commit d97a95fc1895fe4c189c1eddc223b13934c648f3
Author: Nolan Eakins <sneakin@AR3.local>
Date:   Wed Apr 8 14:42:28 2009 -0400

    Fixes #2457 by checking to see if only the hour and minute were passed to the writter and fills in the date if that's the case.

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 2a53851..7d2ac5b 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -3024,6 +3024,13 @@ module ActiveRecord #:nodoc:
       end
 
       def instantiate_time_object(name, values)
+        if values.length == 2
+          # We only got the hour and minute, such as from
+          # ActionView::DateHelper#time_select so we'll add the missing
+          # info.
+          values = [ Date.today.year, Date.today.month, Date.today.day ] + values
+        end
+
         if self.class.send(:create_time_zone_conversion_attribute?, name, column_for_attribute(name))
           Time.zone.local(*values)
         else
@@ -3053,12 +3060,13 @@ module ActiveRecord #:nodoc:
 
               send(name + "=", value)
             rescue => ex
+              raise ex
               errors << AttributeAssignmentError.new("error on assignment #{values.inspect} to #{name}", ex, name)
             end
           end
         end
         unless errors.empty?
-          raise MultiparameterAssignmentErrors.new(errors), "#{errors.size} error(s) on assignment of multiparameter attributes"
+          raise MultiparameterAssignmentErrors.new(errors), "#{errors.size} error(s) on assignment of multiparameter attributes: #{errors.collect(&:to_s).to_sentence}"
         end
       end
 
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 99d7796..8011af7 100755
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -1144,6 +1144,16 @@ class BasicsTest < ActiveRecord::TestCase
     assert_equal Time.local(2004, 6, 24, 16, 24, 0), topic.written_on
   end
 
+  def test_multiparameter_attributes_on_time_with_empty_date
+    attributes = {
+      "written_on(1i)" => "", "written_on(2i)" => "", "written_on(3i)" => "",
+      "written_on(4i)" => "16", "written_on(5i)" => "24"
+    }
+    topic = Topic.find(1)
+    topic.attributes = attributes
+    assert_equal(Time.local(Date.today.year, Date.today.month, Date.today.day, 16, 24), topic.written_on)
+  end
+
   def test_multiparameter_mass_assignment_protector
     task = Task.new
     time = Time.mktime(2000, 1, 1, 1)