Ensure that ActiveRecord::Calculations disambiguates field names with the table name. Closes #11027 [cavalle]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@9018 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

3 files changed, 11 insertions, 0 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index f999877be8..8026f24023 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Ensure that ActiveRecord::Calculations disambiguates field names with the table name.  #11027 [cavalle]
+
 * Added add/remove_timestamps to the schema statements for adding the created_at/updated_at columns on existing tables #11129 [jramirez]
 
 * Added ActiveRecord::Base.find(:last) #11338 [miloops]
diff --git a/activerecord/lib/active_record/calculations.rb b/activerecord/lib/active_record/calculations.rb
index c8c8d42def..fc61a221a1 100644
--- a/activerecord/lib/active_record/calculations.rb
+++ b/activerecord/lib/active_record/calculations.rb
@@ -155,6 +155,7 @@ module ActiveRecord
           scope           = scope(:find)
           merged_includes = merge_includes(scope ? scope[:include] : [], options[:include])
           aggregate_alias = column_alias_for(operation, column_name)
+          column_name     = "#{connection.quote_table_name(table_name)}.#{column_name}" unless column_name == "*" || column_name.to_s.include?('.')
 
           if operation == 'count'
             if merged_includes.any?
diff --git a/activerecord/test/cases/associations/join_model_test.rb b/activerecord/test/cases/associations/join_model_test.rb
index c24a94bfc4..810e477ac0 100644
--- a/activerecord/test/cases/associations/join_model_test.rb
+++ b/activerecord/test/cases/associations/join_model_test.rb
@@ -544,6 +544,14 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     assert_nothing_raised { authors(:david).comments.sum(:post_id) }
   end
 
+  def test_calculations_on_has_many_through_should_disambiguate_fields
+    assert_nothing_raised { authors(:david).categories.maximum(:id) }
+  end
+  
+  def test_calculations_on_has_many_through_should_not_disambiguate_fields_unless_necessary
+    assert_nothing_raised { authors(:david).categories.maximum("categories.id") }
+  end
+
   def test_has_many_through_has_many_with_sti
     assert_equal [comments(:does_it_hurt)], authors(:david).special_post_comments
   end