require 'active_record/associations/association_collection' require 'active_record/associations/has_many_association' require 'active_record/associations/has_and_belongs_to_many_association' require 'active_record/deprecated_associations' module ActiveRecord module Associations # :nodoc: def self.append_features(base) super base.extend(ClassMethods) end # Clears out the association cache def clear_association_cache #:nodoc: self.class.reflect_on_all_associations.to_a.each do |assoc| instance_variable_set "@#{assoc.name}", nil end end # 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 was as Ruby's own attr* # methods. Example: # # class Project < ActiveRecord::Base # belongs_to :portfolio # has_one :project_manager # 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: # * Project#portfolio, Project#portfolio=(portfolio), Project#portfolio.nil?, Project#portfolio?(portfolio) # * Project#project_manager, Project#project_manager=(project_manager), Project#project_manager.nil?, # Project#project_manager?(project_manager), Project#build_project_manager, Project#create_project_manager # * Project#milestones.empty?, Project#milestones.size, Project#milestones, Project#milestones<<(milestone), # Project#milestones.delete(milestone), Project#milestones.find(milestone_id), Project#milestones.find_all(conditions), # Project#milestones.build, Project#milestones.create # * Project#categories.empty?, Project#categories.size, Project#categories, Project#categories<<(category1), # Project#categories.delete(category1) # # == Example # # link:../examples/associations.png # # == Is it belongs_to or has_one? # # Both express a 1-1 relationship, the difference is mostly where to place the foreign key, which goes on the table for the class # saying belongs_to. Example: # # class Post < ActiveRecord::Base # has_one :author # end # # class Author < ActiveRecord::Base # belongs_to :post # end # # The tables for these classes could look something like: # # CREATE TABLE posts ( # id int(11) NOT NULL auto_increment, # title varchar default NULL, # PRIMARY KEY (id) # ) # # CREATE TABLE authors ( # id int(11) NOT NULL auto_increment, # post_id int(11) default NULL, # name varchar default NULL, # PRIMARY KEY (id) # ) # # == Caching # # All of the methods are built on a simple caching principle that will keep the result of the last query around unless specifically # instructed not to. The cache is even shared across methods to make it even cheaper to use the macro-added methods without # 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 # # == 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 # # class Company < ActiveRecord::Base; end # end # end # # When Firm#clients is called, it'll in turn call MyApplication::Business::Company.find(firm.id). If you want to associate # with a class in another module scope this can be done by specifying the complete class name, such as: # # 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 # # == Type safety with ActiveRecord::AssociationTypeMismatch # # If you attempt to assign an object to an association that doesn't match the inferred or specified :class_name, you'll # get a ActiveRecord::AssociationTypeMismatch. # # == Options # # All of the association macros can be specialized through options which makes more complex cases than the simple and guessable ones # possible. module ClassMethods # Adds the following methods for retrieval and query of collections of associated objects. # +collection+ is replaced with the symbol passed as the first argument, so # has_many :clients would add among others has_clients?. # * collection(force_reload = false) - returns an array of all the associated objects. # An empty array is returned if none are found. # * 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. This does not destroy the objects. # * 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 # meets the condition that it has to be associated with this object. # * collection.find_all(conditions = nil, orderings = nil, limit = nil, joins = nil) - finds all associated objects responding # criterias mentioned (like in the standard find_all) and that meets the condition that it has to be associated with this object. # * collection.build(attributes = {}) - returns a new object of the collection type that has been instantiated # with +attributes+ and linked to this object through a foreign key but has not yet been saved. # * collection.create(attributes = {}) - returns a new object of the collection type that has been instantiated # with +attributes+ and linked to this object through a foreign key and that has already been saved (if it passed the validation). # # Example: A Firm class declares has_many :clients, which will add: # * Firm#clients (similar to Clients.find_all "firm_id = #{id}") # * Firm#clients<< # * Firm#clients.delete # * Firm#clients.clear # * Firm#clients.empty? (similar to firm.clients.size == 0) # * Firm#clients.size (similar to Client.count "firm_id = #{id}") # * Firm#clients.find (similar to Client.find_on_conditions(id, "firm_id = #{id}")) # * Firm#clients.find_all (similar to Client.find_all "firm_id = #{id}") # * Firm#clients.build (similar to Client.new("firm_id" => id)) # * Firm#clients.create (similar to c = Client.new("client_id" => id); c.save; c) # The declaration can also include an options hash to specialize the behavior of the association. # # Options are: # * :class_name - specify the class name of the association. Use it only if that name can't be infered # from the association name. So has_many :products 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. # * :conditions - specify the conditions that the associated objects must meet in order to be included as a "WHERE" # sql fragment, such as "price > 5 AND name LIKE 'B%'". # * :order - specify the order in which the associated objects are returned as a "ORDER BY" sql fragment, # such as "last_name, first_name DESC" # * :foreign_key - specify the foreign key used for the association. By default this is guessed to be the name # 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 foreign_key. # * :dependent - if set to true all the associated object are destroyed alongside this object. # May not be set if :exclusively_dependent is also set. # * :exclusively_dependent - if set to true all the associated object are deleted in one SQL statement without having their # before_destroy callback run. This should only be used on associations that depend solely on this class and don't need to do any # clean-up in before_destroy. The upside is that it's much faster, especially if there's a counter_cache involved. # May not be set if :dependent is also set. # * :finder_sql - specify a complete SQL statement to fetch the association. This is a good way to go for complex # associations that depends on multiple tables. Note: When this option is used, +find_in_collection+ is _not_ added. # * :counter_sql - specify a complete SQL statement to fetch the size of the association. If +:finder_sql+ is # specified but +:counter_sql+, +:counter_sql+ will be generated by replacing SELECT ... FROM with SELECT COUNT(*) FROM. # # Option examples: # has_many :comments, :order => "posted_on" # has_many :people, :class_name => "Person", :conditions => "deleted = 0", :order => "name" # has_many :tracks, :order => "position", :dependent => true # 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 = {}) validate_options([ :foreign_key, :class_name, :exclusively_dependent, :dependent, :conditions, :order, :finder_sql, :counter_sql ], options.keys) association_name, association_class_name, association_class_primary_key_name = associate_identification(association_id, options[:class_name], options[:foreign_key]) require_association_class(association_class_name) if options[:dependent] and options[:exclusively_dependent] raise ArgumentError, ':dependent and :exclusively_dependent are mutually exclusive options. You may specify one or the other.' # ' ruby-mode elsif options[:dependent] module_eval "before_destroy '#{association_name}.each { |o| o.destroy }'" elsif options[:exclusively_dependent] module_eval "before_destroy { |record| #{association_class_name}.delete_all(%(#{association_class_primary_key_name} = \#{record.quoted_id})) }" end define_method(association_name) do |*params| force_reload = params.first unless params.empty? association = instance_variable_get("@#{association_name}") if association.nil? association = HasManyAssociation.new(self, association_name, association_class_name, association_class_primary_key_name, options) instance_variable_set("@#{association_name}", association) end association.reload if force_reload association end # deprecated api deprecated_collection_count_method(association_name) deprecated_add_association_relation(association_name) deprecated_remove_association_relation(association_name) deprecated_has_collection_method(association_name) deprecated_find_in_collection_method(association_name) deprecated_find_all_in_collection_method(association_name) deprecated_create_method(association_name) deprecated_build_method(association_name) end # Adds the following methods for retrieval and query of a single associated object. # +association+ is replaced with the symbol passed as the first argument, so # has_one :manager would add among others has_manager?. # * 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, # and saves the associate object. # * association?(object, force_reload = false) - returns true if the +object+ is of the same type and has the # same id as the associated object. # * association.nil? - returns true if there is no associated object. # * 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. # * create_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 and that has already been saved (if it passed the validation). # # Example: An Account class declares has_one :beneficiary, which will add: # * Account#beneficiary (similar to Beneficiary.find_first "account_id = #{id}") # * Account#beneficiary=(beneficiary) (similar to beneficiary.account_id = account.id; beneficiary.save) # * Account#beneficiary? (similar to account.beneficiary == some_beneficiary) # * Account#beneficiary.nil? # * Account#build_beneficiary (similar to Beneficiary.new("account_id" => id)) # * Account#create_beneficiary (similar to b = Beneficiary.new("account_id" => id); b.save; b) # The declaration can also include an options hash to specialize the behavior of the association. # # Options are: # * :class_name - specify the class name of the association. Use it only if that name can't be infered # from the association name. So has_one :manager 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. # * :conditions - specify the conditions that the associated object must meet in order to be included as a "WHERE" # sql fragment, such as "rank = 5". # * :order - specify the order from which the associated object will be picked at the top. Specified as # an "ORDER BY" sql fragment, such as "last_name, first_name DESC" # * :dependent - if set to true the associated object is destroyed alongside this object # * :foreign_key - specify the foreign key used for the association. By default this is guessed to be the name # 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 foreign_key. # # Option examples: # has_one :credit_card, :dependent => true # has_one :last_comment, :class_name => "Comment", :order => "posted_on" # has_one :project_manager, :class_name => "Person", :conditions => "role = 'project_manager'" def has_one(association_id, options = {}) options.merge!({ :remote => true }) belongs_to(association_id, options) association_name, association_class_name, class_primary_key_name = associate_identification(association_id, options[:class_name], options[:foreign_key], false) require_association_class(association_class_name) has_one_writer_method(association_name, association_class_name, class_primary_key_name) build_method("build_", association_name, association_class_name, class_primary_key_name) create_method("create_", association_name, association_class_name, class_primary_key_name) module_eval "before_destroy '#{association_name}.destroy if has_#{association_name}?'" if options[:dependent] end # Adds the following methods for retrieval and query for a single associated object that this object holds an id to. # +association+ is replaced with the symbol passed as the first argument, so # belongs_to :author would add among others has_author?. # * 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. # * association?(object, force_reload = false) - returns true if the +object+ is of the same type and has the # same id as the associated object. # * association.nil? - returns true if there is no associated object. # # Example: A Post class declares has_one :author, which will add: # * Post#author (similar to Author.find(author_id)) # * Post#author=(author) (similar to post.author_id = author.id) # * Post#author? (similar to post.author == some_author) # * Post#author.nil? # The declaration can also include an options hash to specialize the behavior of the association. # # Options are: # * :class_name - specify the class name of the association. Use it only if that name can't be infered # from the association name. So has_one :author 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. # * :conditions - specify the conditions that the associated object must meet in order to be included as a "WHERE" # sql fragment, such as "authorized = 1". # * :order - specify the order from which the associated object will be picked at the top. Specified as # an "ORDER BY" sql fragment, such as "last_name, first_name DESC" # * :foreign_key - specify the foreign key used for the association. By default this is guessed to be the name # of the associated class in lower-case and "_id" suffixed. So a +Person+ class that makes a belongs_to association to a # +Boss+ class will use "boss_id" as the default foreign_key. # * :counter_cache - caches the number of belonging objects on the associate class through use of increment_counter # and decrement_counter. The counter cache is incremented when an object of this class is created and decremented when it's # destroyed. This requires that a column named "#{table_name}_count" (such as comments_count for a belonging Comment class) # is used on the associate class (such as a Post class). # # Option examples: # belongs_to :firm, :foreign_key => "client_of" # belongs_to :author, :class_name => "Person", :foreign_key => "author_id" # belongs_to :valid_coupon, :class_name => "Coupon", :foreign_key => "coupon_id", # :conditions => 'discounts > #{payments_count}' def belongs_to(association_id, options = {}) validate_options([ :class_name, :foreign_key, :remote, :conditions, :order, :dependent, :counter_cache ], options.keys) association_name, association_class_name, class_primary_key_name = associate_identification(association_id, options[:class_name], options[:foreign_key], false) require_association_class(association_class_name) association_class_primary_key_name = options[:foreign_key] || Inflector.underscore(Inflector.demodulize(association_class_name)) + "_id" if options[:remote] association_finder = <<-"end_eval" #{association_class_name}.find_first( "#{class_primary_key_name} = \#{quoted_id}#{options[:conditions] ? " AND " + options[:conditions] : ""}", #{options[:order] ? "\"" + options[:order] + "\"" : "nil" } ) end_eval else association_finder = options[:conditions] ? "#{association_class_name}.find_on_conditions(#{association_class_primary_key_name}, \"#{options[:conditions]}\")" : "#{association_class_name}.find(#{association_class_primary_key_name})" end has_association_method(association_name) association_reader_method(association_name, association_finder) belongs_to_writer_method(association_name, association_class_name, association_class_primary_key_name) association_comparison_method(association_name, association_class_name) if options[:counter_cache] module_eval( "after_create '#{association_class_name}.increment_counter(\"#{Inflector.pluralize(self.to_s.downcase). + "_count"}\", #{association_class_primary_key_name})" + " if has_#{association_name}?'" ) module_eval( "before_destroy '#{association_class_name}.decrement_counter(\"#{Inflector.pluralize(self.to_s.downcase) + "_count"}\", #{association_class_primary_key_name})" + " if has_#{association_name}?'" ) end end # 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 # will give the default join table name of "developers_projects" because "D" outranks "P". # # Any additional fields added to the join table will be placed as attributes when pulling records out through # has_and_belongs_to_many associations. This is helpful when have information about the association itself # that you want available on retrieval. Note that any fields in the join table will override matching field names # in the two joined tables. As a consequence, having an "id" field in the join table usually has the undesirable # result of clobbering the "id" fields in either of the other two tables. # # # Adds the following methods for retrieval and query. # +collection+ is replaced with the symbol passed as the first argument, so # has_and_belongs_to_many :categories would add among others +add_categories+. # * collection(force_reload = false) - returns an array of all the associated objects. # An empty array is returned if none is found. # * collection<<(object, ...) - adds one or more objects to the collection by creating associations in the join table # (collection.push and collection.concat are aliases to this method). # * collection.push_with_attributes(object, join_attributes) - adds one to the collection by creating an association in the join table that # also holds the attributes from join_attributes (should be a hash with the column names as keys). This can be used to have additional # attributes on the join, which will be injected into the associated objects when they are retrieved through the collection. # (collection.concat_with_attributes is an alias to this method). # * collection.delete(object, ...) - removes one or more objects from the collection by removing their associations from the join table. # This does not destroy the objects. # * 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. # # Example: An Developer class declares has_and_belongs_to_many :projects, which will add: # * Developer#projects # * Developer#projects<< # * Developer#projects.delete # * Developer#projects.clear # * Developer#projects.empty? # * Developer#projects.size # * Developer#projects.find(id) # The declaration may include an options hash to specialize the behavior of the association. # # Options are: # * :class_name - specify the class name of the association. Use it only if that name can't be infered # from the association name. So has_and_belongs_to_many :projects 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. # * :join_table - specify the name of the join table if the default based on lexical order isn't what you want. # WARNING: 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 # of this class in lower-case and "_id" suffixed. So a +Person+ class that makes a has_and_belongs_to_many association # will use "person_id" as the default foreign_key. # * :association_foreign_key - specify the association foreign key used for the association. By default this is # guessed to be the name of the associated class in lower-case and "_id" suffixed. So the associated class is +Project+ # that makes a has_and_belongs_to_many association will use "project_id" as the default association foreign_key. # * :conditions - specify the conditions that the associated object must meet in order to be included as a "WHERE" # sql fragment, such as "authorized = 1". # * :order - specify the order in which the associated objects are returned as a "ORDER BY" sql fragment, such as "last_name, first_name DESC" # * :uniq - if set to true, duplicate associated objects will be ignored by accessors and query methods # * :finder_sql - overwrite the default generated SQL used to fetch the association with a manual one # * :delete_sql - overwrite the default generated SQL used to remove links between the associated # classes with a manual one # * :insert_sql - overwrite the default generated SQL used to add links between the associated classes # with a manual one # # Option examples: # has_and_belongs_to_many :projects # has_and_belongs_to_many :nations, :class_name => "Country" # has_and_belongs_to_many :categories, :join_table => "prods_cats" def has_and_belongs_to_many(association_id, options = {}) validate_options([ :class_name, :table_name, :foreign_key, :association_foreign_key, :conditions, :join_table, :finder_sql, :delete_sql, :insert_sql, :order, :uniq ], options.keys) association_name, association_class_name, association_class_primary_key_name = associate_identification(association_id, options[:class_name], options[:foreign_key]) require_association_class(association_class_name) join_table = options[:join_table] || join_table_name(undecorated_table_name(self.to_s), undecorated_table_name(association_class_name)) define_method(association_name) do |*params| force_reload = params.first unless params.empty? association = instance_variable_get("@#{association_name}") if association.nil? association = HasAndBelongsToManyAssociation.new(self, association_name, association_class_name, association_class_primary_key_name, join_table, options) instance_variable_set("@#{association_name}", association) end association.reload if force_reload association end before_destroy_sql = "DELETE FROM #{join_table} WHERE #{association_class_primary_key_name} = \\\#{self.quoted_id}" module_eval(%{before_destroy "self.connection.delete(%{#{before_destroy_sql}})"}) # " # deprecated api deprecated_collection_count_method(association_name) deprecated_add_association_relation(association_name) deprecated_remove_association_relation(association_name) deprecated_has_collection_method(association_name) end private # Raises an exception if an invalid option has been specified to prevent misspellings from slipping through def validate_options(valid_option_keys, supplied_option_keys) unknown_option_keys = supplied_option_keys - valid_option_keys raise(ActiveRecord::ActiveRecordError, "Unknown options: #{unknown_option_keys}") unless unknown_option_keys.empty? end 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 def associate_identification(association_id, association_class_name, foreign_key, plural = true) if association_class_name !~ /::/ association_class_name = type_name_with_module( association_class_name || Inflector.camelize(plural ? Inflector.singularize(association_id.id2name) : association_id.id2name) ) end primary_key_name = foreign_key || Inflector.underscore(Inflector.demodulize(name)) + "_id" return association_id.id2name, association_class_name, primary_key_name end def association_comparison_method(association_name, association_class_name) module_eval <<-"end_eval", __FILE__, __LINE__ def #{association_name}?(comparison_object, force_reload = false) if comparison_object.kind_of?(#{association_class_name}) #{association_name}(force_reload) == comparison_object else raise "Comparison object is a #{association_class_name}, should have been \#{comparison_object.class.name}" end end end_eval end def association_reader_method(association_name, association_finder) module_eval <<-"end_eval", __FILE__, __LINE__ def #{association_name}(force_reload = false) if @#{association_name}.nil? || force_reload begin @#{association_name} = #{association_finder} rescue ActiveRecord::StatementInvalid, ActiveRecord::RecordNotFound nil end end return @#{association_name} end end_eval end def has_one_writer_method(association_name, association_class_name, class_primary_key_name) module_eval <<-"end_eval", __FILE__, __LINE__ def #{association_name}=(association) if association.nil? @#{association_name}.#{class_primary_key_name} = nil @#{association_name}.save(false) @#{association_name} = nil else raise ActiveRecord::AssociationTypeMismatch unless #{association_class_name} === association association.#{class_primary_key_name} = id association.save(false) @#{association_name} = association end end end_eval end def belongs_to_writer_method(association_name, association_class_name, association_class_primary_key_name) module_eval <<-"end_eval", __FILE__, __LINE__ def #{association_name}=(association) if association.nil? @#{association_name} = self.#{association_class_primary_key_name} = nil else raise ActiveRecord::AssociationTypeMismatch unless #{association_class_name} === association @#{association_name} = association self.#{association_class_primary_key_name} = association.id end end end_eval end def has_association_method(association_name) module_eval <<-"end_eval", __FILE__, __LINE__ def has_#{association_name}?(force_reload = false) !#{association_name}(force_reload).nil? end end_eval end def build_method(method_prefix, collection_name, collection_class_name, class_primary_key_name) module_eval <<-"end_eval", __FILE__, __LINE__ def #{method_prefix + collection_name}(attributes = {}) association = #{collection_class_name}.new association.attributes = attributes.merge({ "#{class_primary_key_name}" => id}) association end end_eval end def create_method(method_prefix, collection_name, collection_class_name, class_primary_key_name) module_eval <<-"end_eval", __FILE__, __LINE__ def #{method_prefix + collection_name}(attributes = nil) #{collection_class_name}.create((attributes || {}).merge({ "#{class_primary_key_name}" => id})) end end_eval end def require_association_class(class_name) require_association(Inflector.underscore(class_name)) if class_name end end end end