Provide a way to specify alternate option keys for validates

1 files changed, 7 insertions, 1 deletions

diff --git a/activemodel/lib/active_model/validations/validates.rb b/activemodel/lib/active_model/validations/validates.rb
index 172ca70c19..7ff42de00b 100644
--- a/activemodel/lib/active_model/validations/validates.rb
+++ b/activemodel/lib/active_model/validations/validates.rb
@@ -81,7 +81,7 @@ module ActiveModel
       #
       def validates(*attributes)
         defaults = attributes.extract_options!
-        validations = defaults.slice!(:if, :unless, :on, :allow_blank, :allow_nil)
+        validations = defaults.slice!(*_validates_default_keys)
 
         raise ArgumentError, "You need to supply at least one attribute" if attributes.empty?
         raise ArgumentError, "You need to supply at least one validation" if validations.empty?
@@ -103,6 +103,12 @@ module ActiveModel
 
     protected
 
+      # When creating custom validators, it might be useful to be able to specify
+      # additional default keys. This can be done by overwriting this method.
+      def _validates_default_keys
+        [ :if, :unless, :on, :allow_blank, :allow_nil ]
+      end
+
       def _parse_validates_options(options) #:nodoc:
         case options
         when TrueClass