associations/collection_proxy.rb

gistfile1.rb

  1 module ActiveRecord
  2   module Associations
  3     # Association proxies in Active Record are middlemen between the object that
  4     # holds the association, known as the <tt>@owner</tt>, and the actual associated
  5     # object, known as the <tt>@target</tt>. The kind of association any proxy is
  6     # about is available in <tt>@reflection</tt>. That's an instance of the class
  7     # ActiveRecord::Reflection::AssociationReflection.
  8     #
  9     # For example, given
 10     #
 11     #   class Blog < ActiveRecord::Base
 12     #     has_many :posts
 13     #   end
 14     #
 15     #   blog = Blog.find(:first)
 16     #
 17     # the association proxy in <tt>blog.posts</tt> has the object in +blog+ as
 18     # <tt>@owner</tt>, the collection of its posts as <tt>@target</tt>, and
 19     # the <tt>@reflection</tt> object represents a <tt>:has_many</tt> macro.
 20     #
 21     # This class has most of the basic instance methods removed, and delegates
 22     # unknown methods to <tt>@target</tt> via <tt>method_missing</tt>. As a
 23     # corner case, it even removes the +class+ method and that's why you get
 24     #
 25     #   blog.posts.class # => Array
 26     #
 27     # though the object behind <tt>blog.posts</tt> is not an Array, but an
 28     # ActiveRecord::Associations::HasManyAssociation.
 29     #
 30     # The <tt>@target</tt> object is not \loaded until needed. For example,
 31     #
 32     #   blog.posts.count
 33     #
 34     # is computed directly through SQL and does not trigger by itself the
 35     # instantiation of the actual post records.
 36     class CollectionProxy # :nodoc: