gistfile1.txt

diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index ed82c6b..f7851df 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -179,11 +179,14 @@ module ActiveModel
     # If +message+ is a proc, it will be called, allowing for things like <tt>Time.now</tt> to be used within an error.
     def add(attribute, message = nil, options = {})
       message ||= :invalid
+      options[:message] ||= message
 
-      if message.is_a?(Symbol)
-        message = generate_message(attribute, message, options.except(*CALLBACKS_OPTIONS))
-      elsif message.is_a?(Proc)
-        message = message.call
+      [ :message, :full_message ].each do |key|
+        if options[key].is_a?(Symbol)
+          message = generate_message(attribute, message, options.except(*CALLBACKS_OPTIONS), key)
+        elsif options[key].is_a?(Proc)
+          message = message.call
+        end
       end
 
       self[attribute] << message
@@ -278,25 +281,19 @@ module ActiveModel
     # <li><tt>errors.attributes.title.blank</tt></li>
     # <li><tt>errors.messages.blank</tt></li>
     # </ol>
-    def generate_message(attribute, type = :invalid, options = {})
-      type = options.delete(:message) if options[:message].is_a?(Symbol)
-
+    def generate_message(attribute, type = :invalid, options = {}, key)
+      type = options.delete(key) if options[key].is_a?(Symbol)
 
+      # TODO: This will lookup in the same place for both full_messages and messages
       defaults = @base.class.lookup_ancestors.map do |klass|
         [ :"#{@base.class.i18n_scope}.errors.models.#{klass.model_name.underscore}.attributes.#{attribute}.#{type}",
           :"#{@base.class.i18n_scope}.errors.models.#{klass.model_name.underscore}.#{type}" ]
       end
 
-      defaults << options.delete(:message)
-      defaults << :"#{@base.class.i18n_scope}.errors.messages.#{type}"
+      defaults << options[key]
+      defaults << :"#{@base.class.i18n_scope}.errors.#{key}s.#{type}"
       defaults << :"errors.attributes.#{attribute}.#{type}"
-      defaults << :"errors.messages.#{type}"
+      defaults << :"errors.#{key}s.#{type}"
 
       defaults.compact!
       defaults.flatten!
@@ -309,7 +306,7 @@ module ActiveModel
         :model => @base.class.model_name.human,
         :attribute => @base.class.human_attribute_name(attribute),
         :value => value
-      }.merge(options)
+      }.merge(options.except(:message, :full_message))
 
       I18n.translate(key, options)
     end

It's hard to understand just looking at the patch. I will need to apply it when I get home to understand it better. For instance, at first, it seems that the last changed line should read merge! instead of merge, but it is hard to know without the entire context. I'll take a closer look at it when I get home, but surely full_errors.messages looks strange. I'll think more about this tonight...