Allow has_many :through associations to find the source association b…

…y setting a custom class (closes #4307) [jonathan@bluewire.net.nz]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3973 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

@@ -1,5 +1,7 @@
 *SVN*
 
+* Allow has_many :through associations to find the source association by setting a custom class (closes #4307) [jonathan@bluewire.net.nz]
+
 * Eager Loading support added for has_many :through => :has_many associations (see below).  [Rick Olson]
 
 * Allow has_many :through to work on has_many associations (closes #3864) [sco@scottraymond.net]  Example:

activerecord/lib/active_record/associations.rb

@@ -32,13 +32,13 @@ def message
   end
 
   class HasManyThroughSourceAssociationNotFoundError < ActiveRecordError
-    def initialize(through_reflection, source_reflection_name)
+    def initialize(through_reflection, source_reflection_names)
       @through_reflection      = through_reflection
-      @source_reflection_name  = source_reflection_name
+      @source_reflection_names = source_reflection_names
     end
 
     def message
-      "Could not find the source association '#{@source_reflection_name}' in model #{@through_reflection.klass}"
+      "Could not find the source associations #{@source_reflection_names.to_sentence} in model #{@through_reflection.klass}"
     end
   end
 

activerecord/lib/active_record/reflection.rb

@@ -144,21 +144,26 @@ def through_reflection
         @through_reflection ||= options[:through] ? active_record.reflect_on_association(options[:through]) : false
       end
 
-      def source_reflection_name
-        @source_reflection_name ||= name.to_s.singularize.to_sym
+      # Gets an array of possible :through reflection names
+      #
+      #   [singularized, pluralized]
+      def source_reflection_names
+        @source_reflection_names ||= (options[:class_name] ? 
+          [options[:class_name].underscore, options[:class_name].underscore.pluralize] : 
+          [name.to_s.singularize, name]
+        ).collect { |n| n.to_sym }
       end
 
-      # Gets the source of the through reflection.  (The :tags association on Tagging below)
+      # Gets the source of the through reflection.  It checks both a singularized and pluralized form for :belongs_to or :has_many.
+      # (The :tags association on Tagging below)
       # 
       #   class Post
       #     has_many :tags, :through => :taggings
       #   end
       #
       def source_reflection
         return nil unless through_reflection
-        @source_reflection ||= \
-          through_reflection.klass.reflect_on_association(source_reflection_name) || # has_many :through a :belongs_to
-          through_reflection.klass.reflect_on_association(name)                      # has_many :through a :has_many
+        @source_reflection ||= source_reflection_names.collect { |name| through_reflection.klass.reflect_on_association(name) }.compact.first
       end
 
       def check_validity!
@@ -168,7 +173,7 @@ def check_validity!
           end
 
           if source_reflection.nil?
-            raise HasManyThroughSourceAssociationNotFoundError.new(through_reflection, source_reflection_name)
+            raise HasManyThroughSourceAssociationNotFoundError.new(through_reflection, source_reflection_names)
           end
 
           if source_reflection.options[:polymorphic]

activerecord/test/associations_join_model_test.rb

@@ -55,7 +55,11 @@ def test_polymorphic_has_many_create_model_with_inheritance_and_custom_base_clas
   def test_polymorphic_has_many_going_through_join_model_with_inheritance
     assert_equal tags(:general), posts(:thinking).tags.first
   end
-
+
+  def test_polymorphic_has_many_going_through_join_model_with_inheritance_with_custom_class_name
+    assert_equal tags(:general), posts(:thinking).funky_tags.first
+  end
+
   def test_polymorphic_has_many_create_model_with_inheritance
     post = posts(:thinking)
     assert_instance_of SpecialPost, post
@@ -234,6 +238,10 @@ def test_has_many_through_has_many_find_all
     assert_equal comments(:greetings), authors(:david).comments.find(:all, :order => 'comments.id').first
   end
 
+  def test_has_many_through_has_many_find_all_with_custom_class
+    assert_equal comments(:greetings), authors(:david).funky_comments.find(:all, :order => 'comments.id').first
+  end
+
   def test_has_many_through_has_many_find_first
     assert_equal comments(:greetings), authors(:david).comments.find(:first, :order => 'comments.id')
   end

activerecord/test/fixtures/author.rb

@@ -4,6 +4,7 @@ class Author < ActiveRecord::Base
   has_many :posts_with_categories, :include => :categories, :class_name => "Post"
   has_many :posts_with_comments_and_categories, :include => [ :comments, :categories ], :order => "posts.id", :class_name => "Post"
   has_many :comments, :through => :posts
+  has_many :funky_comments, :through => :posts, :class_name => 'Comment'
 
   has_many :special_posts,        :class_name => "Post"
   has_many :hello_posts,          :class_name => "Post", :conditions=>"\#{aliased_table_name}.body = 'hello'"

activerecord/test/fixtures/post.rb

@@ -22,6 +22,7 @@ def find_most_recent
 
   has_many :taggings, :as => :taggable
   has_many :tags, :through => :taggings
+  has_many :funky_tags, :through => :taggings, :class_name => 'Tag'
   has_many :super_tags, :through => :taggings
   has_one :tagging, :as => :taggable