Merge r8778 from trunk: fix calculations on associations with custom …

…:foreign_key. References rails#8117.

git-svn-id: http://svn-commit.rubyonrails.org/rails/branches/2-0-stable@8779 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/calculations.rb

@@ -213,7 +213,7 @@ def execute_grouped_calculation(operation, column_name, column, options) #:nodoc
           group_attr      = options[:group].to_s
           association     = reflect_on_association(group_attr.to_sym)
           associated      = association && association.macro == :belongs_to # only count belongs_to associations
-          group_field     = (associated ? "#{options[:group]}_id" : options[:group]).to_s
+          group_field     = associated ? association.primary_key_name : group_attr
           group_alias     = column_alias_for(group_field)
           group_column    = column_for group_field
           sql             = construct_calculation_sql(operation, column_name, options.merge(:group_field => group_field, :group_alias => group_alias))

activerecord/test/calculations_test.rb

@@ -159,7 +159,15 @@ def test_should_group_by_association_with_non_numeric_foreign_key
       assert_equal 1, c.first.last
     end
   end
-
+
+  def test_should_calculate_grouped_association_with_foreign_key_option
+    Account.belongs_to :another_firm, :class_name => 'Firm', :foreign_key => 'firm_id'
+    c = Account.count(:all, :group => :another_firm)
+    assert_equal 1, c[companies(:first_firm)]
+    assert_equal 2, c[companies(:rails_core)]
+    assert_equal 1, c[companies(:first_client)]
+  end
+
   def test_should_not_modify_options_when_using_includes
     options = {:conditions => 'companies.id > 1', :include => :firm}
     options_copy = options.dup