For Rails < 2.3 need to probe for empty? method to distinguish a collection proxy from other relations.

Author: aepstein

lib/declarative_authorization/authorization.rb

@@ -512,7 +512,8 @@ def validate? (attr_validator, object = nil, hash = nil)
       object ||= attr_validator.object
       return false unless object
 
-      if Authorization.is_a_association_proxy?(object)
+      if ( Authorization.is_a_association_proxy?(object) &&
+           object.respond_to?(:empty?) )
         return false if object.empty?
         object.each do |member|
           return true if validate?(attr_validator, member, hash)