Ensure that the :uniq option for has_many :through associations retains the order. #10463 [remvee]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8376 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

 *SVN*
 
+* Ensure that the :uniq option for has_many :through associations retains the order.  #10463 [remvee]
+
 * Base.exists? doesn't rescue exceptions to avoid hiding SQL errors.  #10458 [Michael Klishin]
 
 * Documentation: Active Record exceptions, destroy_all and delete_all.  #10444, #10447 [Michael Klishin]

activerecord/lib/active_record/associations/has_many_through_association.rb

@@ -148,7 +148,8 @@ def find_target
             :include    => @reflection.options[:include] || @reflection.source_reflection.options[:include]
           )
 
-          @reflection.options[:uniq] ? records.to_set.to_a : records
+          records.uniq! if @reflection.options[:uniq]
+          records
         end
 
         # Construct attributes for associate pointing to owner.

activerecord/test/associations/join_model_test.rb

@@ -539,6 +539,12 @@ def test_has_many_through_sum_uses_calculations
   def test_has_many_through_has_many_with_sti
     assert_equal [comments(:does_it_hurt)], authors(:david).special_post_comments
   end
+  
+  def test_uniq_has_many_through_should_retain_order
+    comment_ids = authors(:david).comments.map(&:id)
+    assert_equal comment_ids.sort, authors(:david).ordered_uniq_comments.map(&:id)
+    assert_equal comment_ids.sort.reverse, authors(:david).ordered_uniq_comments_desc.map(&:id)
+  end
 
   private
     # create dynamic Post models to allow different dependency options

activerecord/test/fixtures/author.rb

@@ -18,6 +18,8 @@ def testing_proxy_target
   has_many :comments_desc, :through => :posts, :source => :comments, :order => 'comments.id DESC'
   has_many :limited_comments, :through => :posts, :source => :comments, :limit => 1
   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 :special_posts
   has_many :special_post_comments, :through => :special_posts, :source => :comments