Revert r8742: remove has_many with :group option since it has sketchy…

… sql support. Closes #10480.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8790 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/associations.rb

@@ -55,12 +55,6 @@ def initialize(owner, reflection)
     end
   end
 
-  class HasManyThroughCantCountOnColumnForGroupedAssociation < ActiveRecordError #:nodoc:
-    def initialize(owner, reflection, column_name)
-      super("Cannot count on column '#{column_name}' for association '#{owner.class.name}##{reflection.name}' grouped by '#{reflection.options[:group]}'.")
-    end
-  end
-
   class EagerLoadPolymorphicError < ActiveRecordError #:nodoc:
     def initialize(reflection)
       super("Can not eagerly load the polymorphic association #{reflection.name.inspect}")

activerecord/lib/active_record/associations/has_many_through_association.rb

@@ -124,15 +124,6 @@ def count(*args)
           column_name = "#{@reflection.quoted_table_name}.#{@reflection.klass.primary_key}" if column_name == :all
           options.merge!(:distinct => true) 
         end
-
-        if @reflection.options[:group]
-          unless column_name == :all
-            raise HasManyThroughCantCountOnColumnForGroupedAssociation.new(@owner, @reflection, column_name)
-          end
-          column_name = @reflection.options[:group]
-          options.merge!(:distinct => true)
-        end
-
         @reflection.klass.send(:with_scope, construct_scope) { @reflection.klass.count(column_name, options) } 
       end
 

activerecord/test/cases/associations/join_model_test.rb

@@ -603,21 +603,6 @@ def test_belongs_to_shared_parent
     end
   end
 
-  def test_group_has_many_through_should_use_group_for_count
-    using_length = authors(:david).reload.grouped_comments.length           # all associated comments are read first
-    using_count = authors(:david).reload.grouped_comments.count             # associated comments are only counted
-    assert_equal using_count, using_length
-
-    commented_posts = authors(:david).comments.map(&:post).uniq.size        # count commented posts manually
-    assert_equal commented_posts, authors(:david).grouped_comments.count
-  end
-
-  def test_group_has_many_through_should_not_allow_column_name_for_count
-    assert_raises ActiveRecord::HasManyThroughCantCountOnColumnForGroupedAssociation do
-      authors(:david).grouped_comments.count(:id)
-    end
-  end
-
   private
     # create dynamic Post models to allow different dependency options
     def find_post_with_dependency(post_id, association, association_name, dependency)

activerecord/test/models/author.rb

@@ -20,7 +20,6 @@ def testing_proxy_target
   has_many :funky_comments, :through => :posts, :source => :comments
   has_many :ordered_uniq_comments, :through => :posts, :source => :comments, :uniq => true, :order => 'comments.id'
   has_many :ordered_uniq_comments_desc, :through => :posts, :source => :comments, :uniq => true, :order => 'comments.id DESC'
-  has_many :grouped_comments, :through => :posts, :source => :comments, :group => 'comments.post_id'
 
   has_many :special_posts
   has_many :special_post_comments, :through => :special_posts, :source => :comments