Be able to pass a validator method to #validates

3 files changed, 22 insertions, 0 deletions

diff --git a/activemodel/lib/active_model/validations/with.rb b/activemodel/lib/active_model/validations/with.rb
index 200efd4eb5..16d81263a2 100644
--- a/activemodel/lib/active_model/validations/with.rb
+++ b/activemodel/lib/active_model/validations/with.rb
@@ -8,6 +8,12 @@ module ActiveModel
         end
     end
 
+    class WithValidator < EachValidator
+      def validate_each(record, attr, val)
+        record.send options[:with]
+      end
+    end
+
     module ClassMethods
       # Passes the record off to the class or classes specified and allows them
       # to add errors based on more complex conditions.
diff --git a/activemodel/test/cases/validations/with_validation_test.rb b/activemodel/test/cases/validations/with_validation_test.rb
index 6d825cd316..33efedcd7c 100644
--- a/activemodel/test/cases/validations/with_validation_test.rb
+++ b/activemodel/test/cases/validations/with_validation_test.rb
@@ -171,4 +171,16 @@ class ValidatesWithTest < ActiveModel::TestCase
     assert topic.errors[:title].empty?
     assert topic.errors[:content].empty?
   end
+
+  test "validates_with can validate with an instance method" do
+    Topic.validates :title, :with => :my_validation
+
+    topic = Topic.new :title => "foo"
+    assert topic.valid?
+    assert topic.errors[:title].empty?
+
+    topic = Topic.new
+    assert !topic.valid?
+    assert_equal ['is missing'], topic.errors[:title]
+  end
 end
diff --git a/activemodel/test/models/topic.rb b/activemodel/test/models/topic.rb
index 2f0bb95071..8d49c1dd27 100644
--- a/activemodel/test/models/topic.rb
+++ b/activemodel/test/models/topic.rb
@@ -29,4 +29,8 @@ class Topic
     self.after_validation_performed = true
   end
 
+  def my_validation
+    errors.add :title, "is missing" unless title
+  end
+
 end