require 'active_record/associations/association_proxy' require 'active_record/associations/association_collection' require 'active_record/associations/belongs_to_association' require 'active_record/associations/belongs_to_polymorphic_association' require 'active_record/associations/has_one_association' require 'active_record/associations/has_many_association' require 'active_record/associations/has_many_through_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 unless self.new_record? 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 way 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#project_manager, Project#project_manager=(project_manager), Project#project_manager.nil?, # * 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:files/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) # ) # # == Unsaved objects and associations # # You can manipulate objects and associations before they are saved to the database, but there is some special behaviour you should be # aware of, mostly involving the saving of associated objects. # # === One-to-one associations # # * 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 (new_record? == true). # * If either of these saves fail (due to one of the objects being invalid) the assignment statement returns false and the assignment # is cancelled. # * If you wish to assign an object to a has_one association without saving it, use the #association.build 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 does # not save the parent either. # # === Collections # # * Adding an object to a collection (has_many or has_and_belongs_to_many) automatically saves that object, except if the parent object # (the owner of the collection) is not yet stored in the database. # * If saving any of the objects being added to a collection (via #push or similar) fails, then #push returns false. # * You can add an object to a collection without automatically saving it by using the #collection.build method (documented below). # * All unsaved (new_record? == true) members of the collection are automatically saved when the parent is saved. # # === Association callbacks # # Similiar to the normal callbacks that hook into the lifecycle of an Active Record object, you can also define callbacks that get # trigged when you add an object to or removing an object from a association collection. Example: # # class Project # has_and_belongs_to_many :developers, :after_add => :evaluate_velocity # # def evaluate_velocity(developer) # ... # end # end # # It's possible to stack callbacks by passing them as an array. Example: # # class Project # has_and_belongs_to_many :developers, :after_add => [:evaluate_velocity, Proc.new { |p, d| p.shipping_date = Time.now}] # end # # Possible callbacks are: before_add, after_add, before_remove and after_remove. # # 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. # # === Association extensions # # The proxy objects that controls the access to associations can be extended through anonymous modules. This is especially # 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 # # == 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 # # == Eager loading of associations # # Eager loading is a way to find objects of a certain class and a number of named associations along with it in a single SQL call. This is # one of the easiest ways of to prevent the dreaded 1+N problem in which fetching 100 posts that each needs to display their author # triggers 101 database queries. Through the use of eager loading, the 101 queries can be reduced to 1. Example: # # class Post < ActiveRecord::Base # belongs_to :author # has_many :comments # end # # Consider the following loop using the class above: # # for post in Post.find(:all) # puts "Post: " + post.title # puts "Written by: " + post.author.name # puts "Last comment on: " + post.comments.first.created_on # end # # 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) # # This references the name of the belongs_to association that also used the :author symbol, so the find will now weave in a join something # like this: LEFT OUTER JOIN authors ON authors.id = posts.author_id. Doing so will cut down the number of queries from 201 to 101. # # We can improve upon the situation further by referencing both associations in the finder with: # # for post in Post.find(:all, :include => [ :author, :comments ]) # # That'll add another join along the lines of: LEFT OUTER JOIN comments ON comments.post_id = posts.id. And we'll be down to 1 query. # But that shouldn't fool you to think that you can pull out huge amounts of data with no performance penalty just because you've reduced # 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. # # Please note that limited eager loading with has_many and has_and_belongs_to_many associations is not compatible with describing conditions # on these eager tables. This will work: # # Post.find(:all, :include => :comments, :conditions => "posts.title = 'magic forest'", :limit => 2) # # ...but this will not (and an ArgumentError will be raised): # # Post.find(:all, :include => :comments, :conditions => "comments.body like 'Normal%'", :limit => 2) # # Also have in mind that since the eager loading is pulling from multiple tables, you'll have to disambiguate any column references # in both conditions and orders. So :order => "posts.id DESC" will work while :order => "id DESC" will not. This may require that # you alter the :order and :conditions on the association definitions themselves. # # It's currently not possible to use eager loading on multiple associations from the same table. Eager loading will also not pull # additional attributes on join tables, so "rich associations" with has_and_belongs_to_many is not a good fit for eager loading. # # == 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 clients.empty?. # * 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 will also destroy the objects if they're declared as belongs_to and dependent on this model. # * collection=objects - replaces the collections content by deleting and adding objects as appropriate. # * 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 destroys the associated objects if they # are :dependent, deletes them directly from the database if they are :exclusively_dependent, # and sets their foreign keys to NULL otherwise. # * 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 Base.find. # * 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. *Note:* 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+ and linked to this object through a foreign key and that has already been saved (if it passed the validation). # *Note:* This only works if an associated object already exists, not if it's nil! # # Example: A Firm class declares has_many :clients, which will add: # * Firm#clients (similar to Clients.find :all, :conditions => "firm_id = #{id}") # * Firm#clients<< # * Firm#clients.delete # * Firm#clients= # * Firm#client_ids= # * 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(id, :conditions => "firm_id = #{id}")) # * Firm#clients.build (similar to Client.new("firm_id" => id)) # * Firm#clients.create (similar to c = Client.new("firm_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 inferred # 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" # * :group - specify the attribute by which the associated objects are returned as a "GROUP BY" sql fragment, # such as "category" # * :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 :destroy (or true) all the associated objects are destroyed # alongside this object by calling their destroy method. If set to :delete_all all associated # objects are deleted *without* calling their destroy method. If set to :nullify all associated # objects' foreign keys are set to NULL *without* calling their save callbacks. # May not be set if :exclusively_dependent is also set. # * :exclusively_dependent - Deprecated; equivalent to :dependent => :delete_all. 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 depend 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. # * :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 GROUP BY SQL-clause. # * :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 * as in SELECT * FROM, but can be changed if you for example want to do a join, but not # include the joined columns. # # 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 => 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 = {}, &extension) reflection = create_has_many_reflection(association_id, options, &extension) configure_dependency_for_has_many(reflection) if options[:through] collection_reader_method(reflection, HasManyThroughAssociation) else add_multiple_associated_save_callbacks(reflection.name) add_association_callbacks(reflection.name, reflection.options) collection_accessor_methods(reflection, HasManyAssociation) end add_deprecated_api_for_has_many(reflection.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 manager.nil?. # * 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.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. Note: 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+ 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, :conditions => "account_id = #{id}")) # * Account#beneficiary=(beneficiary) (similar to beneficiary.account_id = account.id; beneficiary.save) # * 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 inferred # 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 :destroy (or true) all the associated objects are destroyed when this object is. Also, # association is assigned. # * :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. # * :include - specify second-order associations that should be eager loaded when this object is loaded. # # 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 = {}) reflection = create_has_one_reflection(association_id, options) module_eval do after_save <<-EOF association = instance_variable_get("@#{reflection.name}") unless association.nil? association["#{reflection.primary_key_name}"] = id association.save(true) end EOF end association_accessor_methods(reflection, HasOneAssociation) association_constructor_method(:build, reflection, HasOneAssociation) association_constructor_method(:create, reflection, HasOneAssociation) configure_dependency_for_has_one(reflection) # deprecated api deprecated_has_association_method(reflection.name) deprecated_association_comparison_method(reflection.name, reflection.class_name) 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 author.nil?. # * 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.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: A Post class declares belongs_to :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? # * Post#build_author (similar to post.author = Author.new) # * Post#create_author (similar to post.author = Author.new; post.author.save; post.author) # 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 inferred # 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). # * :include - specify second-order associations that should be eager loaded when this object is loaded. # # 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 = {}) reflection = create_belongs_to_reflection(association_id, options) if reflection.options[:polymorphic] association_accessor_methods(reflection, BelongsToPolymorphicAssociation) module_eval do before_save <<-EOF association = instance_variable_get("@#{reflection.name}") if !association.nil? if association.new_record? association.save(true) end if association.updated? self["#{reflection.primary_key_name}"] = association.id self["#{reflection.options[:foreign_type]}"] = ActiveRecord::Base.send(:class_name_of_active_record_descendant, association.class).to_s end end EOF end else association_accessor_methods(reflection, BelongsToAssociation) association_constructor_method(:build, reflection, BelongsToAssociation) association_constructor_method(:create, reflection, BelongsToAssociation) module_eval do before_save <<-EOF association = instance_variable_get("@#{reflection.name}") if !association.nil? if association.new_record? association.save(true) end if association.updated? self["#{reflection.primary_key_name}"] = association.id end end EOF end if options[:counter_cache] module_eval( "after_create '#{reflection.class_name}.increment_counter(\"#{self.to_s.underscore.pluralize + "_count"}\", #{reflection.primary_key_name})" + " unless #{reflection.name}.nil?'" ) module_eval( "before_destroy '#{reflection.class_name}.decrement_counter(\"#{self.to_s.underscore.pluralize + "_count"}\", #{reflection.primary_key_name})" + " unless #{reflection.name}.nil?'" ) end # deprecated api deprecated_has_association_method(reflection.name) deprecated_association_comparison_method(reflection.name, reflection.class_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 categories.empty?. # * 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=objects - replaces the collections content by deleting and adding objects as appropriate. # * 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 # meets the condition that it has to be associated with this object. # # Example: An Developer class declares has_and_belongs_to_many :projects, which will add: # * Developer#projects # * Developer#projects<< # * Developer#projects.push_with_attributes # * Developer#projects.delete # * Developer#projects= # * Developer#project_ids= # * 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 inferred # 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 if the associated class is +Project+, # the 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 # * :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 GROUP BY SQL-clause. # * :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 * as in SELECT * FROM, but can be changed if you for example want to do a join, but not # include the joined columns. # # 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" # has_and_belongs_to_many :active_projects, :join_table => 'developers_projects', :delete_sql => # '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) add_multiple_associated_save_callbacks(reflection.name) 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}" class_eval <<-end_eval alias_method :#{old_method}, :destroy_without_callbacks def destroy_without_callbacks #{reflection.name}.clear #{old_method} end end_eval add_association_callbacks(reflection.name, options) # deprecated api deprecated_collection_count_method(reflection.name) deprecated_add_association_relation(reflection.name) deprecated_remove_association_relation(reflection.name) deprecated_has_collection_method(reflection.name) end private 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 association_accessor_methods(reflection, association_proxy_class) define_method(reflection.name) do |*params| force_reload = params.first unless params.empty? association = instance_variable_get("@#{reflection.name}") if association.nil? || force_reload association = association_proxy_class.new(self, reflection) retval = association.reload unless retval.nil? instance_variable_set("@#{reflection.name}", association) else instance_variable_set("@#{reflection.name}", nil) return nil end end association end define_method("#{reflection.name}=") do |new_value| association = instance_variable_get("@#{reflection.name}") if association.nil? association = association_proxy_class.new(self, reflection) end association.replace(new_value) unless new_value.nil? instance_variable_set("@#{reflection.name}", association) else instance_variable_set("@#{reflection.name}", nil) return nil end association end define_method("set_#{reflection.name}_target") do |target| return if target.nil? association = association_proxy_class.new(self, reflection) association.target = target instance_variable_set("@#{reflection.name}", association) end end def collection_reader_method(reflection, association_proxy_class) define_method(reflection.name) do |*params| force_reload = params.first unless params.empty? association = instance_variable_get("@#{reflection.name}") unless association.respond_to?(:loaded?) association = association_proxy_class.new(self, reflection) instance_variable_set("@#{reflection.name}", association) end association.reload if force_reload association end end def collection_accessor_methods(reflection, association_proxy_class) collection_reader_method(reflection, association_proxy_class) define_method("#{reflection.name}=") do |new_value| association = instance_variable_get("@#{reflection.name}") unless association.respond_to?(:loaded?) association = association_proxy_class.new(self, reflection) instance_variable_set("@#{reflection.name}", association) end association.replace(new_value) association end define_method("#{reflection.name.to_s.singularize}_ids=") do |new_value| send("#{reflection.name}=", reflection.class_name.constantize.find(new_value)) end end def require_association_class(class_name) require_association(Inflector.underscore(class_name)) if class_name end def add_multiple_associated_save_callbacks(association_name) method_name = "validate_associated_records_for_#{association_name}".to_sym define_method(method_name) do association = instance_variable_get("@#{association_name}") if association.respond_to?(:loaded?) if new_record? association else association.select { |record| record.new_record? } end.each do |record| errors.add "#{association_name}" unless record.valid? end end end validate method_name before_save("@new_record_before_save = new_record?; true") after_callback = <<-end_eval association = instance_variable_get("@#{association_name}") if association.respond_to?(:loaded?) if @new_record_before_save records_to_save = association else records_to_save = association.select { |record| record.new_record? } end records_to_save.each { |record| association.send(:insert_record, record) } association.send(:construct_sql) # reconstruct the SQL queries now that we know the owner's id end end_eval # Doesn't use after_save as that would save associations added in after_create/after_update twice after_create(after_callback) after_update(after_callback) end 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] association = instance_variable_get("@#{reflection.name}") if association.nil? association = association_proxy_class.new(self, reflection) instance_variable_set("@#{reflection.name}", association) end if association_proxy_class == HasOneAssociation association.send(constructor, attributees, replace_existing) else association.send(constructor, attributees) end end end def find_with_associations(options = {}) reflections = reflect_on_included_associations(options[:include]) guard_against_missing_reflections(reflections, options) schema_abbreviations = generate_schema_abbreviations(reflections) primary_key_table = generate_primary_key_table(reflections, schema_abbreviations) rows = select_all_rows(options, schema_abbreviations, reflections) records, records_in_order = { }, [] primary_key = primary_key_table[table_name] for row in rows id = row[primary_key] records_in_order << (records[id] = instantiate(extract_record(schema_abbreviations, table_name, row))) unless records[id] record = records[id] reflections.each do |reflection| case reflection.macro when :has_many, :has_and_belongs_to_many collection = record.send(reflection.name) collection.loaded next unless row[primary_key_table[reflection.table_name]] association = reflection.klass.send(:instantiate, extract_record(schema_abbreviations, reflection.table_name, row)) collection.target.push(association) unless collection.target.include?(association) when :has_one, :belongs_to next unless row[primary_key_table[reflection.table_name]] record.send( "set_#{reflection.name}_target", reflection.klass.send(:instantiate, extract_record(schema_abbreviations, reflection.table_name, row)) ) end end end return records_in_order end def configure_dependency_for_has_many(reflection) if reflection.options[:dependent] && reflection.options[:exclusively_dependent] raise ArgumentError, ':dependent and :exclusively_dependent are mutually exclusive options. You may specify one or the other.' end if reflection.options[:exclusively_dependent] reflection.options[:dependent] = :delete_all #warn "The :exclusively_dependent option is deprecated. Please use :dependent => :delete_all instead.") end # See HasManyAssociation#delete_records. Dependent associations # delete children, otherwise foreign key is set to NULL. case reflection.options[:dependent] when :destroy, true module_eval "before_destroy '#{reflection.name}.each { |o| o.destroy }'" when :delete_all module_eval "before_destroy { |record| #{reflection.class_name}.delete_all(%(#{reflection.primary_key_name} = \#{record.quoted_id})) }" when :nullify module_eval "before_destroy { |record| #{reflection.class_name}.update_all(%(#{reflection.primary_key_name} = NULL), %(#{reflection.primary_key_name} = \#{record.quoted_id})) }" when nil, false # pass else raise ArgumentError, 'The :dependent option expects either true, :destroy, :delete_all, or :nullify' end end def configure_dependency_for_has_one(reflection) case reflection.options[:dependent] when :destroy, true module_eval "before_destroy '#{reflection.name}.destroy unless #{reflection.name}.nil?'" when :nullify module_eval "before_destroy '#{reflection.name}.update_attribute(\"#{reflection.primary_key_name}\", nil)'" when nil, false # pass else raise ArgumentError, "The :dependent option expects either :destroy or :nullify." end end def add_deprecated_api_for_has_many(association_name) 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_collection_create_method(association_name) deprecated_collection_build_method(association_name) end def create_has_many_reflection(association_id, options, &extension) options.assert_valid_keys( :class_name, :table_name, :foreign_key, :exclusively_dependent, :dependent, :select, :conditions, :include, :order, :group, :limit, :offset, :as, :through, :finder_sql, :counter_sql, :before_add, :after_add, :before_remove, :after_remove, :extend ) options[:extend] = create_extension_module(association_id, extension) if block_given? reflection = create_reflection(:has_many, association_id, options, self) reflection.require_class reflection end def create_has_one_reflection(association_id, options) options.assert_valid_keys( :class_name, :foreign_key, :remote, :conditions, :order, :include, :dependent, :counter_cache, :extend ) reflection = create_reflection(:has_one, association_id, options, self) reflection.require_class reflection end def create_belongs_to_reflection(association_id, options) options.assert_valid_keys( :class_name, :foreign_key, :foreign_type, :remote, :conditions, :order, :include, :dependent, :counter_cache, :extend, :polymorphic ) reflection = create_reflection(:belongs_to, association_id, options, self) if options[:polymorphic] reflection.options[:foreign_type] ||= reflection.class_name.underscore + "_type" else reflection.require_class end reflection end def create_has_and_belongs_to_many_reflection(association_id, options, &extension) options.assert_valid_keys( :class_name, :table_name, :join_table, :foreign_key, :association_foreign_key, :select, :conditions, :include, :order, :group, :limit, :offset, :finder_sql, :delete_sql, :insert_sql, :uniq, :before_add, :after_add, :before_remove, :after_remove, :extend ) options[:extend] = create_extension_module(association_id, extension) if block_given? reflection = create_reflection(:has_and_belongs_to_many, association_id, options, self) reflection.require_class reflection.options[:join_table] ||= join_table_name(undecorated_table_name(self.to_s), undecorated_table_name(reflection.class_name)) reflection end def reflect_on_included_associations(associations) [ associations ].flatten.collect { |association| reflect_on_association(association.to_s.intern) } end def guard_against_missing_reflections(reflections, options) reflections.each do |r| raise( ConfigurationError, "Association was not found; perhaps you misspelled it? " + "You specified :include => :#{[options[:include]].flatten.join(', :')}" ) if r.nil? end end def guard_against_unlimitable_reflections(reflections, options) if (options[:offset] || options[:limit]) && !using_limitable_reflections?(reflections) raise( ConfigurationError, "You can not use offset and limit together with has_many or has_and_belongs_to_many associations" ) end end def generate_schema_abbreviations(reflections) schema = [ [ table_name, column_names ] ] schema += reflections.collect { |r| [ r.table_name, r.klass.column_names ] } schema_abbreviations = {} schema.each_with_index do |table_and_columns, i| table, columns = table_and_columns columns.each_with_index { |column, j| schema_abbreviations["t#{i}_r#{j}"] = [ table, column ] } end return schema_abbreviations end def generate_primary_key_table(reflections, schema_abbreviations) primary_key_lookup_table = {} primary_key_lookup_table[table_name] = schema_abbreviations.find { |cn, tc| tc == [ table_name, primary_key ] }.first reflections.collect do |reflection| primary_key_lookup_table[reflection.klass.table_name] = schema_abbreviations.find { |cn, tc| tc == [ reflection.klass.table_name, reflection.klass.primary_key ] }.first end return primary_key_lookup_table end def select_all_rows(options, schema_abbreviations, reflections) connection.select_all( construct_finder_sql_with_included_associations(options, schema_abbreviations, reflections), "#{name} Load Including Associations" ) end def construct_finder_sql_with_included_associations(options, schema_abbreviations, reflections) sql = "SELECT #{column_aliases(schema_abbreviations)} FROM #{table_name} " sql << reflections.collect { |reflection| association_join(reflection) }.to_s sql << "#{options[:joins]} " if options[:joins] add_conditions!(sql, options[:conditions]) add_sti_conditions!(sql, reflections) add_limited_ids_condition!(sql, options) if !using_limitable_reflections?(reflections) && options[:limit] sql << "ORDER BY #{options[:order]} " if options[:order] add_limit!(sql, options) if using_limitable_reflections?(reflections) return sanitize_sql(sql) end def add_limited_ids_condition!(sql, options) unless (id_list = select_limited_ids_list(options)).empty? sql << "#{condition_word(sql)} #{table_name}.#{primary_key} IN (#{id_list}) " end end def select_limited_ids_list(options) connection.select_values( construct_finder_sql_for_association_limiting(options), "#{name} Load IDs For Limited Eager Loading" ).collect { |id| connection.quote(id) }.join(", ") end def construct_finder_sql_for_association_limiting(options) raise(ArgumentError, "Limited eager loads and conditions on the eager tables is incompatible") if include_eager_conditions?(options) sql = "SELECT #{primary_key} FROM #{table_name} " add_conditions!(sql, options[:conditions]) sql << "ORDER BY #{options[:order]} " if options[:order] add_limit!(sql, options) return sanitize_sql(sql) end def include_eager_conditions?(options) conditions = options[:conditions] return false unless conditions conditions = conditions.first if conditions.is_a?(Array) conditions.scan(/(\w+)\.\w+/).flatten.any? do |condition_table_name| condition_table_name != table_name end end def using_limitable_reflections?(reflections) reflections.reject { |r| [ :belongs_to, :has_one ].include?(r.macro) }.length.zero? end def add_sti_conditions!(sql, reflections) sti_conditions = reflections.collect do |reflection| reflection.klass.send(:type_condition) unless reflection.klass.descends_from_active_record? end.compact unless sti_conditions.empty? sql << condition_word(sql) + sti_conditions.join(" AND ") end end def column_aliases(schema_abbreviations) schema_abbreviations.collect { |cn, tc| "#{tc[0]}.#{connection.quote_column_name tc[1]} AS #{cn}" }.join(", ") end def association_join(reflection) case reflection.macro when :has_and_belongs_to_many " LEFT OUTER JOIN #{reflection.options[:join_table]} ON " + "#{reflection.options[:join_table]}.#{reflection.options[:foreign_key] || table_name.classify.foreign_key} = " + "#{table_name}.#{primary_key} " + " LEFT OUTER JOIN #{reflection.klass.table_name} ON " + "#{reflection.options[:join_table]}.#{reflection.options[:association_foreign_key] || reflection.klass.table_name.classify.foreign_key} = " + "#{reflection.klass.table_name}.#{reflection.klass.primary_key} " when :has_many, :has_one " LEFT OUTER JOIN #{reflection.klass.table_name} ON " + "#{reflection.klass.table_name}.#{reflection.options[:foreign_key] || table_name.classify.foreign_key} = " + "#{table_name}.#{primary_key} " when :belongs_to " LEFT OUTER JOIN #{reflection.klass.table_name} ON " + "#{reflection.klass.table_name}.#{reflection.klass.primary_key} = " + "#{table_name}.#{reflection.options[:foreign_key] || reflection.klass.table_name.classify.foreign_key} " else "" end end def add_association_callbacks(association_name, options) callbacks = %w(before_add after_add before_remove after_remove) callbacks.each do |callback_name| full_callback_name = "#{callback_name.to_s}_for_#{association_name.to_s}" defined_callbacks = options[callback_name.to_sym] if options.has_key?(callback_name.to_sym) class_inheritable_reader full_callback_name.to_sym write_inheritable_array(full_callback_name.to_sym, [defined_callbacks].flatten) end end end def extract_record(schema_abbreviations, table_name, row) record = {} row.each do |column, value| prefix, column_name = schema_abbreviations[column] record[column_name] = value if prefix == table_name end return record end def condition_word(sql) sql =~ /where/i ? " AND " : "WHERE " end def create_extension_module(association_id, extension) extension_module_name = "#{self.to_s}#{association_id.to_s.camelize}AssociationExtension" silence_warnings do Object.const_set(extension_module_name, Module.new(&extension)) end extension_module_name.constantize end end end end