Use activerecord.errors.format as in Rails 2.3.5.

activemodel/lib/active_model/errors.rb

@@ -105,11 +105,11 @@ def full_messages
         else
           attr_name = attribute.to_s.gsub('.', '_').humanize
           attr_name = @base.class.human_attribute_name(attribute, :default => attr_name)
-          options = { :default => ' ', :scope => @base.class.i18n_scope }
-          prefix = attr_name + I18n.t(:"errors.format.separator", options)
+          options = { :default => "{{attribute}} {{message}}", :attribute => attr_name,
+                      :scope => @base.class.i18n_scope }
 
           messages.each do |m|
-            full_messages <<  "#{prefix}#{m}"
+            full_messages << I18n.t(:"errors.format", options.merge(:message => m))
           end
         end
       end

activemodel/lib/active_model/locale/en.yml

@@ -1,6 +1,9 @@
 en:
   activemodel:
     errors:
+      # model.errors.full_messages format.
+      format: "{{attribute}} {{message}}"
+
       # The values :model, :attribute and :value are always available for interpolation
       # The value :count is available when applicable. Can be used for pluralization.
       messages:

activemodel/test/cases/validations/i18n_validation_test.rb

@@ -61,6 +61,12 @@ def test_errors_full_messages_translates_human_attribute_name_for_model_attribut
     @person.errors.full_messages
   end
 
+  def test_errors_full_messages_uses_format
+    I18n.backend.store_translations('en', :activemodel => {:errors => {:format => "Field {{attribute}} {{message}}"}})
+    @person.errors.add('name', 'empty')
+    assert_equal ["Field Name empty"], @person.errors.full_messages
+  end
+
   # ActiveRecord::Validations
   # validates_confirmation_of w/ mocha
   def test_validates_confirmation_of_generates_message

activerecord/lib/active_record/locale/en.yml

@@ -1,6 +1,9 @@
 en:
   activerecord:
     errors:
+      # model.errors.full_messages format.
+      format: "{{attribute}} {{message}}"
+
       # The values :model, :attribute and :value are always available for interpolation
       # The value :count is available when applicable. Can be used for pluralization.
       messages: