--- /dev/null
+require 'active_record/associations/association_proxy'
+require 'active_record/associations/association_collection'
+require 'active_record/associations/belongs_to_association'
+require 'active_record/associations/belongs_to_polymorphic_association'
+require 'active_record/associations/has_one_association'
+require 'active_record/associations/has_many_association'
+require 'active_record/associations/has_many_through_association'
+require 'active_record/associations/has_and_belongs_to_many_association'
+require 'active_record/associations/has_one_through_association'
+
+module ActiveRecord
+ 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 :connector => 'or'} in model #{through_reflection.klass}. Try 'has_many #{reflection.name.inspect}, :through => #{through_reflection.name.inspect}, :source => <name>'. Is it one of #{source_associations.to_sentence :connector => 'or'}?")
+ 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 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:
+ def self.included(base)
+ base.extend(ClassMethods)
+ end
+
+ # Clears out the association cache
+ def clear_association_cache #:nodoc:
+ self.class.reflect_on_all_associations.to_a.each do |assoc|
+ instance_variable_set "@#{assoc.name}", nil
+ end unless self.new_record?
+ end
+
+ # Associations are a set of macro-like class methods for tying objects together through foreign keys. They express relationships like
+ # "Project has one Project Manager" or "Project belongs to a Portfolio". Each macro adds a number of methods to the class which are
+ # specialized according to the collection or association symbol and the options hash. It works much the same way as Ruby's own <tt>attr*</tt>
+ # 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:
+ # * <tt>Project#portfolio, Project#portfolio=(portfolio), Project#portfolio.nil?</tt>
+ # * <tt>Project#project_manager, Project#project_manager=(project_manager), Project#project_manager.nil?,</tt>
+ # * <tt>Project#milestones.empty?, Project#milestones.size, Project#milestones, Project#milestones<<(milestone),</tt>
+ # <tt>Project#milestones.delete(milestone), Project#milestones.find(milestone_id), Project#milestones.find(:all, options),</tt>
+ # <tt>Project#milestones.build, Project#milestones.create</tt>
+ # * <tt>Project#categories.empty?, Project#categories.size, Project#categories, Project#categories<<(category1),</tt>
+ # <tt>Project#categories.delete(category1)</tt>
+ #
+ # === 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
+ # #other.nil? | X | 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.exist? | 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 <tt>:through</tt> 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 <tt>has_many :through</tt>. 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.
+ #
+ # === 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 (<tt>new_record? == true</tt>).
+ # * 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 <tt>association.build</tt> 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 <tt>push</tt> or similar) fails, then <tt>push</tt> returns +false+.
+ # * You can add an object to a collection without automatically saving it by using the <tt>collection.build</tt> method (documented below).
+ # * All unsaved (<tt>new_record? == true</tt>) 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 <tt>:extend</tt> 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 <tt>:through</tt> 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 <tt>:author</tt> 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])
+ #
+ # will result in a single SQL query with joins along the lines of: <tt>LEFT OUTER JOIN comments ON comments.post_id = posts.id</tt> and
+ # <tt>LEFT OUTER JOIN authors ON authors.id = posts.author_id</tt>. 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
+ # <tt>:order => "author.name DESC"</tt> will work but <tt>:order => "name DESC"</tt> will not.
+ #
+ # If you do want eagerload only some members of an association it is usually more natural to <tt>:include</tt> 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)
+ #
+ # 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 <tt>:limit</tt> 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)
+ #
+ # 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 <tt>#{reflection_name}_#{parent_table_name}</tt>. 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 <tt>_join</tt> 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 <tt>:joins</tt> 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 <tt>Firm#clients</tt> is called, it will in turn call <tt>MyApplication::Business::Client.find_all_by_firm_id(firm.id)</tt>.
+ # 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
+ #
+ # == Type safety with <tt>ActiveRecord::AssociationTypeMismatch</tt>
+ #
+ # If you attempt to assign an object to an association that doesn't match the inferred or specified <tt>:class_name</tt>, you'll
+ # get an <tt>ActiveRecord::AssociationTypeMismatch</tt>.
+ #
+ # == 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 <tt>:dependent => :destroy</tt>,
+ # and deleted if they're associated with <tt>:dependent => :delete_all</tt>.
+ # [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 <tt>:dependent => :destroy</tt>, deletes them directly from the
+ # database if <tt>:dependent => :delete_all</tt>, 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.exist?(...)]
+ # 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. <b>Note:</b> 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). <b>Note:</b> 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
+ # <tt>has_many :clients</tt> would add among others <tt>clients.empty?</tt>.)
+ #
+ # === Example
+ #
+ # Example: A Firm class declares <tt>has_many :clients</tt>, which will add:
+ # * <tt>Firm#clients</tt> (similar to <tt>Clients.find :all, :conditions => ["firm_id = ?", id]</tt>)
+ # * <tt>Firm#clients<<</tt>
+ # * <tt>Firm#clients.delete</tt>
+ # * <tt>Firm#clients=</tt>
+ # * <tt>Firm#client_ids</tt>
+ # * <tt>Firm#client_ids=</tt>
+ # * <tt>Firm#clients.clear</tt>
+ # * <tt>Firm#clients.empty?</tt> (similar to <tt>firm.clients.size == 0</tt>)
+ # * <tt>Firm#clients.size</tt> (similar to <tt>Client.count "firm_id = #{id}"</tt>)
+ # * <tt>Firm#clients.find</tt> (similar to <tt>Client.find(id, :conditions => "firm_id = #{id}")</tt>)
+ # * <tt>Firm#clients.exist?(:name => 'ACME')</tt> (similar to <tt>Client.exist?(:name => 'ACME', :firm_id => firm.id)</tt>)
+ # * <tt>Firm#clients.build</tt> (similar to <tt>Client.new("firm_id" => id)</tt>)
+ # * <tt>Firm#clients.create</tt> (similar to <tt>c = Client.new("firm_id" => id); c.save; c</tt>)
+ # 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 <tt>has_many :products</tt> 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 <tt>price > 5 AND name LIKE 'B%'</tt>. Record creations from the association are scoped if a hash
+ # is used. <tt>has_many :posts, :conditions => {:published => true}</tt> will create published posts with <tt>@blog.posts.create</tt>
+ # or <tt>@blog.posts.build</tt>.
+ # [:order]
+ # Specify the order in which the associated objects are returned as an <tt>ORDER BY</tt> SQL fragment,
+ # such as <tt>last_name, first_name DESC</tt>.
+ # [: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 <tt>:foreign_key</tt>.
+ # [:primary_key]
+ # Specify the method that returns the primary key used for the association. By default this is +id+.
+ # [:dependent]
+ # If set to <tt>:destroy</tt> all the associated objects are destroyed
+ # alongside this object by calling their +destroy+ method. If set to <tt>:delete_all</tt> all associated
+ # objects are deleted *without* calling their +destroy+ method. If set to <tt>:nullify</tt> all associated
+ # objects' foreign keys are set to +NULL+ *without* calling their +save+ callbacks. *Warning:* This option is ignored when also using
+ # the <tt>:through</tt> 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 <tt>:finder_sql</tt> is
+ # specified but not <tt>:counter_sql</tt>, <tt>:counter_sql</tt> will be generated by replacing <tt>SELECT ... FROM</tt> with <tt>SELECT COUNT(*) FROM</tt>.
+ # [: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 <tt>GROUP BY</tt> 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 <tt>*</tt> as in <tt>SELECT * FROM</tt>, 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 <tt>belongs_to</tt>).
+ # [:through]
+ # Specifies a Join Model through which to perform the query. Options for <tt>:class_name</tt> and <tt>:foreign_key</tt>
+ # are ignored, as the association uses the source reflection. You can only use a <tt>:through</tt> query through a <tt>belongs_to</tt>
+ # or <tt>has_many</tt> association on the join model.
+ # [:source]
+ # Specifies the source association name used by <tt>has_many :through</tt> queries. Only use it if the name cannot be
+ # inferred from the association. <tt>has_many :subscribers, :through => :subscriptions</tt> will look for either <tt>:subscribers</tt> or
+ # <tt>:subscriber</tt> on Subscription, unless a <tt>:source</tt> is given.
+ # [:source_type]
+ # Specifies type of the source association used by <tt>has_many :through</tt> queries where the source
+ # association is a polymorphic +belongs_to+.
+ # [:uniq]
+ # If true, duplicates will be omitted from the collection. Useful in conjunction with <tt>:through</tt>.
+ # [: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.
+ # 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_multiple_associated_validation_callbacks(reflection.name) unless options[:validate] == false
+ add_multiple_associated_save_callbacks(reflection.name)
+ 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.
+ # [association.nil?]
+ # Returns +true+ if there is no associated object.
+ # [build_association(attributes = {})]
+ # Returns a new object of the associated type that has been instantiated
+ # with +attributes+ and linked to this object through a foreign key, but has not
+ # yet been saved. <b>Note:</b> 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
+ # <tt>has_one :manager</tt> would add among others <tt>manager.nil?</tt>.)
+ #
+ # === Example
+ #
+ # An Account class declares <tt>has_one :beneficiary</tt>, which will add:
+ # * <tt>Account#beneficiary</tt> (similar to <tt>Beneficiary.find(:first, :conditions => "account_id = #{id}")</tt>)
+ # * <tt>Account#beneficiary=(beneficiary)</tt> (similar to <tt>beneficiary.account_id = account.id; beneficiary.save</tt>)
+ # * <tt>Account#beneficiary.nil?</tt>
+ # * <tt>Account#build_beneficiary</tt> (similar to <tt>Beneficiary.new("account_id" => id)</tt>)
+ # * <tt>Account#create_beneficiary</tt> (similar to <tt>b = Beneficiary.new("account_id" => id); b.save; b</tt>)
+ #
+ # === 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 <tt>has_one :manager</tt> 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 <tt>rank = 5</tt>.
+ # [:order]
+ # Specify the order in which the associated objects are returned as an <tt>ORDER BY</tt> SQL fragment,
+ # such as <tt>last_name, first_name DESC</tt>.
+ # [:dependent]
+ # If set to <tt>:destroy</tt>, the associated object is destroyed when this object is. If set to
+ # <tt>:delete</tt>, the associated object is deleted *without* calling its destroy method. If set to <tt>:nullify</tt>, 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 <tt>:foreign_key</tt>.
+ # [: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 <tt>belongs_to</tt>).
+ # [:select]
+ # By default, this is <tt>*</tt> as in <tt>SELECT * FROM</tt>, 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 <tt>:class_name</tt> and <tt>:foreign_key</tt>
+ # are ignored, as the association uses the source reflection. You can only use a <tt>:through</tt> query through a
+ # <tt>has_one</tt> or <tt>belongs_to</tt> association on the join model.
+ # [:source]
+ # Specifies the source association name used by <tt>has_one :through</tt> queries. Only use it if the name cannot be
+ # inferred from the association. <tt>has_one :favorite, :through => :favorites</tt> will look for a
+ # <tt>:favorite</tt> on Favorite, unless a <tt>:source</tt> is given.
+ # [:source_type]
+ # Specifies type of the source association used by <tt>has_one :through</tt> 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.
+ #
+ # 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)
+
+ ivar = "@#{reflection.name}"
+
+ method_name = "has_one_after_save_for_#{reflection.name}".to_sym
+ define_method(method_name) do
+ association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
+
+ if !association.nil? && (new_record? || association.new_record? || association[reflection.primary_key_name] != id)
+ association[reflection.primary_key_name] = id
+ association.save(true)
+ end
+ end
+ after_save method_name
+
+ add_single_associated_validation_callbacks(reflection.name) if options[:validate] == true
+ 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.
+ # [association.nil?]
+ # Returns +true+ if there is no associated object.
+ # [build_association(attributes = {})]
+ # Returns a new object of the associated type that has been instantiated
+ # with +attributes+ and linked to this object through a foreign key, but has not yet been saved.
+ # [create_association(attributes = {})]
+ # Returns a new object of the associated type that has been instantiated
+ # with +attributes+, 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
+ # <tt>belongs_to :author</tt> would add among others <tt>author.nil?</tt>.)
+ #
+ # === Example
+ #
+ # A Post class declares <tt>belongs_to :author</tt>, which will add:
+ # * <tt>Post#author</tt> (similar to <tt>Author.find(author_id)</tt>)
+ # * <tt>Post#author=(author)</tt> (similar to <tt>post.author_id = author.id</tt>)
+ # * <tt>Post#author?</tt> (similar to <tt>post.author == some_author</tt>)
+ # * <tt>Post#author.nil?</tt>
+ # * <tt>Post#build_author</tt> (similar to <tt>post.author = Author.new</tt>)
+ # * <tt>Post#create_author</tt> (similar to <tt>post.author = Author.new; post.author.save; post.author</tt>)
+ # 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 <tt>has_one :author</tt> 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 <tt>authorized = 1</tt>.
+ # [:select]
+ # By default, this is <tt>*</tt> as in <tt>SELECT * FROM</tt>, 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 <tt>belongs_to :person</tt> association will use
+ # "person_id" as the default <tt>:foreign_key</tt>. Similarly, <tt>belongs_to :favorite_person, :class_name => "Person"</tt>
+ # will use a foreign key of "favorite_person_id".
+ # [:dependent]
+ # If set to <tt>:destroy</tt>, the associated object is destroyed when this object is. If set to
+ # <tt>:delete</tt>, the associated object is deleted *without* calling its destroy method. This option should not be specified when
+ # <tt>belongs_to</tt> is used in conjunction with a <tt>has_many</tt> 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 <tt>#{table_name}_count</tt> (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., <tt>:counter_cache => :my_custom_counter</tt>.)
+ # 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. <tt>class Post; attr_readonly :comments_count; end</tt>).
+ # [: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.
+ #
+ # Option examples:
+ # belongs_to :firm, :foreign_key => "client_of"
+ # belongs_to :author, :class_name => "Person", :foreign_key => "author_id"
+ # belongs_to :valid_coupon, :class_name => "Coupon", :foreign_key => "coupon_id",
+ # :conditions => 'discounts > #{payments_count}'
+ # belongs_to :attachable, :polymorphic => true
+ # belongs_to :project, :readonly => true
+ # belongs_to :post, :counter_cache => true
+ def belongs_to(association_id, options = {})
+ reflection = create_belongs_to_reflection(association_id, options)
+
+ ivar = "@#{reflection.name}"
+
+ if reflection.options[:polymorphic]
+ association_accessor_methods(reflection, BelongsToPolymorphicAssociation)
+
+ method_name = "polymorphic_belongs_to_before_save_for_#{reflection.name}".to_sym
+ define_method(method_name) do
+ association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
+
+ if association && association.target
+ if association.new_record?
+ association.save(true)
+ end
+
+ if association.updated?
+ self[reflection.primary_key_name] = association.id
+ self[reflection.options[:foreign_type]] = association.class.base_class.name.to_s
+ end
+ end
+ end
+ before_save method_name
+ else
+ association_accessor_methods(reflection, BelongsToAssociation)
+ association_constructor_method(:build, reflection, BelongsToAssociation)
+ association_constructor_method(:create, reflection, BelongsToAssociation)
+
+ method_name = "belongs_to_before_save_for_#{reflection.name}".to_sym
+ define_method(method_name) do
+ association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
+
+ if !association.nil?
+ if association.new_record?
+ association.save(true)
+ end
+
+ if association.updated?
+ self[reflection.primary_key_name] = association.id
+ end
+ end
+ end
+ before_save method_name
+ end
+
+ # Create the callbacks to update counter cache
+ if options[:counter_cache]
+ cache_column = options[:counter_cache] == true ?
+ "#{self.to_s.demodulize.underscore.pluralize}_count" :
+ options[:counter_cache]
+
+ 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, send(reflection.primary_key_name)) 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, send(reflection.primary_key_name)) 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
+
+ add_single_associated_validation_callbacks(reflection.name) if options[:validate] == true
+
+ 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 <tt><</tt> 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 <tt>:join_table</tt> option if you need to.
+ #
+ # 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
+ # (<tt>collection.push</tt> and <tt>collection.concat</tt> 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.exist?(...)]
+ # 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
+ # <tt>has_and_belongs_to_many :categories</tt> would add among others <tt>categories.empty?</tt>.)
+ #
+ # === Example
+ #
+ # A Developer class declares <tt>has_and_belongs_to_many :projects</tt>, which will add:
+ # * <tt>Developer#projects</tt>
+ # * <tt>Developer#projects<<</tt>
+ # * <tt>Developer#projects.delete</tt>
+ # * <tt>Developer#projects=</tt>
+ # * <tt>Developer#project_ids</tt>
+ # * <tt>Developer#project_ids=</tt>
+ # * <tt>Developer#projects.clear</tt>
+ # * <tt>Developer#projects.empty?</tt>
+ # * <tt>Developer#projects.size</tt>
+ # * <tt>Developer#projects.find(id)</tt>
+ # * <tt>Developer#clients.exist?(...)</tt>
+ # * <tt>Developer#projects.build</tt> (similar to <tt>Project.new("project_id" => id)</tt>)
+ # * <tt>Developer#projects.create</tt> (similar to <tt>c = Project.new("project_id" => id); c.save; c</tt>)
+ # 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 <tt>has_and_belongs_to_many :projects</tt> 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.
+ # <b>WARNING:</b> If you're overwriting the table name of either class, the +table_name+ method
+ # MUST be declared underneath any +has_and_belongs_to_many+ declaration in order to work.
+ # [:foreign_key]
+ # Specify the foreign key used for the association. By default this is guessed to be the name
+ # of this class in lower-case and "_id" suffixed. So a Person class that makes a +has_and_belongs_to_many+ association
+ # will use "person_id" as the default <tt>:foreign_key</tt>.
+ # [:association_foreign_key]
+ # Specify the association foreign key used for the association. By default this is
+ # guessed to be the name of the associated class in lower-case and "_id" suffixed. So if the associated class is Project,
+ # the +has_and_belongs_to_many+ association will use "project_id" as the default <tt>:association_foreign_key</tt>.
+ # [:conditions]
+ # Specify the conditions that the associated object must meet in order to be included as a +WHERE+
+ # SQL fragment, such as <tt>authorized = 1</tt>. Record creations from the association are scoped if a hash is used.
+ # <tt>has_many :posts, :conditions => {:published => true}</tt> will create published posts with <tt>@blog.posts.create</tt>
+ # or <tt>@blog.posts.build</tt>.
+ # [:order]
+ # Specify the order in which the associated objects are returned as an <tt>ORDER BY</tt> SQL fragment,
+ # such as <tt>last_name, first_name DESC</tt>
+ # [: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 <tt>:finder_sql</tt> is
+ # specified but not <tt>:counter_sql</tt>, <tt>:counter_sql</tt> will be generated by replacing <tt>SELECT ... FROM</tt> with <tt>SELECT COUNT(*) FROM</tt>.
+ # [: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 <tt>GROUP BY</tt> 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 <tt>*</tt> as in <tt>SELECT * FROM</tt>, 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.
+ #
+ # 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)
+
+ add_multiple_associated_validation_callbacks(reflection.name) unless options[:validate] == false
+ add_multiple_associated_save_callbacks(reflection.name)
+ collection_accessor_methods(reflection, HasAndBelongsToManyAssociation)
+
+ # Don't use a before_destroy callback since users' before_destroy
+ # callbacks will be executed after the association is wiped out.
+ old_method = "destroy_without_habtm_shim_for_#{reflection.name}"
+ class_eval <<-end_eval unless method_defined?(old_method)
+ alias_method :#{old_method}, :destroy_without_callbacks
+ def destroy_without_callbacks
+ #{reflection.name}.clear
+ #{old_method}
+ end
+ end_eval
+
+ add_association_callbacks(reflection.name, options)
+ end
+
+ private
+ # Generates a join table name from two provided table names.
+ # The names in the join table namesme 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)
+ ivar = "@#{reflection.name}"
+
+ define_method(reflection.name) do |*params|
+ force_reload = params.first unless params.empty?
+
+ association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
+
+ if association.nil? || force_reload
+ association = association_proxy_class.new(self, reflection)
+ retval = association.reload
+ if retval.nil? and association_proxy_class == BelongsToAssociation
+ instance_variable_set(ivar, nil)
+ return nil
+ end
+ instance_variable_set(ivar, association)
+ end
+
+ association.target.nil? ? nil : association
+ end
+
+ define_method("loaded_#{reflection.name}?") do
+ association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
+ association && association.loaded?
+ end
+
+ define_method("#{reflection.name}=") do |new_value|
+ association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
+
+ if association.nil? || association.target != new_value
+ association = association_proxy_class.new(self, reflection)
+ end
+
+ if association_proxy_class == HasOneThroughAssociation
+ association.create_through_record(new_value)
+ self.send(reflection.name, new_value)
+ else
+ association.replace(new_value)
+ instance_variable_set(ivar, new_value.nil? ? nil : association)
+ end
+ 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
+ instance_variable_set(ivar, association)
+ end
+ end
+
+ def collection_reader_method(reflection, association_proxy_class)
+ define_method(reflection.name) do |*params|
+ ivar = "@#{reflection.name}"
+
+ force_reload = params.first unless params.empty?
+ association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
+
+ unless association.respond_to?(:loaded?)
+ association = association_proxy_class.new(self, reflection)
+ instance_variable_set(ivar, 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
+ send(reflection.name).all(:select => "#{reflection.quoted_table_name}.#{reflection.klass.primary_key}").map(&:id)
+ 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 add_single_associated_validation_callbacks(association_name)
+ method_name = "validate_associated_records_for_#{association_name}".to_sym
+ define_method(method_name) do
+ association = instance_variable_get("@#{association_name}")
+ if !association.nil?
+ errors.add association_name unless association.target.nil? || association.valid?
+ end
+ end
+
+ validate method_name
+ end
+
+ def add_multiple_associated_validation_callbacks(association_name)
+ method_name = "validate_associated_records_for_#{association_name}".to_sym
+ ivar = "@#{association_name}"
+
+ define_method(method_name) do
+ association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
+
+ if association.respond_to?(:loaded?)
+ if new_record?
+ association
+ elsif association.loaded?
+ association.select { |record| record.new_record? }
+ else
+ association.target.select { |record| record.new_record? }
+ end.each do |record|
+ errors.add association_name unless record.valid?
+ end
+ end
+ end
+
+ validate method_name
+ end
+
+ def add_multiple_associated_save_callbacks(association_name)
+ ivar = "@#{association_name}"
+
+ method_name = "before_save_associated_records_for_#{association_name}".to_sym
+ define_method(method_name) do
+ @new_record_before_save = new_record?
+ true
+ end
+ before_save method_name
+
+ method_name = "after_create_or_update_associated_records_for_#{association_name}".to_sym
+ define_method(method_name) do
+ association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
+
+ records_to_save = if @new_record_before_save
+ association
+ elsif association.respond_to?(:loaded?) && association.loaded?
+ association.select { |record| record.new_record? }
+ elsif association.respond_to?(:loaded?) && !association.loaded?
+ association.target.select { |record| record.new_record? }
+ else
+ []
+ end
+ records_to_save.each { |record| association.send(:insert_record, record) } unless records_to_save.blank?
+
+ # reconstruct the SQL queries now that we know the owner's id
+ association.send(:construct_sql) if association.respond_to?(:construct_sql)
+ end
+
+ # Doesn't use after_save as that would save associations added in after_create/after_update twice
+ after_create method_name
+ after_update method_name
+ end
+
+ def association_constructor_method(constructor, reflection, association_proxy_class)
+ define_method("#{constructor}_#{reflection.name}") do |*params|
+ ivar = "@#{reflection.name}"
+
+ attributees = params.first unless params.empty?
+ replace_existing = params[1].nil? ? true : params[1]
+ association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
+
+ if association.nil?
+ association = association_proxy_class.new(self, reflection)
+ instance_variable_set(ivar, association)
+ end
+
+ if association_proxy_class == HasOneAssociation
+ association.send(constructor, attributees, replace_existing)
+ else
+ association.send(constructor, attributees)
+ end
+ end
+ end
+
+ def find_with_associations(options = {})
+ 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]) if reflection.options[:conditions]
+ dependent_conditions << extra_conditions if extra_conditions
+ dependent_conditions = dependent_conditions.collect {|where| "(#{where})" }.join(" AND ")
+
+ 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|
+ delete_all_has_many_dependencies(record,
+ "#{reflection.name}",
+ #{reflection.class_name},
+ "#{dependent_conditions}")
+ end
+ }
+ when :nullify
+ module_eval %Q{
+ before_destroy do |record|
+ nullify_has_many_dependencies(record,
+ "#{reflection.name}",
+ #{reflection.class_name},
+ "#{reflection.primary_key_name}",
+ "#{dependent_conditions}")
+ 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
+ before_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
+ before_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, :limit, :offset,
+ :as, :through, :source, :source_type,
+ :uniq,
+ :finder_sql, :counter_sql,
+ :before_add, :after_add, :before_remove, :after_remove,
+ :extend, :readonly,
+ :validate
+ ]
+
+ 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
+ ]
+
+ 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, :foreign_key, :foreign_type, :remote, :select, :conditions,
+ :include, :dependent, :counter_cache, :extend, :polymorphic, :readonly,
+ :validate
+ ]
+
+ 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, :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)
+
+ 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], 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], 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 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 << cond.first
+ else all << cond
+ end
+ end
+ conditions.join(' ').scan(/([\.a-zA-Z_]+).?\./).flatten
+ end
+
+ def order_tables(options)
+ order = [options[:order], scope(:find, :order) ].join(", ")
+ return [] unless order && order.is_a?(String)
+ order.scan(/([\.a-zA-Z_]+).?\./).flatten
+ end
+
+ def selects_tables(options)
+ select = options[:select]
+ return [] unless select && select.is_a?(String)
+ select.scan(/"?([\.a-zA-Z_]+)"?.?\./).flatten
+ end
+
+ # Checks if the conditions reference a table other than the current model table
+ def include_eager_conditions?(options, tables = nil)
+ ((tables || conditions_tables(options)) - [table_name]).any?
+ end
+
+ # Checks if the query order references a table other than the current model's table.
+ def include_eager_order?(options, tables = nil)
+ ((tables || order_tables(options)) - [table_name]).any?
+ end
+
+ def include_eager_select?(options)
+ (selects_tables(options) - [table_name]).any?
+ end
+
+ def references_eager_loaded_tables?(options)
+ include_eager_order?(options) || include_eager_conditions?(options) || include_eager_select?(options)
+ 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
+ while (join = joins.shift).reflection.name.to_s != associations.to_s
+ raise ConfigurationError, "Not Enough Associations" if joins.empty?
+ end
+ 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|
+ association = construct_association(parent, joins.shift, row)
+ 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)
+ 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?
+ record.send("set_#{join.reflection.name}_target", association)
+ 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)
+ record.send("set_#{join.reflection.name}_target", association)
+ else
+ raise ConfigurationError, "unknown macro: #{join.reflection.macro}"
+ end
+ return association
+ 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,
+ 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]))} " 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+#{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
projects / depot.git / blobdiff