1 files changed, 23 insertions, 7 deletions
diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index f90030641d..6aa0d2a16f 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -213,13 +213,7 @@ module ActiveModel
     # If +message+ is a symbol, it will be translated using the appropriate scope (see +translate_error+).
     # 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
-
-      if message.is_a?(Symbol)
-        message = generate_message(attribute, message, options.except(*CALLBACKS_OPTIONS))
-      elsif message.is_a?(Proc)
-        message = message.call
-      end
+      message = normalize_message(attribute, message, options)
       if options[:strict]
         raise ActiveModel::StrictValidationFailed,  message
       end
@@ -244,6 +238,15 @@ module ActiveModel
       end
     end
 
+    # Returns true if an error on the attribute with the given message is present, false otherwise.
+    # +message+ is treated the same as for +add+.
+    #   p.errors.add :name, :blank
+    #   p.errors.added? :name, :blank # => true
+    def added?(attribute, message = nil, options = {})
+      message = normalize_message(attribute, message, options)
+      self[attribute].include? message
+    end
+
     # Returns all the full error messages in an array.
     #
     #   class Company
@@ -329,6 +332,19 @@ module ActiveModel
 
       I18n.translate(key, options)
     end
+
+  private
+    def normalize_message(attribute, message, options)
+      message ||= :invalid
+
+      if message.is_a?(Symbol)
+        generate_message(attribute, message, options.except(*CALLBACKS_OPTIONS))
+      elsif message.is_a?(Proc)
+        message.call
+      else
+        message
+      end
+    end
   end
 
   class StrictValidationFailed < StandardError