diff options
Diffstat (limited to 'activerecord/lib/active_record/associations.rb')
| -rw-r--r-- | activerecord/lib/active_record/associations.rb | 72 |
1 files changed, 57 insertions, 15 deletions
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb index e91cbd7f33..ec5b41a3e7 100644 --- a/activerecord/lib/active_record/associations.rb +++ b/activerecord/lib/active_record/associations.rb @@ -52,14 +52,6 @@ module ActiveRecord end end - class HasManyThroughSourceAssociationMacroError < ActiveRecordError #:nodoc: - def initialize(reflection) - through_reflection = reflection.through_reflection - source_reflection = reflection.source_reflection - super("Invalid source reflection macro :#{source_reflection.macro}#{" :through" if source_reflection.options[:through]} for has_many #{reflection.name.inspect}, :through => #{through_reflection.name.inspect}. Use :source to specify the source reflection.") - end - end - class HasManyThroughCantAssociateThroughHasOneOrManyReflection < ActiveRecordError #:nodoc: def initialize(owner, reflection) super("Cannot modify association '#{owner.class.name}##{reflection.name}' because the source reflection class '#{reflection.source_reflection.class_name}' is associated to '#{reflection.through_reflection.class_name}' via :#{reflection.source_reflection.macro}.") @@ -78,6 +70,12 @@ module ActiveRecord end end + class HasManyThroughNestedAssociationsAreReadonly < ActiveRecordError #:nodoc + def initialize(owner, reflection) + super("Cannot modify association '#{owner.class.name}##{reflection.name}' because it goes through more than one other association.") + end + end + class HasAndBelongsToManyAssociationWithPrimaryKeyError < ActiveRecordError #:nodoc: def initialize(reflection) super("Primary key is not allowed in a has_and_belongs_to_many join table (#{reflection.options[:join_table]}).") @@ -144,6 +142,7 @@ module ActiveRecord autoload :Preloader, 'active_record/associations/preloader' autoload :JoinDependency, 'active_record/associations/join_dependency' + autoload :AliasTracker, 'active_record/associations/alias_tracker' # Clears out the association cache. def clear_association_cache #:nodoc: @@ -548,6 +547,49 @@ module ActiveRecord # belongs_to :tag, :inverse_of => :taggings # end # + # === Nested Associations + # + # You can actually specify *any* association with the <tt>:through</tt> option, including an + # association which has a <tt>:through</tt> option itself. For example: + # + # class Author < ActiveRecord::Base + # has_many :posts + # has_many :comments, :through => :posts + # has_many :commenters, :through => :comments + # end + # + # class Post < ActiveRecord::Base + # has_many :comments + # end + # + # class Comment < ActiveRecord::Base + # belongs_to :commenter + # end + # + # @author = Author.first + # @author.commenters # => People who commented on posts written by the author + # + # An equivalent way of setting up this association this would be: + # + # class Author < ActiveRecord::Base + # has_many :posts + # has_many :commenters, :through => :posts + # end + # + # class Post < ActiveRecord::Base + # has_many :comments + # has_many :commenters, :through => :comments + # end + # + # class Comment < ActiveRecord::Base + # belongs_to :commenter + # end + # + # When using nested association, you will not be able to modify the association because there + # is not enough information to know what modification to make. For example, if you tried to + # add a <tt>Commenter</tt> in the example above, there would be no way to tell how to set up the + # intermediate <tt>Post</tt> and <tt>Comment</tt> objects. + # # === Polymorphic Associations # # Polymorphic associations on models are not restricted on what types of models they @@ -1068,10 +1110,10 @@ module ActiveRecord # [:as] # Specifies a polymorphic interface (See <tt>belongs_to</tt>). # [:through] - # Specifies a join model through which to perform the query. Options for <tt>:class_name</tt>, + # Specifies an association through which to perform the query. This can be any other type + # of association, including other <tt>:through</tt> associations. Options for <tt>:class_name</tt>, # <tt>:primary_key</tt> and <tt>:foreign_key</tt> are ignored, as the association uses the - # source reflection. You can only use a <tt>:through</tt> query through a <tt>belongs_to</tt>, - # <tt>has_one</tt> or <tt>has_many</tt> association on the join model. + # source reflection. # # If the association on the join model is a +belongs_to+, the collection can be modified # and the records on the <tt>:through</tt> model will be automatically created and removed @@ -1198,10 +1240,10 @@ module ActiveRecord # you want to do a join but not include the joined columns. Do not forget to include the # primary and foreign keys, otherwise it will raise an error. # [:through] - # Specifies a Join Model through which to perform the query. Options for <tt>:class_name</tt> - # and <tt>:foreign_key</tt> are ignored, as the association uses the source reflection. You - # can only use a <tt>:through</tt> query through a <tt>has_one</tt> or <tt>belongs_to</tt> - # association on the join model. + # Specifies a Join Model through which to perform the query. Options for <tt>:class_name</tt>, + # <tt>:primary_key</tt>, and <tt>:foreign_key</tt> are ignored, as the association uses the + # source reflection. You can only use a <tt>:through</tt> query through a <tt>has_one</tt> + # or <tt>belongs_to</tt> association on the join model. # [:source] # Specifies the source association name used by <tt>has_one :through</tt> queries. # Only use it if the name cannot be inferred from the association. |