id if self.respond_to?(:set_unique_id) save :actually end private def apply_defaults if self.class.default self.class.default.each do |k,v| self[k] = v end end end def cast_keys return unless self.class.casts # TODO move the argument checking to the cast method for early crashes self.class.casts.each do |k,v| next unless self[k] target = v[:as] if target.is_a?(Array) klass = ::Extlib::Inflection.constantize(target[0]) self[k] = self[k].collect do |value| klass.new(value) end else self[k] = ::Extlib::Inflection.constantize(target).new(self[k]) end end end include ::Extlib::Hook # todo: drop create and update hooks... # (use new_record? in callbacks if you care) register_instance_hooks :save, :create, :update, :destroy end # class Model end # module CouchRest