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