Allow ordering of calculated results and/or grouped fields in calculations...

Allow ordering of calculated results and/or grouped fields in calculations [solo@gatelys.com] closes #4228

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3865 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

 *SVN*
 
+* Allow ordering of calculated results and/or grouped fields in calculations [solo@gatelys.com]
+
 * Dynamically set allow_concurrency.  #4044 [Stefan Kaes]
 
 * Added Base#to_xml that'll turn the current record into a XML representation [DHH]. Example:

activerecord/lib/active_record/calculations.rb

@@ -151,6 +151,7 @@ def construct_calculation_sql(aggregate, aggregate_alias, options)
         add_conditions!(sql, options[:conditions])
         sql << " GROUP BY #{options[:group_field]}" if options[:group]
         sql << " HAVING #{options[:having]}" if options[:group] && options[:having]
+        sql << " ORDER BY #{options[:order]}" if options[:order]
         sql.join
       end
 

activerecord/test/calculations_test.rb

@@ -37,6 +37,17 @@ def test_should_group_by_summed_field
     assert_equal 60,   c[2]
   end
 
+  def test_should_order_by_grouped_field
+    c = Account.sum(:credit_limit, :group => :firm_id, :order => "firm_id")
+    assert_equal [nil, 1, 2, 6], c.keys
+  end
+
+  def test_should_order_by_calculation
+    c = Account.sum(:credit_limit, :group => :firm_id, :order => "sum_credit_limit desc, firm_id")
+    assert_equal [105, 60, 50, 50], c.keys.collect { |k| c[k] }
+    assert_equal [6, 2, nil, 1], c.keys
+  end
+
   def test_should_group_by_summed_field_having_condition
     c = Account.sum(:credit_limit, :group => :firm_id, 
                                    :having => 'sum(credit_limit) > 50')