Add `ActiveModel::Validations::AbsenceValidator`, a validator to check the absence of attributes.

Add `ActiveModel::Errors#add_on_present` method. Adds error messages to present attributes.

1 files changed, 19 insertions, 0 deletions

diff --git a/activemodel/CHANGELOG.md b/activemodel/CHANGELOG.md
index ac71b9d1dc..014500fa28 100644
--- a/activemodel/CHANGELOG.md
+++ b/activemodel/CHANGELOG.md
@@ -1,4 +1,23 @@
 ## Rails 4.0.0 (unreleased) ##
+*   Add `ActiveModel::Validations::AbsenceValidator`, a validator to check the
+    absence of attributes.
+
+        class Person < ActiveRecord::Base
+          validates_absence_of :first_name
+        end
+
+        person = Person.new
+        person.first_name = "John"
+        person.valid?
+        => false
+        # first_name must be blank
+
+    * Roberto Vasquez Angel*
+
+*   Added `ActiveModel::Errors#add_on_present` method. Adds error messages to
+    present attributes.
+
+    *Roberto Vasquez Angel*
 
 *   `[attribute]_changed?` now returns `false` after a call to `reset_[attribute]!`