diff options
Diffstat (limited to 'activerecord/lib/active_record/associations/association_proxy.rb')
| -rw-r--r-- | activerecord/lib/active_record/associations/association_proxy.rb | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations/association_proxy.rb b/activerecord/lib/active_record/associations/association_proxy.rb index 421ddc15ee..26274fff93 100644 --- a/activerecord/lib/active_record/associations/association_proxy.rb +++ b/activerecord/lib/active_record/associations/association_proxy.rb @@ -1,5 +1,50 @@ module ActiveRecord module Associations + # This is the root class of all association proxies: + # + # AssociationProxy + # BelongsToAssociation + # HasOneAssociation + # BelongsToPolymorphicAssociation + # AssociationCollection + # HasManyAssociation + # HasAndBelongsToManyAssociation + # HasManyThroughAssociation + # HasOneThroughAssociation + # + # Association proxies in Active Record are middlemen between the object that + # holds the association, known as the <tt>@owner</tt>, and the actual associated + # object, known as the <tt>@target</tt>. The kind of association any proxy is + # about is available in <tt>@reflection</tt>. That's an instance of the class + # ActiveRecord::Reflection::AssociationReflection. + # + # For example, given + # + # class Blog < ActiveRecord::Base + # has_many :posts + # end + # + # blog = Blog.find(:first) + # + # the association proxy in <tt>blog.posts</tt> has the object in +blog+ as + # <tt>@owner</tt>, the collection of its posts as <tt>@target</tt>, and + # the <tt>@reflection</tt> object represents a <tt>:has_many</tt> macro. + # + # This class has most of the basic instance methods removed, and delegates + # unknown methods to <tt>@target</tt> via <tt>method_missing</tt>. As a + # corner case, it even removes the +class+ method and that's why you get + # + # blog.posts.class # => Array + # + # though the object behind <tt>blog.posts</tt> is not an Array, but an + # ActiveRecord::Associations::HasManyAssociation. + # + # The <tt>@target</tt> object is not loaded until needed. For example, + # + # blog.posts.count + # + # is computed directly through SQL and does not trigger by itself the + # instantiation of the actual post records. class AssociationProxy #:nodoc: alias_method :proxy_respond_to?, :respond_to? alias_method :proxy_extend, :extend |