2 class HasManyThroughAssociationNotFoundError
< ActiveRecordError
#:nodoc:
3 def initialize(owner_class_name
, reflection
)
4 super("Could not find the association #{reflection.options[:through].inspect} in model #{owner_class_name}")
8 class HasManyThroughAssociationPolymorphicError
< ActiveRecordError
#:nodoc:
9 def initialize(owner_class_name
, reflection
, source_reflection
)
10 super("Cannot have a has_many :through association '#{owner_class_name}##{reflection.name}' on the polymorphic object '#{source_reflection.class_name}##{source_reflection.name}'.")
14 class HasManyThroughAssociationPointlessSourceTypeError
< ActiveRecordError
#:nodoc:
15 def initialize(owner_class_name
, reflection
, source_reflection
)
16 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.")
20 class HasManyThroughSourceAssociationNotFoundError
< ActiveRecordError
#:nodoc:
21 def initialize(reflection
)
22 through_reflection
= reflection
.through_reflection
23 source_reflection_names
= reflection
.source_reflection_names
24 source_associations
= reflection
.through_reflection
.klass
.reflect_on_all_associations
.collect
{ |a
| a
.name
.inspect
}
25 super("Could not find the source association(s) #{source_reflection_names.collect(&:inspect).to_sentence(:two_words_connector => ' or ', :last_word_connector => ', or ', :locale => :en)} in model #{through_reflection.klass}. Try 'has_many #{reflection.name.inspect}, :through => #{through_reflection.name.inspect}, :source => <name>'. Is it one of #{source_associations.to_sentence(:two_words_connector => ' or ', :last_word_connector => ', or ', :locale => :en)}?")
29 class HasManyThroughSourceAssociationMacroError
< ActiveRecordError
#:nodoc:
30 def initialize(reflection
)
31 through_reflection
= reflection
.through_reflection
32 source_reflection
= reflection
.source_reflection
33 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.")
37 class HasManyThroughCantAssociateThroughHasManyReflection
< ActiveRecordError
#:nodoc:
38 def initialize(owner
, reflection
)
39 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}.")
42 class HasManyThroughCantAssociateNewRecords
< ActiveRecordError
#:nodoc:
43 def initialize(owner
, reflection
)
44 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.")
48 class HasManyThroughCantDissociateNewRecords
< ActiveRecordError
#:nodoc:
49 def initialize(owner
, reflection
)
50 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.")
54 class HasAndBelongsToManyAssociationForeignKeyNeeded
< ActiveRecordError
#:nodoc:
55 def initialize(reflection
)
56 super("Cannot create self referential has_and_belongs_to_many association on '#{reflection.class_name rescue nil}##{reflection.name rescue nil}'. :association_foreign_key cannot be the same as the :foreign_key.")
60 class EagerLoadPolymorphicError
< ActiveRecordError
#:nodoc:
61 def initialize(reflection
)
62 super("Can not eagerly load the polymorphic association #{reflection.name.inspect}")
66 class ReadOnlyAssociation
< ActiveRecordError
#:nodoc:
67 def initialize(reflection
)
68 super("Can not add to a has_many :through association. Try adding to #{reflection.through_reflection.name.inspect}.")
72 # See ActiveRecord::Associations::ClassMethods for documentation.
73 module Associations
# :nodoc:
74 # These classes will be loaded when associations are created.
75 # So there is no need to eager load them.
76 autoload
:AssociationCollection, 'active_record/associations/association_collection'
77 autoload
:AssociationProxy, 'active_record/associations/association_proxy'
78 autoload
:BelongsToAssociation, 'active_record/associations/belongs_to_association'
79 autoload
:BelongsToPolymorphicAssociation, 'active_record/associations/belongs_to_polymorphic_association'
80 autoload
:HasAndBelongsToManyAssociation, 'active_record/associations/has_and_belongs_to_many_association'
81 autoload
:HasManyAssociation, 'active_record/associations/has_many_association'
82 autoload
:HasManyThroughAssociation, 'active_record/associations/has_many_through_association'
83 autoload
:HasOneAssociation, 'active_record/associations/has_one_association'
84 autoload
:HasOneThroughAssociation, 'active_record/associations/has_one_through_association'
86 def self.included(base
)
87 base
.extend(ClassMethods
)
90 # Clears out the association cache
91 def clear_association_cache
#:nodoc:
92 self.class.reflect_on_all_associations
.to_a
.each
do |assoc
|
93 instance_variable_set
"@#{assoc.name}", nil
94 end unless self.new_record
?
98 # Gets the specified association instance if it responds to :loaded?, nil otherwise.
99 def association_instance_get(name
)
100 association
= instance_variable_get("@#{name}")
101 association
if association
.respond_to
?(:loaded?)
104 # Set the specified association instance.
105 def association_instance_set(name
, association
)
106 instance_variable_set("@#{name}", association
)
109 # Associations are a set of macro-like class methods for tying objects together through foreign keys. They express relationships like
110 # "Project has one Project Manager" or "Project belongs to a Portfolio". Each macro adds a number of methods to the class which are
111 # 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>
114 # class Project < ActiveRecord::Base
115 # belongs_to :portfolio
116 # has_one :project_manager
117 # has_many :milestones
118 # has_and_belongs_to_many :categories
121 # The project class now has the following methods (and more) to ease the traversal and manipulation of its relationships:
122 # * <tt>Project#portfolio, Project#portfolio=(portfolio), Project#portfolio.nil?</tt>
123 # * <tt>Project#project_manager, Project#project_manager=(project_manager), Project#project_manager.nil?,</tt>
124 # * <tt>Project#milestones.empty?, Project#milestones.size, Project#milestones, Project#milestones<<(milestone),</tt>
125 # <tt>Project#milestones.delete(milestone), Project#milestones.find(milestone_id), Project#milestones.find(:all, options),</tt>
126 # <tt>Project#milestones.build, Project#milestones.create</tt>
127 # * <tt>Project#categories.empty?, Project#categories.size, Project#categories, Project#categories<<(category1),</tt>
128 # <tt>Project#categories.delete(category1)</tt>
130 # === A word of warning
132 # Don't create associations that have the same name as instance methods of ActiveRecord::Base. Since the association
133 # adds a method with that name to its model, it will override the inherited method and break things.
134 # For instance, +attributes+ and +connection+ would be bad choices for association names.
136 # == Auto-generated methods
138 # === Singular associations (one-to-one)
140 # generated methods | belongs_to | :polymorphic | has_one
141 # ----------------------------------+------------+--------------+---------
143 # other=(other) | X | X | X
144 # build_other(attributes={}) | X | | X
145 # create_other(attributes={}) | X | | X
146 # other.create!(attributes={}) | | | X
148 # ===Collection associations (one-to-many / many-to-many)
150 # generated methods | habtm | has_many | :through
151 # ----------------------------------+-------+----------+----------
153 # others=(other,other,...) | X | X | X
154 # other_ids | X | X | X
155 # other_ids=(id,id,...) | X | X | X
156 # others<< | X | X | X
157 # others.push | X | X | X
158 # others.concat | X | X | X
159 # others.build(attributes={}) | X | X | X
160 # others.create(attributes={}) | X | X | X
161 # others.create!(attributes={}) | X | X | X
162 # others.size | X | X | X
163 # others.length | X | X | X
164 # others.count | X | X | X
165 # others.sum(args*,&block) | X | X | X
166 # others.empty? | X | X | X
167 # others.clear | X | X | X
168 # others.delete(other,other,...) | X | X | X
169 # others.delete_all | X | X |
170 # others.destroy_all | X | X | X
171 # others.find(*args) | X | X | X
172 # others.find_first | X | |
173 # others.exists? | X | X | X
174 # others.uniq | X | X | X
175 # others.reset | X | X | X
177 # == Cardinality and associations
179 # Active Record associations can be used to describe one-to-one, one-to-many and many-to-many
180 # relationships between models. Each model uses an association to describe its role in
181 # the relation. The +belongs_to+ association is always used in the model that has
186 # Use +has_one+ in the base, and +belongs_to+ in the associated model.
188 # class Employee < ActiveRecord::Base
191 # class Office < ActiveRecord::Base
192 # belongs_to :employee # foreign key - employee_id
197 # Use +has_many+ in the base, and +belongs_to+ in the associated model.
199 # class Manager < ActiveRecord::Base
200 # has_many :employees
202 # class Employee < ActiveRecord::Base
203 # belongs_to :manager # foreign key - manager_id
208 # There are two ways to build a many-to-many relationship.
210 # The first way uses a +has_many+ association with the <tt>:through</tt> option and a join model, so
211 # there are two stages of associations.
213 # class Assignment < ActiveRecord::Base
214 # belongs_to :programmer # foreign key - programmer_id
215 # belongs_to :project # foreign key - project_id
217 # class Programmer < ActiveRecord::Base
218 # has_many :assignments
219 # has_many :projects, :through => :assignments
221 # class Project < ActiveRecord::Base
222 # has_many :assignments
223 # has_many :programmers, :through => :assignments
226 # For the second way, use +has_and_belongs_to_many+ in both models. This requires a join table
227 # that has no corresponding model or primary key.
229 # class Programmer < ActiveRecord::Base
230 # has_and_belongs_to_many :projects # foreign keys in the join table
232 # class Project < ActiveRecord::Base
233 # has_and_belongs_to_many :programmers # foreign keys in the join table
236 # Choosing which way to build a many-to-many relationship is not always simple.
237 # If you need to work with the relationship model as its own entity,
238 # use <tt>has_many :through</tt>. Use +has_and_belongs_to_many+ when working with legacy schemas or when
239 # you never work directly with the relationship itself.
241 # == Is it a +belongs_to+ or +has_one+ association?
243 # Both express a 1-1 relationship. The difference is mostly where to place the foreign key, which goes on the table for the class
244 # declaring the +belongs_to+ relationship. Example:
246 # class User < ActiveRecord::Base
247 # # I reference an account.
248 # belongs_to :account
251 # class Account < ActiveRecord::Base
252 # # One user references me.
256 # The tables for these classes could look something like:
258 # CREATE TABLE users (
259 # id int(11) NOT NULL auto_increment,
260 # account_id int(11) default NULL,
261 # name varchar default NULL,
265 # CREATE TABLE accounts (
266 # id int(11) NOT NULL auto_increment,
267 # name varchar default NULL,
271 # == Unsaved objects and associations
273 # You can manipulate objects and associations before they are saved to the database, but there is some special behavior you should be
274 # aware of, mostly involving the saving of associated objects.
276 # Unless you enable the :autosave option on a <tt>has_one</tt>, <tt>belongs_to</tt>,
277 # <tt>has_many</tt>, or <tt>has_and_belongs_to_many</tt> association,
278 # in which case the members are always saved.
280 # === One-to-one associations
282 # * Assigning an object to a +has_one+ association automatically saves that object and the object being replaced (if there is one), in
283 # order to update their primary keys - except if the parent object is unsaved (<tt>new_record? == true</tt>).
284 # * If either of these saves fail (due to one of the objects being invalid) the assignment statement returns +false+ and the assignment
286 # * If you wish to assign an object to a +has_one+ association without saving it, use the <tt>association.build</tt> method (documented below).
287 # * Assigning an object to a +belongs_to+ association does not save the object, since the foreign key field belongs on the parent. It
288 # does not save the parent either.
292 # * Adding an object to a collection (+has_many+ or +has_and_belongs_to_many+) automatically saves that object, except if the parent object
293 # (the owner of the collection) is not yet stored in the database.
294 # * If saving any of the objects being added to a collection (via <tt>push</tt> or similar) fails, then <tt>push</tt> returns +false+.
295 # * You can add an object to a collection without automatically saving it by using the <tt>collection.build</tt> method (documented below).
296 # * All unsaved (<tt>new_record? == true</tt>) members of the collection are automatically saved when the parent is saved.
298 # === Association callbacks
300 # Similar to the normal callbacks that hook into the lifecycle of an Active Record object, you can also define callbacks that get
301 # triggered when you add an object to or remove an object from an association collection. Example:
304 # has_and_belongs_to_many :developers, :after_add => :evaluate_velocity
306 # def evaluate_velocity(developer)
311 # It's possible to stack callbacks by passing them as an array. Example:
314 # has_and_belongs_to_many :developers, :after_add => [:evaluate_velocity, Proc.new { |p, d| p.shipping_date = Time.now}]
317 # Possible callbacks are: +before_add+, +after_add+, +before_remove+ and +after_remove+.
319 # Should any of the +before_add+ callbacks throw an exception, the object does not get added to the collection. Same with
320 # the +before_remove+ callbacks; if an exception is thrown the object doesn't get removed.
322 # === Association extensions
324 # The proxy objects that control the access to associations can be extended through anonymous modules. This is especially
325 # beneficial for adding new finders, creators, and other factory-type methods that are only used as part of this association.
328 # class Account < ActiveRecord::Base
329 # has_many :people do
330 # def find_or_create_by_name(name)
331 # first_name, last_name = name.split(" ", 2)
332 # find_or_create_by_first_name_and_last_name(first_name, last_name)
337 # person = Account.find(:first).people.find_or_create_by_name("David Heinemeier Hansson")
338 # person.first_name # => "David"
339 # person.last_name # => "Heinemeier Hansson"
341 # If you need to share the same extensions between many associations, you can use a named extension module. Example:
343 # module FindOrCreateByNameExtension
344 # def find_or_create_by_name(name)
345 # first_name, last_name = name.split(" ", 2)
346 # find_or_create_by_first_name_and_last_name(first_name, last_name)
350 # class Account < ActiveRecord::Base
351 # has_many :people, :extend => FindOrCreateByNameExtension
354 # class Company < ActiveRecord::Base
355 # has_many :people, :extend => FindOrCreateByNameExtension
358 # If you need to use multiple named extension modules, you can specify an array of modules with the <tt>:extend</tt> option.
359 # In the case of name conflicts between methods in the modules, methods in modules later in the array supercede
360 # those earlier in the array. Example:
362 # class Account < ActiveRecord::Base
363 # has_many :people, :extend => [FindOrCreateByNameExtension, FindRecentExtension]
366 # Some extensions can only be made to work with knowledge of the association proxy's internals.
367 # Extensions can access relevant state using accessors on the association proxy:
369 # * +proxy_owner+ - Returns the object the association is part of.
370 # * +proxy_reflection+ - Returns the reflection object that describes the association.
371 # * +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+.
373 # === Association Join Models
375 # Has Many associations can be configured with the <tt>:through</tt> option to use an explicit join model to retrieve the data. This
376 # operates similarly to a +has_and_belongs_to_many+ association. The advantage is that you're able to add validations,
377 # callbacks, and extra attributes on the join model. Consider the following schema:
379 # class Author < ActiveRecord::Base
380 # has_many :authorships
381 # has_many :books, :through => :authorships
384 # class Authorship < ActiveRecord::Base
389 # @author = Author.find :first
390 # @author.authorships.collect { |a| a.book } # selects all books that the author's authorships belong to.
391 # @author.books # selects all books by using the Authorship join model
393 # You can also go through a +has_many+ association on the join model:
395 # class Firm < ActiveRecord::Base
397 # has_many :invoices, :through => :clients
400 # class Client < ActiveRecord::Base
405 # class Invoice < ActiveRecord::Base
409 # @firm = Firm.find :first
410 # @firm.clients.collect { |c| c.invoices }.flatten # select all invoices for all clients of the firm
411 # @firm.invoices # selects all invoices by going through the Client join model.
413 # === Polymorphic Associations
415 # Polymorphic associations on models are not restricted on what types of models they can be associated with. Rather, they
416 # specify an interface that a +has_many+ association must adhere to.
418 # class Asset < ActiveRecord::Base
419 # belongs_to :attachable, :polymorphic => true
422 # class Post < ActiveRecord::Base
423 # has_many :assets, :as => :attachable # The :as option specifies the polymorphic interface to use.
426 # @asset.attachable = @post
428 # 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
429 # an +attachable_id+ integer column and an +attachable_type+ string column.
431 # Using polymorphic associations in combination with single table inheritance (STI) is a little tricky. In order
432 # for the associations to work as expected, ensure that you store the base model for the STI models in the
433 # type column of the polymorphic association. To continue with the asset example above, suppose there are guest posts
434 # and member posts that use the posts table for STI. In this case, there must be a +type+ column in the posts table.
436 # class Asset < ActiveRecord::Base
437 # belongs_to :attachable, :polymorphic => true
439 # def attachable_type=(sType)
440 # super(sType.to_s.classify.constantize.base_class.to_s)
444 # class Post < ActiveRecord::Base
445 # # because we store "Post" in attachable_type now :dependent => :destroy will work
446 # has_many :assets, :as => :attachable, :dependent => :destroy
449 # class GuestPost < Post
452 # class MemberPost < Post
457 # All of the methods are built on a simple caching principle that will keep the result of the last query around unless specifically
458 # instructed not to. The cache is even shared across methods to make it even cheaper to use the macro-added methods without
459 # worrying too much about performance at the first go. Example:
461 # project.milestones # fetches milestones from the database
462 # project.milestones.size # uses the milestone cache
463 # project.milestones.empty? # uses the milestone cache
464 # project.milestones(true).size # fetches milestones from the database
465 # project.milestones # uses the milestone cache
467 # == Eager loading of associations
469 # Eager loading is a way to find objects of a certain class and a number of named associations. This is
470 # 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
471 # triggers 101 database queries. Through the use of eager loading, the 101 queries can be reduced to 2. Example:
473 # class Post < ActiveRecord::Base
478 # Consider the following loop using the class above:
480 # for post in Post.all
481 # puts "Post: " + post.title
482 # puts "Written by: " + post.author.name
483 # puts "Last comment on: " + post.comments.first.created_on
486 # To iterate over these one hundred posts, we'll generate 201 database queries. Let's first just optimize it for retrieving the author:
488 # for post in Post.find(:all, :include => :author)
490 # This references the name of the +belongs_to+ association that also used the <tt>:author</tt> symbol. After loading the posts, find
491 # 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.
493 # We can improve upon the situation further by referencing both associations in the finder with:
495 # for post in Post.find(:all, :include => [ :author, :comments ])
497 # This will load all comments with a single query. This reduces the total number of queries to 3. More generally the number of queries
498 # will be 1 plus the number of associations named (except if some of the associations are polymorphic +belongs_to+ - see below).
500 # To include a deep hierarchy of associations, use a hash:
502 # for post in Post.find(:all, :include => [ :author, { :comments => { :author => :gravatar } } ])
504 # That'll grab not only all the comments but all their authors and gravatar pictures. You can mix and match
505 # symbols, arrays and hashes in any combination to describe the associations you want to load.
507 # 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
508 # 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
509 # 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.
511 # 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
512 # Active Record falls back to the previously used LEFT OUTER JOIN based strategy. For example
514 # Post.find(:all, :include => [ :author, :comments ], :conditions => ['comments.approved = ?', true])
516 # 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
517 # <tt>LEFT OUTER JOIN authors ON authors.id = posts.author_id</tt>. Note that using conditions like this can have unintended consequences.
518 # 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
519 # and not just to the association. You must disambiguate column references for this fallback to happen, for example
520 # <tt>:order => "author.name DESC"</tt> will work but <tt>:order => "name DESC"</tt> will not.
522 # If you do want eagerload only some members of an association it is usually more natural to <tt>:include</tt> an association
523 # which has conditions defined on it:
525 # class Post < ActiveRecord::Base
526 # has_many :approved_comments, :class_name => 'Comment', :conditions => ['approved = ?', true]
529 # Post.find(:all, :include => :approved_comments)
531 # will load posts and eager load the +approved_comments+ association, which contains only those comments that have been approved.
533 # If you eager load an association with a specified <tt>:limit</tt> option, it will be ignored, returning all the associated objects:
535 # class Picture < ActiveRecord::Base
536 # has_many :most_recent_comments, :class_name => 'Comment', :order => 'id DESC', :limit => 10
539 # Picture.find(:first, :include => :most_recent_comments).most_recent_comments # => returns all associated comments.
541 # When eager loaded, conditions are interpolated in the context of the model class, not the model instance. Conditions are lazily interpolated
542 # before the actual model exists.
544 # Eager loading is supported with polymorphic associations.
546 # class Address < ActiveRecord::Base
547 # belongs_to :addressable, :polymorphic => true
550 # A call that tries to eager load the addressable model
552 # Address.find(:all, :include => :addressable)
554 # will execute one query to load the addresses and load the addressables with one query per addressable type.
555 # 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
556 # addressable types to load is determined on the back of the addresses loaded. This is not supported if Active Record has to fallback
557 # to the previous implementation of eager loading and will raise ActiveRecord::EagerLoadPolymorphicError. The reason is that the parent
558 # model's type is a column value so its corresponding table name cannot be put in the +FROM+/+JOIN+ clauses of that query.
562 # 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,
563 # the standard table name is used. The second time, the table is aliased as <tt>#{reflection_name}_#{parent_table_name}</tt>. Indexes are appended
564 # for any more successive uses of the table name.
566 # Post.find :all, :joins => :comments
567 # # => SELECT ... FROM posts INNER JOIN comments ON ...
568 # Post.find :all, :joins => :special_comments # STI
569 # # => SELECT ... FROM posts INNER JOIN comments ON ... AND comments.type = 'SpecialComment'
570 # Post.find :all, :joins => [:comments, :special_comments] # special_comments is the reflection name, posts is the parent table name
571 # # => SELECT ... FROM posts INNER JOIN comments ON ... INNER JOIN comments special_comments_posts
573 # Acts as tree example:
575 # TreeMixin.find :all, :joins => :children
576 # # => SELECT ... FROM mixins INNER JOIN mixins childrens_mixins ...
577 # TreeMixin.find :all, :joins => {:children => :parent}
578 # # => SELECT ... FROM mixins INNER JOIN mixins childrens_mixins ...
579 # INNER JOIN parents_mixins ...
580 # TreeMixin.find :all, :joins => {:children => {:parent => :children}}
581 # # => SELECT ... FROM mixins INNER JOIN mixins childrens_mixins ...
582 # INNER JOIN parents_mixins ...
583 # INNER JOIN mixins childrens_mixins_2
585 # Has and Belongs to Many join tables use the same idea, but add a <tt>_join</tt> suffix:
587 # Post.find :all, :joins => :categories
588 # # => SELECT ... FROM posts INNER JOIN categories_posts ... INNER JOIN categories ...
589 # Post.find :all, :joins => {:categories => :posts}
590 # # => SELECT ... FROM posts INNER JOIN categories_posts ... INNER JOIN categories ...
591 # INNER JOIN categories_posts posts_categories_join INNER JOIN posts posts_categories
592 # Post.find :all, :joins => {:categories => {:posts => :categories}}
593 # # => SELECT ... FROM posts INNER JOIN categories_posts ... INNER JOIN categories ...
594 # INNER JOIN categories_posts posts_categories_join INNER JOIN posts posts_categories
595 # INNER JOIN categories_posts categories_posts_join INNER JOIN categories categories_posts_2
597 # 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:
599 # Post.find :all, :joins => :comments, :joins => "inner join comments ..."
600 # # => SELECT ... FROM posts INNER JOIN comments_posts ON ... INNER JOIN comments ...
601 # Post.find :all, :joins => [:comments, :special_comments], :joins => "inner join comments ..."
602 # # => SELECT ... FROM posts INNER JOIN comments comments_posts ON ...
603 # INNER JOIN comments special_comments_posts ...
604 # INNER JOIN comments ...
606 # Table aliases are automatically truncated according to the maximum length of table identifiers according to the specific database.
610 # By default, associations will look for objects within the current module scope. Consider:
612 # module MyApplication
614 # class Firm < ActiveRecord::Base
618 # class Client < ActiveRecord::Base; end
622 # When <tt>Firm#clients</tt> is called, it will in turn call <tt>MyApplication::Business::Client.find_all_by_firm_id(firm.id)</tt>.
623 # If you want to associate with a class in another module scope, this can be done by specifying the complete class name.
626 # module MyApplication
628 # class Firm < ActiveRecord::Base; end
632 # class Account < ActiveRecord::Base
633 # belongs_to :firm, :class_name => "MyApplication::Business::Firm"
638 # == Type safety with <tt>ActiveRecord::AssociationTypeMismatch</tt>
640 # If you attempt to assign an object to an association that doesn't match the inferred or specified <tt>:class_name</tt>, you'll
641 # get an <tt>ActiveRecord::AssociationTypeMismatch</tt>.
645 # All of the association macros can be specialized through options. This makes cases more complex than the simple and guessable ones
648 # Specifies a one-to-many association. The following methods for retrieval and query of
649 # collections of associated objects will be added:
651 # [collection(force_reload = false)]
652 # Returns an array of all the associated objects.
653 # An empty array is returned if none are found.
654 # [collection<<(object, ...)]
655 # Adds one or more objects to the collection by setting their foreign keys to the collection's primary key.
656 # [collection.delete(object, ...)]
657 # Removes one or more objects from the collection by setting their foreign keys to +NULL+.
658 # Objects will be in addition destroyed if they're associated with <tt>:dependent => :destroy</tt>,
659 # and deleted if they're associated with <tt>:dependent => :delete_all</tt>.
660 # [collection=objects]
661 # Replaces the collections content by deleting and adding objects as appropriate.
662 # [collection_singular_ids]
663 # Returns an array of the associated objects' ids
664 # [collection_singular_ids=ids]
665 # Replace the collection with the objects identified by the primary keys in +ids+
667 # Removes every object from the collection. This destroys the associated objects if they
668 # are associated with <tt>:dependent => :destroy</tt>, deletes them directly from the
669 # database if <tt>:dependent => :delete_all</tt>, otherwise sets their foreign keys to +NULL+.
670 # [collection.empty?]
671 # Returns +true+ if there are no associated objects.
673 # Returns the number of associated objects.
674 # [collection.find(...)]
675 # Finds an associated object according to the same rules as ActiveRecord::Base.find.
676 # [collection.exists?(...)]
677 # Checks whether an associated object with the given conditions exists.
678 # Uses the same rules as ActiveRecord::Base.exists?.
679 # [collection.build(attributes = {}, ...)]
680 # Returns one or more new objects of the collection type that have been instantiated
681 # with +attributes+ and linked to this object through a foreign key, but have not yet
682 # been saved. <b>Note:</b> This only works if an associated object already exists, not if
684 # [collection.create(attributes = {})]
685 # Returns a new object of the collection type that has been instantiated
686 # with +attributes+, linked to this object through a foreign key, and that has already
687 # been saved (if it passed the validation). <b>Note:</b> This only works if an associated
688 # object already exists, not if it's +nil+!
690 # (*Note*: +collection+ is replaced with the symbol passed as the first argument, so
691 # <tt>has_many :clients</tt> would add among others <tt>clients.empty?</tt>.)
695 # Example: A Firm class declares <tt>has_many :clients</tt>, which will add:
696 # * <tt>Firm#clients</tt> (similar to <tt>Clients.find :all, :conditions => ["firm_id = ?", id]</tt>)
697 # * <tt>Firm#clients<<</tt>
698 # * <tt>Firm#clients.delete</tt>
699 # * <tt>Firm#clients=</tt>
700 # * <tt>Firm#client_ids</tt>
701 # * <tt>Firm#client_ids=</tt>
702 # * <tt>Firm#clients.clear</tt>
703 # * <tt>Firm#clients.empty?</tt> (similar to <tt>firm.clients.size == 0</tt>)
704 # * <tt>Firm#clients.size</tt> (similar to <tt>Client.count "firm_id = #{id}"</tt>)
705 # * <tt>Firm#clients.find</tt> (similar to <tt>Client.find(id, :conditions => "firm_id = #{id}")</tt>)
706 # * <tt>Firm#clients.exists?(:name => 'ACME')</tt> (similar to <tt>Client.exists?(:name => 'ACME', :firm_id => firm.id)</tt>)
707 # * <tt>Firm#clients.build</tt> (similar to <tt>Client.new("firm_id" => id)</tt>)
708 # * <tt>Firm#clients.create</tt> (similar to <tt>c = Client.new("firm_id" => id); c.save; c</tt>)
709 # The declaration can also include an options hash to specialize the behavior of the association.
711 # === Supported options
713 # Specify the class name of the association. Use it only if that name can't be inferred
714 # from the association name. So <tt>has_many :products</tt> will by default be linked to the Product class, but
715 # if the real class name is SpecialProduct, you'll have to specify it with this option.
717 # Specify the conditions that the associated objects must meet in order to be included as a +WHERE+
718 # SQL fragment, such as <tt>price > 5 AND name LIKE 'B%'</tt>. Record creations from the association are scoped if a hash
719 # is used. <tt>has_many :posts, :conditions => {:published => true}</tt> will create published posts with <tt>@blog.posts.create</tt>
720 # or <tt>@blog.posts.build</tt>.
722 # Specify the order in which the associated objects are returned as an <tt>ORDER BY</tt> SQL fragment,
723 # such as <tt>last_name, first_name DESC</tt>.
725 # Specify the foreign key used for the association. By default this is guessed to be the name
726 # of this class in lower-case and "_id" suffixed. So a Person class that makes a +has_many+ association will use "person_id"
727 # as the default <tt>:foreign_key</tt>.
729 # Specify the method that returns the primary key used for the association. By default this is +id+.
731 # If set to <tt>:destroy</tt> all the associated objects are destroyed
732 # alongside this object by calling their +destroy+ method. If set to <tt>:delete_all</tt> all associated
733 # objects are deleted *without* calling their +destroy+ method. If set to <tt>:nullify</tt> all associated
734 # objects' foreign keys are set to +NULL+ *without* calling their +save+ callbacks. *Warning:* This option is ignored when also using
735 # the <tt>:through</tt> option.
737 # Specify a complete SQL statement to fetch the association. This is a good way to go for complex
738 # associations that depend on multiple tables. Note: When this option is used, +find_in_collection+ is _not_ added.
740 # Specify a complete SQL statement to fetch the size of the association. If <tt>:finder_sql</tt> is
741 # 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>.
743 # Specify a named module for extending the proxy. See "Association extensions".
745 # Specify second-order associations that should be eager loaded when the collection is loaded.
747 # An attribute name by which the result should be grouped. Uses the <tt>GROUP BY</tt> SQL-clause.
749 # Combined with +:group+ this can be used to filter the records that a <tt>GROUP BY</tt> returns. Uses the <tt>HAVING</tt> SQL-clause.
751 # An integer determining the limit on the number of rows that should be returned.
753 # An integer determining the offset from where the rows should be fetched. So at 5, it would skip the first 4 rows.
755 # 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
756 # but not include the joined columns. Do not forget to include the primary and foreign keys, otherwise it will raise an error.
758 # Specifies a polymorphic interface (See <tt>belongs_to</tt>).
760 # Specifies a Join Model through which to perform the query. Options for <tt>:class_name</tt> and <tt>:foreign_key</tt>
761 # are ignored, as the association uses the source reflection. You can only use a <tt>:through</tt> query through a <tt>belongs_to</tt>
762 # or <tt>has_many</tt> association on the join model.
764 # Specifies the source association name used by <tt>has_many :through</tt> queries. Only use it if the name cannot be
765 # inferred from the association. <tt>has_many :subscribers, :through => :subscriptions</tt> will look for either <tt>:subscribers</tt> or
766 # <tt>:subscriber</tt> on Subscription, unless a <tt>:source</tt> is given.
768 # Specifies type of the source association used by <tt>has_many :through</tt> queries where the source
769 # association is a polymorphic +belongs_to+.
771 # If true, duplicates will be omitted from the collection. Useful in conjunction with <tt>:through</tt>.
773 # If true, all the associated objects are readonly through the association.
775 # If false, don't validate the associated objects when saving the parent object. true by default.
777 # If true, always save any loaded members and destroy members marked for destruction, when saving the parent object. Off by default.
780 # has_many :comments, :order => "posted_on"
781 # has_many :comments, :include => :author
782 # has_many :people, :class_name => "Person", :conditions => "deleted = 0", :order => "name"
783 # has_many :tracks, :order => "position", :dependent => :destroy
784 # has_many :comments, :dependent => :nullify
785 # has_many :tags, :as => :taggable
786 # has_many :reports, :readonly => true
787 # has_many :subscribers, :through => :subscriptions, :source => :user
788 # has_many :subscribers, :class_name => "Person", :finder_sql =>
789 # 'SELECT DISTINCT people.* ' +
790 # 'FROM people p, post_subscriptions ps ' +
791 # 'WHERE ps.post_id = #{id} AND ps.person_id = p.id ' +
792 # 'ORDER BY p.first_name'
793 def has_many(association_id
, options
= {}, &extension
)
794 reflection
= create_has_many_reflection(association_id
, options
, &extension
)
795 configure_dependency_for_has_many(reflection
)
796 add_association_callbacks(reflection
.name
, reflection
.options
)
799 collection_accessor_methods(reflection
, HasManyThroughAssociation
)
801 collection_accessor_methods(reflection
, HasManyAssociation
)
805 # Specifies a one-to-one association with another class. This method should only be used
806 # if the other class contains the foreign key. If the current class contains the foreign key,
807 # then you should use +belongs_to+ instead. See also ActiveRecord::Associations::ClassMethods's overview
808 # on when to use has_one and when to use belongs_to.
810 # The following methods for retrieval and query of a single associated object will be added:
812 # [association(force_reload = false)]
813 # Returns the associated object. +nil+ is returned if none is found.
814 # [association=(associate)]
815 # Assigns the associate object, extracts the primary key, sets it as the foreign key,
816 # and saves the associate object.
817 # [build_association(attributes = {})]
818 # Returns a new object of the associated type that has been instantiated
819 # with +attributes+ and linked to this object through a foreign key, but has not
820 # yet been saved. <b>Note:</b> This ONLY works if an association already exists.
821 # It will NOT work if the association is +nil+.
822 # [create_association(attributes = {})]
823 # Returns a new object of the associated type that has been instantiated
824 # with +attributes+, linked to this object through a foreign key, and that
825 # has already been saved (if it passed the validation).
827 # (+association+ is replaced with the symbol passed as the first argument, so
828 # <tt>has_one :manager</tt> would add among others <tt>manager.nil?</tt>.)
832 # An Account class declares <tt>has_one :beneficiary</tt>, which will add:
833 # * <tt>Account#beneficiary</tt> (similar to <tt>Beneficiary.find(:first, :conditions => "account_id = #{id}")</tt>)
834 # * <tt>Account#beneficiary=(beneficiary)</tt> (similar to <tt>beneficiary.account_id = account.id; beneficiary.save</tt>)
835 # * <tt>Account#build_beneficiary</tt> (similar to <tt>Beneficiary.new("account_id" => id)</tt>)
836 # * <tt>Account#create_beneficiary</tt> (similar to <tt>b = Beneficiary.new("account_id" => id); b.save; b</tt>)
840 # The declaration can also include an options hash to specialize the behavior of the association.
844 # Specify the class name of the association. Use it only if that name can't be inferred
845 # from the association name. So <tt>has_one :manager</tt> will by default be linked to the Manager class, but
846 # if the real class name is Person, you'll have to specify it with this option.
848 # Specify the conditions that the associated object must meet in order to be included as a +WHERE+
849 # SQL fragment, such as <tt>rank = 5</tt>.
851 # Specify the order in which the associated objects are returned as an <tt>ORDER BY</tt> SQL fragment,
852 # such as <tt>last_name, first_name DESC</tt>.
854 # If set to <tt>:destroy</tt>, the associated object is destroyed when this object is. If set to
855 # <tt>:delete</tt>, the associated object is deleted *without* calling its destroy method. If set to <tt>:nullify</tt>, the associated
856 # object's foreign key is set to +NULL+. Also, association is assigned.
858 # Specify the foreign key used for the association. By default this is guessed to be the name
859 # of this class in lower-case and "_id" suffixed. So a Person class that makes a +has_one+ association will use "person_id"
860 # as the default <tt>:foreign_key</tt>.
862 # Specify the method that returns the primary key used for the association. By default this is +id+.
864 # Specify second-order associations that should be eager loaded when this object is loaded.
866 # Specifies a polymorphic interface (See <tt>belongs_to</tt>).
868 # 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
869 # but not include the joined columns. Do not forget to include the primary and foreign keys, otherwise it will raise an error.
871 # Specifies a Join Model through which to perform the query. Options for <tt>:class_name</tt> and <tt>:foreign_key</tt>
872 # are ignored, as the association uses the source reflection. You can only use a <tt>:through</tt> query through a
873 # <tt>has_one</tt> or <tt>belongs_to</tt> association on the join model.
875 # Specifies the source association name used by <tt>has_one :through</tt> queries. Only use it if the name cannot be
876 # inferred from the association. <tt>has_one :favorite, :through => :favorites</tt> will look for a
877 # <tt>:favorite</tt> on Favorite, unless a <tt>:source</tt> is given.
879 # Specifies type of the source association used by <tt>has_one :through</tt> queries where the source
880 # association is a polymorphic +belongs_to+.
882 # If true, the associated object is readonly through the association.
884 # If false, don't validate the associated object when saving the parent object. +false+ by default.
886 # If true, always save the associated object or destroy it if marked for destruction, when saving the parent object. Off by default.
889 # has_one :credit_card, :dependent => :destroy # destroys the associated credit card
890 # has_one :credit_card, :dependent => :nullify # updates the associated records foreign key value to NULL rather than destroying it
891 # has_one :last_comment, :class_name => "Comment", :order => "posted_on"
892 # has_one :project_manager, :class_name => "Person", :conditions => "role = 'project_manager'"
893 # has_one :attachment, :as => :attachable
894 # has_one :boss, :readonly => :true
895 # has_one :club, :through => :membership
896 # has_one :primary_address, :through => :addressables, :conditions => ["addressable.primary = ?", true], :source => :addressable
897 def has_one(association_id
, options
= {})
899 reflection
= create_has_one_through_reflection(association_id
, options
)
900 association_accessor_methods(reflection
, ActiveRecord
::Associations::HasOneThroughAssociation)
902 reflection
= create_has_one_reflection(association_id
, options
)
903 association_accessor_methods(reflection
, HasOneAssociation
)
904 association_constructor_method(:build, reflection
, HasOneAssociation
)
905 association_constructor_method(:create, reflection
, HasOneAssociation
)
906 configure_dependency_for_has_one(reflection
)
910 # Specifies a one-to-one association with another class. This method should only be used
911 # if this class contains the foreign key. If the other class contains the foreign key,
912 # then you should use +has_one+ instead. See also ActiveRecord::Associations::ClassMethods's overview
913 # on when to use +has_one+ and when to use +belongs_to+.
915 # Methods will be added for retrieval and query for a single associated object, for which
916 # this object holds an id:
918 # [association(force_reload = false)]
919 # Returns the associated object. +nil+ is returned if none is found.
920 # [association=(associate)]
921 # Assigns the associate object, extracts the primary key, and sets it as the foreign key.
922 # [build_association(attributes = {})]
923 # Returns a new object of the associated type that has been instantiated
924 # with +attributes+ and linked to this object through a foreign key, but has not yet been saved.
925 # [create_association(attributes = {})]
926 # Returns a new object of the associated type that has been instantiated
927 # with +attributes+, linked to this object through a foreign key, and that
928 # has already been saved (if it passed the validation).
930 # (+association+ is replaced with the symbol passed as the first argument, so
931 # <tt>belongs_to :author</tt> would add among others <tt>author.nil?</tt>.)
935 # A Post class declares <tt>belongs_to :author</tt>, which will add:
936 # * <tt>Post#author</tt> (similar to <tt>Author.find(author_id)</tt>)
937 # * <tt>Post#author=(author)</tt> (similar to <tt>post.author_id = author.id</tt>)
938 # * <tt>Post#author?</tt> (similar to <tt>post.author == some_author</tt>)
939 # * <tt>Post#build_author</tt> (similar to <tt>post.author = Author.new</tt>)
940 # * <tt>Post#create_author</tt> (similar to <tt>post.author = Author.new; post.author.save; post.author</tt>)
941 # The declaration can also include an options hash to specialize the behavior of the association.
946 # Specify the class name of the association. Use it only if that name can't be inferred
947 # from the association name. So <tt>has_one :author</tt> will by default be linked to the Author class, but
948 # if the real class name is Person, you'll have to specify it with this option.
950 # Specify the conditions that the associated object must meet in order to be included as a +WHERE+
951 # SQL fragment, such as <tt>authorized = 1</tt>.
953 # 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
954 # but not include the joined columns. Do not forget to include the primary and foreign keys, otherwise it will raise an error.
956 # Specify the foreign key used for the association. By default this is guessed to be the name
957 # of the association with an "_id" suffix. So a class that defines a <tt>belongs_to :person</tt> association will use
958 # "person_id" as the default <tt>:foreign_key</tt>. Similarly, <tt>belongs_to :favorite_person, :class_name => "Person"</tt>
959 # will use a foreign key of "favorite_person_id".
961 # If set to <tt>:destroy</tt>, the associated object is destroyed when this object is. If set to
962 # <tt>:delete</tt>, the associated object is deleted *without* calling its destroy method. This option should not be specified when
963 # <tt>belongs_to</tt> is used in conjunction with a <tt>has_many</tt> relationship on another class because of the potential to leave
964 # orphaned records behind.
966 # Caches the number of belonging objects on the associate class through the use of +increment_counter+
967 # and +decrement_counter+. The counter cache is incremented when an object of this class is created and decremented when it's
968 # destroyed. This requires that a column named <tt>#{table_name}_count</tt> (such as +comments_count+ for a belonging Comment class)
969 # is used on the associate class (such as a Post class). You can also specify a custom counter cache column by providing
970 # a column name instead of a +true+/+false+ value to this option (e.g., <tt>:counter_cache => :my_custom_counter</tt>.)
971 # Note: Specifying a counter cache will add it to that model's list of readonly attributes using +attr_readonly+.
973 # Specify second-order associations that should be eager loaded when this object is loaded.
975 # Specify this association is a polymorphic association by passing +true+.
976 # Note: If you've enabled the counter cache, then you may want to add the counter cache attribute
977 # to the +attr_readonly+ list in the associated classes (e.g. <tt>class Post; attr_readonly :comments_count; end</tt>).
979 # If true, the associated object is readonly through the association.
981 # If false, don't validate the associated objects when saving the parent object. +false+ by default.
983 # If true, always save the associated object or destroy it if marked for destruction, when saving the parent object. Off by default.
986 # belongs_to :firm, :foreign_key => "client_of"
987 # belongs_to :author, :class_name => "Person", :foreign_key => "author_id"
988 # belongs_to :valid_coupon, :class_name => "Coupon", :foreign_key => "coupon_id",
989 # :conditions => 'discounts > #{payments_count}'
990 # belongs_to :attachable, :polymorphic => true
991 # belongs_to :project, :readonly => true
992 # belongs_to :post, :counter_cache => true
993 def belongs_to(association_id
, options
= {})
994 reflection
= create_belongs_to_reflection(association_id
, options
)
996 if reflection
.options
[:polymorphic]
997 association_accessor_methods(reflection
, BelongsToPolymorphicAssociation
)
999 association_accessor_methods(reflection
, BelongsToAssociation
)
1000 association_constructor_method(:build, reflection
, BelongsToAssociation
)
1001 association_constructor_method(:create, reflection
, BelongsToAssociation
)
1004 # Create the callbacks to update counter cache
1005 if options
[:counter_cache]
1006 cache_column
= reflection
.counter_cache_column
1008 method_name
= "belongs_to_counter_cache_after_create_for_#{reflection.name}".to_sym
1009 define_method(method_name
) do
1010 association
= send(reflection
.name
)
1011 association
.class.increment_counter(cache_column
, send(reflection
.primary_key_name
)) unless association
.nil?
1013 after_create method_name
1015 method_name
= "belongs_to_counter_cache_before_destroy_for_#{reflection.name}".to_sym
1016 define_method(method_name
) do
1017 association
= send(reflection
.name
)
1018 association
.class.decrement_counter(cache_column
, send(reflection
.primary_key_name
)) unless association
.nil?
1020 before_destroy method_name
1023 "#{reflection.class_name}.send(:attr_readonly,\"#{cache_column}\".intern) if defined?(#{reflection.class_name}) && #{reflection.class_name}.respond_to?(:attr_readonly)"
1027 configure_dependency_for_belongs_to(reflection
)
1030 # Specifies a many-to-many relationship with another class. This associates two classes via an
1031 # intermediate join table. Unless the join table is explicitly specified as an option, it is
1032 # guessed using the lexical order of the class names. So a join between Developer and Project
1033 # will give the default join table name of "developers_projects" because "D" outranks "P". Note that this precedence
1034 # is calculated using the <tt><</tt> operator for String. This means that if the strings are of different lengths,
1035 # and the strings are equal when compared up to the shortest length, then the longer string is considered of higher
1036 # lexical precedence than the shorter one. For example, one would expect the tables "paper_boxes" and "papers"
1037 # to generate a join table name of "papers_paper_boxes" because of the length of the name "paper_boxes",
1038 # but it in fact generates a join table name of "paper_boxes_papers". Be aware of this caveat, and use the
1039 # custom <tt>:join_table</tt> option if you need to.
1041 # The join table should not have a primary key or a model associated with it. You must manually generate the
1042 # join table with a migration such as this:
1044 # class CreateDevelopersProjectsJoinTable < ActiveRecord::Migration
1046 # create_table :developers_projects, :id => false do |t|
1047 # t.integer :developer_id
1048 # t.integer :project_id
1053 # drop_table :developers_projects
1057 # Deprecated: Any additional fields added to the join table will be placed as attributes when pulling records out through
1058 # +has_and_belongs_to_many+ associations. Records returned from join tables with additional attributes will be marked as
1059 # readonly (because we can't save changes to the additional attributes). It's strongly recommended that you upgrade any
1060 # associations with attributes to a real join model (see introduction).
1062 # Adds the following methods for retrieval and query:
1064 # [collection(force_reload = false)]
1065 # Returns an array of all the associated objects.
1066 # An empty array is returned if none are found.
1067 # [collection<<(object, ...)]
1068 # Adds one or more objects to the collection by creating associations in the join table
1069 # (<tt>collection.push</tt> and <tt>collection.concat</tt> are aliases to this method).
1070 # [collection.delete(object, ...)]
1071 # Removes one or more objects from the collection by removing their associations from the join table.
1072 # This does not destroy the objects.
1073 # [collection=objects]
1074 # Replaces the collection's content by deleting and adding objects as appropriate.
1075 # [collection_singular_ids]
1076 # Returns an array of the associated objects' ids.
1077 # [collection_singular_ids=ids]
1078 # Replace the collection by the objects identified by the primary keys in +ids+.
1079 # [collection.clear]
1080 # Removes every object from the collection. This does not destroy the objects.
1081 # [collection.empty?]
1082 # Returns +true+ if there are no associated objects.
1084 # Returns the number of associated objects.
1085 # [collection.find(id)]
1086 # Finds an associated object responding to the +id+ and that
1087 # meets the condition that it has to be associated with this object.
1088 # Uses the same rules as ActiveRecord::Base.find.
1089 # [collection.exists?(...)]
1090 # Checks whether an associated object with the given conditions exists.
1091 # Uses the same rules as ActiveRecord::Base.exists?.
1092 # [collection.build(attributes = {})]
1093 # Returns a new object of the collection type that has been instantiated
1094 # with +attributes+ and linked to this object through the join table, but has not yet been saved.
1095 # [collection.create(attributes = {})]
1096 # Returns a new object of the collection type that has been instantiated
1097 # with +attributes+, linked to this object through the join table, and that has already been saved (if it passed the validation).
1099 # (+collection+ is replaced with the symbol passed as the first argument, so
1100 # <tt>has_and_belongs_to_many :categories</tt> would add among others <tt>categories.empty?</tt>.)
1104 # A Developer class declares <tt>has_and_belongs_to_many :projects</tt>, which will add:
1105 # * <tt>Developer#projects</tt>
1106 # * <tt>Developer#projects<<</tt>
1107 # * <tt>Developer#projects.delete</tt>
1108 # * <tt>Developer#projects=</tt>
1109 # * <tt>Developer#project_ids</tt>
1110 # * <tt>Developer#project_ids=</tt>
1111 # * <tt>Developer#projects.clear</tt>
1112 # * <tt>Developer#projects.empty?</tt>
1113 # * <tt>Developer#projects.size</tt>
1114 # * <tt>Developer#projects.find(id)</tt>
1115 # * <tt>Developer#clients.exists?(...)</tt>
1116 # * <tt>Developer#projects.build</tt> (similar to <tt>Project.new("project_id" => id)</tt>)
1117 # * <tt>Developer#projects.create</tt> (similar to <tt>c = Project.new("project_id" => id); c.save; c</tt>)
1118 # The declaration may include an options hash to specialize the behavior of the association.
1123 # Specify the class name of the association. Use it only if that name can't be inferred
1124 # from the association name. So <tt>has_and_belongs_to_many :projects</tt> will by default be linked to the
1125 # Project class, but if the real class name is SuperProject, you'll have to specify it with this option.
1127 # Specify the name of the join table if the default based on lexical order isn't what you want.
1128 # <b>WARNING:</b> If you're overwriting the table name of either class, the +table_name+ method
1129 # MUST be declared underneath any +has_and_belongs_to_many+ declaration in order to work.
1131 # Specify the foreign key used for the association. By default this is guessed to be the name
1132 # of this class in lower-case and "_id" suffixed. So a Person class that makes a +has_and_belongs_to_many+ association
1133 # to Project will use "person_id" as the default <tt>:foreign_key</tt>.
1134 # [:association_foreign_key]
1135 # Specify the foreign key used for the association on the receiving side of the association.
1136 # By default this is guessed to be the name of the associated class in lower-case and "_id" suffixed.
1137 # So if a Person class makes a +has_and_belongs_to_many+ association to Project,
1138 # the association will use "project_id" as the default <tt>:association_foreign_key</tt>.
1140 # Specify the conditions that the associated object must meet in order to be included as a +WHERE+
1141 # SQL fragment, such as <tt>authorized = 1</tt>. Record creations from the association are scoped if a hash is used.
1142 # <tt>has_many :posts, :conditions => {:published => true}</tt> will create published posts with <tt>@blog.posts.create</tt>
1143 # or <tt>@blog.posts.build</tt>.
1145 # Specify the order in which the associated objects are returned as an <tt>ORDER BY</tt> SQL fragment,
1146 # such as <tt>last_name, first_name DESC</tt>
1148 # If true, duplicate associated objects will be ignored by accessors and query methods.
1150 # Overwrite the default generated SQL statement used to fetch the association with a manual statement
1152 # Specify a complete SQL statement to fetch the size of the association. If <tt>:finder_sql</tt> is
1153 # 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>.
1155 # Overwrite the default generated SQL statement used to remove links between the associated
1156 # classes with a manual statement.
1158 # Overwrite the default generated SQL statement used to add links between the associated classes
1159 # with a manual statement.
1161 # Anonymous module for extending the proxy, see "Association extensions".
1163 # Specify second-order associations that should be eager loaded when the collection is loaded.
1165 # An attribute name by which the result should be grouped. Uses the <tt>GROUP BY</tt> SQL-clause.
1167 # Combined with +:group+ this can be used to filter the records that a <tt>GROUP BY</tt> returns. Uses the <tt>HAVING</tt> SQL-clause.
1169 # An integer determining the limit on the number of rows that should be returned.
1171 # An integer determining the offset from where the rows should be fetched. So at 5, it would skip the first 4 rows.
1173 # 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
1174 # but not include the joined columns. Do not forget to include the primary and foreign keys, otherwise it will raise an error.
1176 # If true, all the associated objects are readonly through the association.
1178 # If false, don't validate the associated objects when saving the parent object. +true+ by default.
1180 # If true, always save any loaded members and destroy members marked for destruction, when saving the parent object. Off by default.
1183 # has_and_belongs_to_many :projects
1184 # has_and_belongs_to_many :projects, :include => [ :milestones, :manager ]
1185 # has_and_belongs_to_many :nations, :class_name => "Country"
1186 # has_and_belongs_to_many :categories, :join_table => "prods_cats"
1187 # has_and_belongs_to_many :categories, :readonly => true
1188 # has_and_belongs_to_many :active_projects, :join_table => 'developers_projects', :delete_sql =>
1189 # 'DELETE FROM developers_projects WHERE active=1 AND developer_id = #{id} AND project_id = #{record.id}'
1190 def has_and_belongs_to_many(association_id
, options
= {}, &extension
)
1191 reflection
= create_has_and_belongs_to_many_reflection(association_id
, options
, &extension
)
1192 collection_accessor_methods(reflection
, HasAndBelongsToManyAssociation
)
1194 # Don't use a before_destroy callback since users' before_destroy
1195 # callbacks will be executed after the association is wiped out.
1196 old_method
= "destroy_without_habtm_shim_for_#{reflection.name}"
1197 class_eval
<<-end_eval unless method_defined?(old_method)
1198 alias_method :#{old_method}, :destroy_without_callbacks # alias_method :destroy_without_habtm_shim_for_posts, :destroy_without_callbacks
1199 def destroy_without_callbacks # def destroy_without_callbacks
1200 #{reflection.name}.clear # posts.clear
1201 #{old_method} # destroy_without_habtm_shim_for_posts
1205 add_association_callbacks(reflection
.name
, options
)
1209 # Generates a join table name from two provided table names.
1210 # The names in the join table namesme end up in lexicographic order.
1212 # join_table_name("members", "clubs") # => "clubs_members"
1213 # join_table_name("members", "special_clubs") # => "members_special_clubs"
1214 def join_table_name(first_table_name
, second_table_name
)
1215 if first_table_name
< second_table_name
1216 join_table
= "#{first_table_name}_#{second_table_name}"
1218 join_table
= "#{second_table_name}_#{first_table_name}"
1221 table_name_prefix
+ join_table
+ table_name_suffix
1224 def association_accessor_methods(reflection
, association_proxy_class
)
1225 define_method(reflection
.name
) do |*params
|
1226 force_reload
= params
.first
unless params
.empty
?
1227 association
= association_instance_get(reflection
.name
)
1229 if association
.nil? || force_reload
1230 association
= association_proxy_class
.new(self, reflection
)
1231 retval
= association
.reload
1232 if retval
.nil? and association_proxy_class
== BelongsToAssociation
1233 association_instance_set(reflection
.name
, nil)
1236 association_instance_set(reflection
.name
, association
)
1239 association
.target
.nil? ? nil : association
1242 define_method("loaded_#{reflection.name}?") do
1243 association
= association_instance_get(reflection
.name
)
1244 association
&& association
.loaded
?
1247 define_method("#{reflection.name}=") do |new_value
|
1248 association
= association_instance_get(reflection
.name
)
1250 if association
.nil? || association
.target
!= new_value
1251 association
= association_proxy_class
.new(self, reflection
)
1254 if association_proxy_class
== HasOneThroughAssociation
1255 association
.create_through_record(new_value
)
1256 self.send(reflection
.name
, new_value
)
1258 association
.replace(new_value
)
1259 association_instance_set(reflection
.name
, new_value
.nil? ? nil : association
)
1263 define_method("set_#{reflection.name}_target") do |target
|
1264 return if target
.nil? and association_proxy_class
== BelongsToAssociation
1265 association
= association_proxy_class
.new(self, reflection
)
1266 association
.target
= target
1267 association_instance_set(reflection
.name
, association
)
1271 def collection_reader_method(reflection
, association_proxy_class
)
1272 define_method(reflection
.name
) do |*params
|
1273 force_reload
= params
.first
unless params
.empty
?
1274 association
= association_instance_get(reflection
.name
)
1277 association
= association_proxy_class
.new(self, reflection
)
1278 association_instance_set(reflection
.name
, association
)
1281 association
.reload
if force_reload
1286 define_method("#{reflection.name.to_s.singularize}_ids") do
1287 if send(reflection
.name
).loaded
? || reflection
.options
[:finder_sql]
1288 send(reflection
.name
).map(&:id)
1290 send(reflection
.name
).all(:select => "#{reflection.quoted_table_name}.#{reflection.klass.primary_key}").map(&:id)
1295 def collection_accessor_methods(reflection
, association_proxy_class
, writer
= true)
1296 collection_reader_method(reflection
, association_proxy_class
)
1299 define_method("#{reflection.name}=") do |new_value
|
1300 # Loads proxy class instance (defined in collection_reader_method) if not already loaded
1301 association
= send(reflection
.name
)
1302 association
.replace(new_value
)
1306 define_method("#{reflection.name.to_s.singularize}_ids=") do |new_value
|
1307 ids
= (new_value
|| []).reject
{ |nid
| nid
.blank
? }
1308 send("#{reflection.name}=", reflection
.class_name
.constantize
.find(ids
))
1313 def association_constructor_method(constructor
, reflection
, association_proxy_class
)
1314 define_method("#{constructor}_#{reflection.name}") do |*params
|
1315 attributees
= params
.first
unless params
.empty
?
1316 replace_existing
= params
[1].nil? ? true : params
[1]
1317 association
= association_instance_get(reflection
.name
)
1320 association
= association_proxy_class
.new(self, reflection
)
1321 association_instance_set(reflection
.name
, association
)
1324 if association_proxy_class
== HasOneAssociation
1325 association
.send(constructor
, attributees
, replace_existing
)
1327 association
.send(constructor
, attributees
)
1332 def find_with_associations(options
= {})
1333 catch
:invalid_query do
1334 join_dependency
= JoinDependency
.new(self, merge_includes(scope(:find, :include), options
[:include]), options
[:joins])
1335 rows
= select_all_rows(options
, join_dependency
)
1336 return join_dependency
.instantiate(rows
)
1341 # Creates before_destroy callback methods that nullify, delete or destroy
1342 # has_many associated objects, according to the defined :dependent rule.
1344 # See HasManyAssociation#delete_records. Dependent associations
1345 # delete children, otherwise foreign key is set to NULL.
1347 # The +extra_conditions+ parameter, which is not used within the main
1348 # Active Record codebase, is meant to allow plugins to define extra
1349 # finder conditions.
1350 def configure_dependency_for_has_many(reflection
, extra_conditions
= nil)
1351 if reflection
.options
.include?(:dependent)
1352 # Add polymorphic type if the :as option is present
1353 dependent_conditions
= []
1354 dependent_conditions
<< "#{reflection.primary_key_name} = \#{record.quoted_id}"
1355 dependent_conditions
<< "#{reflection.options[:as]}_type = '#{base_class.name}'" if reflection
.options
[:as]
1356 dependent_conditions
<< sanitize_sql(reflection
.options
[:conditions]) if reflection
.options
[:conditions]
1357 dependent_conditions
<< extra_conditions
if extra_conditions
1358 dependent_conditions
= dependent_conditions
.collect
{|where
| "(#{where})" }.join(" AND ")
1359 dependent_conditions
= dependent_conditions
.gsub('@', '\@')
1360 case reflection
.options
[:dependent]
1362 method_name
= "has_many_dependent_destroy_for_#{reflection.name}".to_sym
1363 define_method(method_name
) do
1364 send(reflection
.name
).each
{ |o
| o
.destroy
}
1366 before_destroy method_name
1369 before_destroy do |record| # before_destroy do |record|
1370 delete_all_has_many_dependencies(record, # delete_all_has_many_dependencies(record,
1371 "#{reflection.name}", # "posts",
1372 #{reflection.class_name}, # Post,
1373 %@#{dependent_conditions}@) # %@...@) # this is a string literal like %(...)
1378 before_destroy do |record| # before_destroy do |record|
1379 nullify_has_many_dependencies(record, # nullify_has_many_dependencies(record,
1380 "#{reflection.name}", # "posts",
1381 #{reflection.class_name}, # Post,
1382 "#{reflection.primary_key_name}", # "user_id",
1383 %@#{dependent_conditions}@) # %@...@) # this is a string literal like %(...)
1387 raise ArgumentError, "The :dependent option expects either :destroy, :delete_all, or :nullify (#{reflection.options[:dependent].inspect})"
1392 # Creates before_destroy callback methods that nullify, delete or destroy
1393 # has_one associated objects, according to the defined :dependent rule.
1394 def configure_dependency_for_has_one(reflection)
1395 if reflection.options.include?(:dependent)
1396 case reflection.options[:dependent]
1398 method_name = "has_one_dependent_destroy_for_#{reflection.name}".to_sym
1399 define_method(method_name) do
1400 association = send(reflection.name)
1401 association.destroy unless association.nil?
1403 before_destroy method_name
1405 method_name = "has_one_dependent_delete_for_#{reflection.name}".to_sym
1406 define_method(method_name) do
1407 # Retrieve the associated object and delete it. The retrieval
1408 # is necessary because there may be multiple associated objects
1409 # with foreign keys pointing to this object, and we only want
1410 # to delete the correct one, not all of them.
1411 association = send(reflection.name)
1412 association.delete unless association.nil?
1414 before_destroy method_name
1416 method_name = "has_one_dependent_nullify_for_#{reflection.name}".to_sym
1417 define_method(method_name) do
1418 association = send(reflection.name)
1419 association.update_attribute(reflection.primary_key_name, nil) unless association.nil?
1421 before_destroy method_name
1423 raise ArgumentError, "The :dependent option expects either :destroy, :delete or :nullify (#{reflection.options[:dependent].inspect})"
1428 def configure_dependency_for_belongs_to(reflection)
1429 if reflection.options.include?(:dependent)
1430 case reflection.options[:dependent]
1432 method_name = "belongs_to_dependent_destroy_for_#{reflection.name}".to_sym
1433 define_method(method_name) do
1434 association = send(reflection.name)
1435 association.destroy unless association.nil?
1437 after_destroy method_name
1439 method_name = "belongs_to_dependent_delete_for_#{reflection.name}".to_sym
1440 define_method(method_name) do
1441 association = send(reflection.name)
1442 association.delete unless association.nil?
1444 after_destroy method_name
1446 raise ArgumentError, "The :dependent option expects either :destroy or :delete (#{reflection.options[:dependent].inspect})"
1451 def delete_all_has_many_dependencies(record, reflection_name, association_class, dependent_conditions)
1452 association_class.delete_all(dependent_conditions)
1455 def nullify_has_many_dependencies(record, reflection_name, association_class, primary_key_name, dependent_conditions)
1456 association_class.update_all("#{primary_key_name} = NULL", dependent_conditions)
1459 mattr_accessor :valid_keys_for_has_many_association
1460 @@valid_keys_for_has_many_association = [
1461 :class_name, :table_name, :foreign_key, :primary_key,
1463 :select, :conditions, :include, :order, :group, :having, :limit, :offset,
1464 :as, :through, :source, :source_type,
1466 :finder_sql, :counter_sql,
1467 :before_add, :after_add, :before_remove, :after_remove,
1472 def create_has_many_reflection(association_id, options, &extension)
1473 options.assert_valid_keys(valid_keys_for_has_many_association)
1474 options[:extend] = create_extension_modules(association_id, extension, options[:extend])
1476 create_reflection(:has_many, association_id, options, self)
1479 mattr_accessor :valid_keys_for_has_one_association
1480 @@valid_keys_for_has_one_association = [
1481 :class_name, :foreign_key, :remote, :select, :conditions, :order,
1482 :include, :dependent, :counter_cache, :extend, :as, :readonly,
1483 :validate, :primary_key
1486 def create_has_one_reflection(association_id, options)
1487 options.assert_valid_keys(valid_keys_for_has_one_association)
1488 create_reflection(:has_one, association_id, options, self)
1491 def create_has_one_through_reflection(association_id, options)
1492 options.assert_valid_keys(
1493 :class_name, :foreign_key, :remote, :select, :conditions, :order, :include, :dependent, :counter_cache, :extend, :as, :through, :source, :source_type, :validate
1495 create_reflection(:has_one, association_id, options, self)
1498 mattr_accessor :valid_keys_for_belongs_to_association
1499 @@valid_keys_for_belongs_to_association = [
1500 :class_name, :foreign_key, :foreign_type, :remote, :select, :conditions,
1501 :include, :dependent, :counter_cache, :extend, :polymorphic, :readonly,
1505 def create_belongs_to_reflection(association_id, options)
1506 options.assert_valid_keys(valid_keys_for_belongs_to_association)
1507 reflection = create_reflection(:belongs_to, association_id, options, self)
1509 if options[:polymorphic]
1510 reflection.options[:foreign_type] ||= reflection.class_name.underscore + "_type"
1516 mattr_accessor :valid_keys_for_has_and_belongs_to_many_association
1517 @@valid_keys_for_has_and_belongs_to_many_association = [
1518 :class_name, :table_name, :join_table, :foreign_key, :association_foreign_key,
1519 :select, :conditions, :include, :order, :group, :having, :limit, :offset,
1521 :finder_sql, :counter_sql, :delete_sql, :insert_sql,
1522 :before_add, :after_add, :before_remove, :after_remove,
1527 def create_has_and_belongs_to_many_reflection(association_id, options, &extension)
1528 options.assert_valid_keys(valid_keys_for_has_and_belongs_to_many_association)
1530 options[:extend] = create_extension_modules(association_id, extension, options[:extend])
1532 reflection = create_reflection(:has_and_belongs_to_many, association_id, options, self)
1534 if reflection.association_foreign_key == reflection.primary_key_name
1535 raise HasAndBelongsToManyAssociationForeignKeyNeeded.new(reflection)
1538 reflection.options[:join_table] ||= join_table_name(undecorated_table_name(self.to_s), undecorated_table_name(reflection.class_name))
1543 def reflect_on_included_associations(associations)
1544 [ associations ].flatten.collect { |association| reflect_on_association(association.to_s.intern) }
1547 def guard_against_unlimitable_reflections(reflections, options)
1548 if (options[:offset] || options[:limit]) && !using_limitable_reflections?(reflections)
1551 "You can not use offset and limit together with has_many or has_and_belongs_to_many associations"
1556 def select_all_rows(options, join_dependency)
1557 connection.select_all(
1558 construct_finder_sql_with_included_associations(options, join_dependency),
1559 "#{name} Load Including Associations"
1563 def construct_finder_sql_with_included_associations(options, join_dependency)
1564 scope = scope(:find)
1565 sql = "SELECT #{column_aliases(join_dependency)} FROM #{(scope && scope[:from]) || options[:from] || quoted_table_name} "
1566 sql << join_dependency.join_associations.collect{|join| join.association_join }.join
1568 add_joins!(sql, options[:joins], scope)
1569 add_conditions!(sql, options[:conditions], scope)
1570 add_limited_ids_condition!(sql, options, join_dependency) if !using_limitable_reflections?(join_dependency.reflections) && ((scope && scope[:limit]) || options[:limit])
1572 add_group!(sql, options[:group], options[:having], scope)
1573 add_order!(sql, options[:order], scope)
1574 add_limit!(sql, options, scope) if using_limitable_reflections?(join_dependency.reflections)
1575 add_lock!(sql, options, scope)
1577 return sanitize_sql(sql)
1580 def add_limited_ids_condition!(sql, options, join_dependency)
1581 unless (id_list = select_limited_ids_list(options, join_dependency)).empty?
1582 sql << "#{condition_word(sql)} #{connection.quote_table_name table_name}.#{primary_key} IN (#{id_list}) "
1584 throw :invalid_query
1588 def select_limited_ids_list(options, join_dependency)
1589 pk = columns_hash[primary_key]
1591 connection.select_all(
1592 construct_finder_sql_for_association_limiting(options, join_dependency),
1593 "#{name} Load IDs For Limited Eager Loading"
1594 ).collect { |row| connection.quote(row[primary_key], pk) }.join(", ")
1597 def construct_finder_sql_for_association_limiting(options, join_dependency)
1598 scope = scope(:find)
1600 # Only join tables referenced in order or conditions since this is particularly slow on the pre-query.
1601 tables_from_conditions = conditions_tables(options)
1602 tables_from_order = order_tables(options)
1603 all_tables = tables_from_conditions + tables_from_order
1604 distinct_join_associations = all_tables.uniq.map{|table|
1605 join_dependency.joins_for_table_name(table)
1606 }.flatten.compact.uniq
1608 order = options[:order]
1609 if scoped_order = (scope && scope[:order])
1610 order = order ? "#{order}, #{scoped_order}" : scoped_order
1613 is_distinct = !options[:joins].blank? || include_eager_conditions?(options, tables_from_conditions) || include_eager_order?(options, tables_from_order)
1616 sql << connection.distinct("#{connection.quote_table_name table_name}.#{primary_key}", order)
1620 sql << " FROM #{connection.quote_table_name table_name} "
1623 sql << distinct_join_associations.collect { |assoc| assoc.association_join }.join
1624 add_joins!(sql, options[:joins], scope)
1627 add_conditions!(sql, options[:conditions], scope)
1628 add_group!(sql, options[:group], options[:having], scope)
1630 if order && is_distinct
1631 connection.add_order_by_for_association_limiting!(sql, :order => order)
1633 add_order!(sql, options[:order], scope)
1636 add_limit!(sql, options, scope)
1638 return sanitize_sql(sql)
1641 def tables_in_string(string)
1642 return [] if string.blank?
1643 string.scan(/([\.a-zA-Z_]+).?\./).flatten
1646 def conditions_tables(options)
1647 # look in both sets of conditions
1648 conditions = [scope(:find, :conditions), options[:conditions]].inject([]) do |all, cond|
1651 when Array then all << cond.first
1652 when Hash then all << cond.keys
1656 tables_in_string(conditions.join(' '))
1659 def order_tables(options)
1660 order = [options[:order], scope(:find, :order) ].join(", ")
1661 return [] unless order && order.is_a?(String)
1662 tables_in_string(order)
1665 def selects_tables(options)
1666 select = options[:select]
1667 return [] unless select && select.is_a?(String)
1668 tables_in_string(select)
1671 def joined_tables(options)
1672 scope = scope(:find)
1673 joins = options[:joins]
1674 merged_joins = scope && scope[:joins] && joins ? merge_joins(scope[:joins], joins) : (joins || scope && scope[:joins])
1675 [table_name] + case merged_joins
1676 when Symbol, Hash, Array
1677 if array_of_strings?(merged_joins)
1678 tables_in_string(merged_joins.join(' '))
1680 join_dependency = ActiveRecord::Associations::ClassMethods::InnerJoinDependency.new(self, merged_joins, nil)
1681 join_dependency.join_associations.collect {|join_association| [join_association.aliased_join_table_name, join_association.aliased_table_name]}.flatten.compact
1684 tables_in_string(merged_joins)
1688 # Checks if the conditions reference a table other than the current model table
1689 def include_eager_conditions?(options, tables = nil, joined_tables = nil)
1690 ((tables || conditions_tables(options)) - (joined_tables || joined_tables(options))).any?
1693 # Checks if the query order references a table other than the current model's table.
1694 def include_eager_order?(options, tables = nil, joined_tables = nil)
1695 ((tables || order_tables(options)) - (joined_tables || joined_tables(options))).any?
1698 def include_eager_select?(options, joined_tables = nil)
1699 (selects_tables(options) - (joined_tables || joined_tables(options))).any?
1702 def references_eager_loaded_tables?(options)
1703 joined_tables = joined_tables(options)
1704 include_eager_order?(options, nil, joined_tables) || include_eager_conditions?(options, nil, joined_tables) || include_eager_select?(options, joined_tables)
1707 def using_limitable_reflections?(reflections)
1708 reflections.reject { |r| [ :belongs_to, :has_one ].include?(r.macro) }.length.zero?
1711 def column_aliases(join_dependency)
1712 join_dependency.joins.collect{|join| join.column_names_with_alias.collect{|column_name, aliased_name|
1713 "#{connection.quote_table_name join.aliased_table_name}.#{connection.quote_column_name column_name} AS #{aliased_name}"}}.flatten.join(", ")
1716 def add_association_callbacks(association_name, options)
1717 callbacks = %w(before_add after_add before_remove after_remove)
1718 callbacks.each do |callback_name|
1719 full_callback_name = "#{callback_name}_for_#{association_name}"
1720 defined_callbacks = options[callback_name.to_sym]
1721 if options.has_key?(callback_name.to_sym)
1722 class_inheritable_reader full_callback_name.to_sym
1723 write_inheritable_attribute(full_callback_name.to_sym, [defined_callbacks].flatten)
1725 write_inheritable_attribute(full_callback_name.to_sym, [])
1730 def condition_word(sql)
1731 sql =~ /where/i ? " AND " : "WHERE "
1734 def create_extension_modules(association_id, block_extension, extensions)
1736 extension_module_name = "#{self.to_s.demodulize}#{association_id.to_s.camelize}AssociationExtension"
1739 self.parent.const_set(extension_module_name, Module.new(&block_extension))
1741 Array(extensions).push("#{self.parent}::#{extension_module_name}".constantize)
1747 class JoinDependency # :nodoc:
1748 attr_reader :joins, :reflections, :table_aliases
1750 def initialize(base, associations, joins)
1751 @joins = [JoinBase.new(base, joins)]
1752 @associations = associations
1754 @base_records_hash = {}
1755 @base_records_in_order = []
1756 @table_aliases = Hash.new { |aliases, table| aliases[table] = 0 }
1757 @table_aliases[base.table_name] = 1
1761 def join_associations
1769 def instantiate(rows)
1770 rows.each_with_index do |row, i|
1771 primary_id = join_base.record_id(row)
1772 unless @base_records_hash[primary_id]
1773 @base_records_in_order << (@base_records_hash[primary_id] = join_base.instantiate(row))
1775 construct(@base_records_hash[primary_id], @associations, join_associations.dup, row)
1777 remove_duplicate_results!(join_base.active_record, @base_records_in_order, @associations)
1778 return @base_records_in_order
1781 def remove_duplicate_results!(base, records, associations)
1784 reflection = base.reflections[associations]
1785 if reflection && [:has_many, :has_and_belongs_to_many].include?(reflection.macro)
1786 records.each { |record| record.send(reflection.name).target.uniq! }
1789 associations.each do |association|
1790 remove_duplicate_results!(base, records, association)
1793 associations.keys.each do |name|
1794 reflection = base.reflections[name]
1795 is_collection = [:has_many, :has_and_belongs_to_many].include?(reflection.macro)
1797 parent_records = records.map do |record|
1798 descendant = record.send(reflection.name)
1799 next unless descendant
1800 descendant.target.uniq! if is_collection
1804 remove_duplicate_results!(reflection.class_name.constantize, parent_records, associations[name]) unless parent_records.empty?
1809 def join_for_table_name(table_name)
1810 join = (@joins.select{|j|j.aliased_table_name == table_name.gsub(/^\"(.*)\"$/){$1} }.first) rescue nil
1811 return join unless join.nil?
1812 @joins.select{|j|j.is_a?(JoinAssociation) && j.aliased_join_table_name == table_name.gsub(/^\"(.*)\"$/){$1} }.first rescue nil
1815 def joins_for_table_name(table_name)
1816 join = join_for_table_name(table_name)
1818 if join && join.is_a?(JoinAssociation)
1820 if join.parent && join.parent.is_a?(JoinAssociation)
1821 result = joins_for_table_name(join.parent.aliased_table_name) +
1829 def build(associations, parent = nil)
1830 parent ||= @joins.last
1833 reflection = parent.reflections[associations.to_s.intern] or
1834 raise ConfigurationError, "Association named '#{ associations }' was not found; perhaps you misspelled it?"
1835 @reflections << reflection
1836 @joins << build_join_association(reflection, parent)
1838 associations.each do |association|
1839 build(association, parent)
1842 associations.keys.sort{|a,b|a.to_s<=>b.to_s}.each do |name|
1844 build(associations[name])
1847 raise ConfigurationError, associations.inspect
1851 # overridden in InnerJoinDependency subclass
1852 def build_join_association(reflection, parent)
1853 JoinAssociation.new(reflection, self, parent)
1856 def construct(parent, associations, joins, row)
1859 join = joins.detect{|j| j.reflection.name.to_s == associations.to_s && j.parent_table_name == parent.class.table_name }
1860 raise(ConfigurationError, "No such association") if join.nil?
1863 construct_association(parent, join, row)
1865 associations.each do |association|
1866 construct(parent, association, joins, row)
1869 associations.keys.sort{|a,b|a.to_s<=>b.to_s}.each do |name|
1870 join = joins.detect{|j| j.reflection.name.to_s == name.to_s && j.parent_table_name == parent.class.table_name }
1871 raise(ConfigurationError, "No such association") if join.nil?
1873 association = construct_association(parent, join, row)
1875 construct(association, associations[name], joins, row) if association
1878 raise ConfigurationError, associations.inspect
1882 def construct_association(record, join, row)
1883 case join.reflection.macro
1884 when :has_many, :has_and_belongs_to_many
1885 collection = record.send(join.reflection.name)
1888 return nil if record.id.to_s != join.parent.record_id(row).to_s or row[join.aliased_primary_key].nil?
1889 association = join.instantiate(row)
1890 collection.target.push(association)
1892 return if record.id.to_s != join.parent.record_id(row).to_s
1893 return if record.instance_variable_defined?("@#{join.reflection.name}")
1894 association = join.instantiate(row) unless row[join.aliased_primary_key].nil?
1895 record.send("set_#{join.reflection.name}_target", association)
1897 return if record.id.to_s != join.parent.record_id(row).to_s or row[join.aliased_primary_key].nil?
1898 association = join.instantiate(row)
1899 record.send("set_#{join.reflection.name}_target", association)
1901 raise ConfigurationError, "unknown macro: #{join.reflection.macro}"
1906 class JoinBase # :nodoc:
1907 attr_reader :active_record, :table_joins
1908 delegate :table_name, :column_names, :primary_key, :reflections, :sanitize_sql, :to => :active_record
1910 def initialize(active_record, joins = nil)
1911 @active_record = active_record
1913 @table_joins = joins
1920 def aliased_primary_key
1921 "#{aliased_prefix}_r0"
1924 def aliased_table_name
1925 active_record.table_name
1928 def column_names_with_alias
1929 unless defined?(@column_names_with_alias)
1930 @column_names_with_alias = []
1932 ([primary_key] + (column_names - [primary_key])).each_with_index do |column_name, i|
1933 @column_names_with_alias << [column_name, "#{aliased_prefix}_r#{i}"]
1937 @column_names_with_alias
1940 def extract_record(row)
1941 column_names_with_alias.inject({}){|record, (cn, an)| record[cn] = row[an]; record}
1945 row[aliased_primary_key]
1948 def instantiate(row)
1949 @cached_record[record_id(row)] ||= active_record.send(:instantiate, extract_record(row))
1953 class JoinAssociation < JoinBase # :nodoc:
1954 attr_reader :reflection, :parent, :aliased_table_name, :aliased_prefix, :aliased_join_table_name, :parent_table_name
1955 delegate :options, :klass, :through_reflection, :source_reflection, :to => :reflection
1957 def initialize(reflection, join_dependency, parent = nil)
1958 reflection.check_validity!
1959 if reflection.options[:polymorphic]
1960 raise EagerLoadPolymorphicError.new(reflection)
1963 super(reflection.klass)
1964 @join_dependency = join_dependency
1966 @reflection = reflection
1967 @aliased_prefix = "t#{ join_dependency.joins.size }"
1968 @parent_table_name = parent.active_record.table_name
1969 @aliased_table_name = aliased_table_name_for(table_name)
1971 if reflection.macro == :has_and_belongs_to_many
1972 @aliased_join_table_name = aliased_table_name_for(reflection.options[:join_table], "_join")
1975 if [:has_many, :has_one].include?(reflection.macro) && reflection.options[:through]
1976 @aliased_join_table_name = aliased_table_name_for(reflection.through_reflection.klass.table_name, "_join")
1980 def association_join
1981 connection = reflection.active_record.connection
1982 join = case reflection.macro
1983 when :has_and_belongs_to_many
1984 " #{join_type} %s ON %s.%s = %s.%s " % [
1985 table_alias_for(options[:join_table], aliased_join_table_name),
1986 connection.quote_table_name(aliased_join_table_name),
1987 options[:foreign_key] || reflection.active_record.to_s.foreign_key,
1988 connection.quote_table_name(parent.aliased_table_name),
1989 reflection.active_record.primary_key] +
1990 " #{join_type} %s ON %s.%s = %s.%s " % [
1991 table_name_and_alias,
1992 connection.quote_table_name(aliased_table_name),
1994 connection.quote_table_name(aliased_join_table_name),
1995 options[:association_foreign_key] || klass.to_s.foreign_key
1997 when :has_many, :has_one
1999 when reflection.options[:through]
2000 through_conditions = through_reflection.options[:conditions] ? "AND #{interpolate_sql(sanitize_sql(through_reflection.options[:conditions]))}" : ''
2002 jt_foreign_key = jt_as_extra = jt_source_extra = jt_sti_extra = nil
2003 first_key = second_key = as_extra = nil
2005 if through_reflection.options[:as] # has_many :through against a polymorphic join
2006 jt_foreign_key = through_reflection.options[:as].to_s + '_id'
2007 jt_as_extra = " AND %s.%s = %s" % [
2008 connection.quote_table_name(aliased_join_table_name),
2009 connection.quote_column_name(through_reflection.options[:as].to_s + '_type'),
2010 klass.quote_value(parent.active_record.base_class.name)
2013 jt_foreign_key = through_reflection.primary_key_name
2016 case source_reflection.macro
2018 if source_reflection.options[:as]
2019 first_key = "#{source_reflection.options[:as]}_id"
2020 second_key = options[:foreign_key] || primary_key
2021 as_extra = " AND %s.%s = %s" % [
2022 connection.quote_table_name(aliased_table_name),
2023 connection.quote_column_name("#{source_reflection.options[:as]}_type"),
2024 klass.quote_value(source_reflection.active_record.base_class.name)
2027 first_key = through_reflection.klass.base_class.to_s.foreign_key
2028 second_key = options[:foreign_key] || primary_key
2031 unless through_reflection.klass.descends_from_active_record?
2032 jt_sti_extra = " AND %s.%s = %s" % [
2033 connection.quote_table_name(aliased_join_table_name),
2034 connection.quote_column_name(through_reflection.active_record.inheritance_column),
2035 through_reflection.klass.quote_value(through_reflection.klass.sti_name)]
2038 first_key = primary_key
2039 if reflection.options[:source_type]
2040 second_key = source_reflection.association_foreign_key
2041 jt_source_extra = " AND %s.%s = %s" % [
2042 connection.quote_table_name(aliased_join_table_name),
2043 connection.quote_column_name(reflection.source_reflection.options[:foreign_type]),
2044 klass.quote_value(reflection.options[:source_type])
2047 second_key = source_reflection.primary_key_name
2051 " #{join_type} %s ON (%s.%s = %s.%s%s%s%s) " % [
2052 table_alias_for(through_reflection.klass.table_name, aliased_join_table_name),
2053 connection.quote_table_name(parent.aliased_table_name),
2054 connection.quote_column_name(parent.primary_key),
2055 connection.quote_table_name(aliased_join_table_name),
2056 connection.quote_column_name(jt_foreign_key),
2057 jt_as_extra, jt_source_extra, jt_sti_extra
2059 " #{join_type} %s ON (%s.%s = %s.%s%s) " % [
2060 table_name_and_alias,
2061 connection.quote_table_name(aliased_table_name),
2062 connection.quote_column_name(first_key),
2063 connection.quote_table_name(aliased_join_table_name),
2064 connection.quote_column_name(second_key),
2068 when reflection.options[:as] && [:has_many, :has_one].include?(reflection.macro)
2069 " #{join_type} %s ON %s.%s = %s.%s AND %s.%s = %s" % [
2070 table_name_and_alias,
2071 connection.quote_table_name(aliased_table_name),
2072 "#{reflection.options[:as]}_id",
2073 connection.quote_table_name(parent.aliased_table_name),
2075 connection.quote_table_name(aliased_table_name),
2076 "#{reflection.options[:as]}_type",
2077 klass.quote_value(parent.active_record.base_class.name)
2080 foreign_key = options[:foreign_key] || reflection.active_record.name.foreign_key
2081 " #{join_type} %s ON %s.%s = %s.%s " % [
2082 table_name_and_alias,
2085 parent.aliased_table_name,
2086 reflection.options[:primary_key] || parent.primary_key
2090 " #{join_type} %s ON %s.%s = %s.%s " % [
2091 table_name_and_alias,
2092 connection.quote_table_name(aliased_table_name),
2093 reflection.klass.primary_key,
2094 connection.quote_table_name(parent.aliased_table_name),
2095 options[:foreign_key] || reflection.primary_key_name
2100 join << %(AND %s) % [
2101 klass.send(:type_condition, aliased_table_name)] unless klass.descends_from_active_record?
2103 [through_reflection, reflection].each do |ref|
2104 join << "AND #{interpolate_sql(sanitize_sql(ref.options[:conditions]))} " if ref && ref.options[:conditions]
2112 def aliased_table_name_for(name, suffix = nil)
2113 if !parent.table_joins.blank? && parent.table_joins.to_s.downcase =~ %r{join(\s+\w+)?\s+#{active_record.connection.quote_table_name name.downcase}\son}
2114 @join_dependency.table_aliases[name] += 1
2117 unless @join_dependency.table_aliases[name].zero?
2118 # if the table name has been used, then use an alias
2119 name = active_record.connection.table_alias_for "#{pluralize(reflection.name)}_#{parent_table_name}#{suffix}"
2120 table_index = @join_dependency.table_aliases[name]
2121 @join_dependency.table_aliases[name] += 1
2122 name = name[0..active_record.connection.table_alias_length-3] + "_#{table_index+1}" if table_index > 0
2124 @join_dependency.table_aliases[name] += 1
2130 def pluralize(table_name)
2131 ActiveRecord::Base.pluralize_table_names ? table_name.to_s.pluralize : table_name
2134 def table_alias_for(table_name, table_alias)
2135 "#{reflection.active_record.connection.quote_table_name(table_name)} #{table_alias if table_name != table_alias}".strip
2138 def table_name_and_alias
2139 table_alias_for table_name, @aliased_table_name
2142 def interpolate_sql(sql)
2143 instance_eval("%@#{sql.gsub('@', '\@')}@")
2153 class InnerJoinDependency < JoinDependency # :nodoc:
2155 def build_join_association(reflection, parent)
2156 InnerJoinAssociation.new(reflection, self, parent)
2159 class InnerJoinAssociation < JoinAssociation