gistfile1.diff

diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index e548aa9..61164d9 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -277,8 +277,16 @@ module ActiveModel
       return message if attribute == :base
       attr_name = attribute.to_s.gsub('.', '_').humanize
       attr_name = @base.class.human_attribute_name(attribute, :default => attr_name)
+      defaults = []
+      if @base.class.respond_to?(:i18n_scope)
+        @base.class.lookup_ancestors.map do |klass|
+          defaults << :"#{@base.class.i18n_scope}.errors.models.#{klass.model_name.i18n_key}.attributes.#{attribute}.format"
+          defaults << :"#{@base.class.i18n_scope}.errors.models.#{klass.model_name.i18n_key}.format"
+        end
+      end
+      defaults << "%{attribute} %{message}"
       I18n.t(:"errors.format", {
-        :default   => "%{attribute} %{message}",
+        :default   => defaults,
         :attribute => attr_name,
         :message   => message
       })
diff --git a/activemodel/test/cases/validations/i18n_validation_test.rb b/activemodel/test/cases/validations/i18n_validation_test.rb
index e9f0e43..a43b30d 100644
--- a/activemodel/test/cases/validations/i18n_validation_test.rb
+++ b/activemodel/test/cases/validations/i18n_validation_test.rb
@@ -55,12 +55,25 @@ class I18nValidationTest < ActiveModel::TestCase
     assert_equal ["Person's name not found"], @person.errors.full_messages
   end
 
-  def test_errors_full_messages_uses_format
+  def test_errors_full_messages_uses_default_format
     I18n.backend.store_translations('en', :errors => {:format => "Field %{attribute} %{message}"})
     @person.errors.add('name', 'empty')
     assert_equal ["Field Name empty"], @person.errors.full_messages
   end
 
+  def test_errors_full_messages_uses_custom_field_level_format
+    I18n.backend.store_translations('en', :activemodel => {:errors => {:models => {:person => {:format => "ooga booga %{attribute} %{message}"}}}})
+    I18n.backend.store_translations('en', :activemodel => {:errors => {:models => {:person => {:attributes => {:name => {:format => "very custom %{attribute} %{message}"}}}}}})
+    @person.errors.add('name', 'empty')
+    assert_equal ["very custom Name empty"], @person.errors.full_messages
+  end
+
+  def test_errors_full_messages_uses_custom_model_level_format
+    I18n.backend.store_translations('en', :activemodel => {:errors => {:models => {:person => {:format => "ooga booga %{attribute} %{message}"}}}})
+    @person.errors.add('name', 'empty')
+    assert_equal ["ooga booga Name empty"], @person.errors.full_messages
+  end
+
   # ActiveModel::Validations
 
   # A set of common cases for ActiveModel::Validations message generation that