From 923bdff54d7f2e31bdfffc16e7b2f1ec25f63583 Mon Sep 17 00:00:00 2001
From: Prem Sichanugrist <s@sikachu.com>
Date: Thu, 18 Feb 2010 22:28:48 +0700
Subject: [PATCH] Add validators reflection so you can do 'Person.validators' and 'Person.validators_on(:name)'.

---
 activemodel/lib/active_model/validations.rb        |   33 ++++++++++++++++++--
 .../test/cases/validations/with_validation_test.rb |    1 +
 activemodel/test/cases/validations_test.rb         |   29 +++++++++++++++++
 3 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/activemodel/lib/active_model/validations.rb b/activemodel/lib/active_model/validations.rb
index 03733a9..54e13b8 100644
--- a/activemodel/lib/active_model/validations.rb
+++ b/activemodel/lib/active_model/validations.rb
@@ -1,4 +1,5 @@
 require 'active_support/core_ext/array/extract_options'
+require 'active_support/core_ext/class/attribute'
 require 'active_support/core_ext/hash/keys'
 require 'active_model/errors'
 
@@ -45,6 +46,9 @@ module ActiveModel
     included do
       extend ActiveModel::Translation
       define_callbacks :validate, :scope => :name
+
+      class_attribute :_validators
+      self._validators = Hash.new { |h,k| h[k] = [] }
     end
 
     module ClassMethods
@@ -115,11 +119,34 @@ module ActiveModel
           options[:if] = Array(options[:if])
           options[:if] << "@_on_validate == :#{options[:on]}"
         end
+
+        validator = args.first
+        if validator.respond_to?(:validate)
+          if validator.respond_to?(:attributes) and !validator.attributes.empty?
+            validator.attributes.each do |attribute|
+              _validators[attribute.to_sym] << validator
+            end
+          else
+            _validators[nil] << validator
+          end
+        end
+
         set_callback(:validate, *args, &block)
       end
-    
-      private
-    
+
+      # List all validators that being used to validate the model using +validates_with+
+      # method.
+      def validators
+        _validators.values.flatten.uniq
+      end
+
+      # List all validators that being used to validate a specific attribute.
+      def validators_on_attribute(attribute)
+        _validators[attribute.to_sym]
+      end
+
+    private
+
       def _merge_attributes(attr_names)
         options = attr_names.extract_options!
         options.merge(:attributes => attr_names)
diff --git a/activemodel/test/cases/validations/with_validation_test.rb b/activemodel/test/cases/validations/with_validation_test.rb
index 66b072e..7b4d77c 100644
--- a/activemodel/test/cases/validations/with_validation_test.rb
+++ b/activemodel/test/cases/validations/with_validation_test.rb
@@ -9,6 +9,7 @@ class ValidatesWithTest < ActiveRecord::TestCase
 
   def teardown
     Topic.reset_callbacks(:validate)
+    Topic.instance_variable_set(:@_validators, nil)
   end
 
   ERROR_MESSAGE = "Validation error from validator"
diff --git a/activemodel/test/cases/validations_test.rb b/activemodel/test/cases/validations_test.rb
index eb100d1..18f3254 100644
--- a/activemodel/test/cases/validations_test.rb
+++ b/activemodel/test/cases/validations_test.rb
@@ -9,6 +9,10 @@ require 'models/custom_reader'
 
 class ValidationsTest < ActiveModel::TestCase
   include ActiveModel::TestsDatabase
+  
+  def setup
+    Topic._validators = Hash.new { |h,k| h[k] = [] }
+  end
 
   # Most of the tests mess with the validations of Topic, so lets repair it all the time.
   # Other classes we mess with will be dealt with in the specific tests
@@ -220,4 +224,29 @@ class ValidationsTest < ActiveModel::TestCase
     assert !t.valid?
     assert ["NO BLANKS HERE"], t.errors[:title]
   end
+
+  def test_list_of_validators_for_model
+    Topic.validates_presence_of :title
+    Topic.validates_length_of :title, :minimum => 2
+
+    assert_equal 2, Topic.validators.count
+    assert Topic.validators.map(&:class).include? ActiveModel::Validations::PresenceValidator
+    assert Topic.validators.map(&:class).include? ActiveModel::Validations::LengthValidator
+  end
+
+  def test_list_of_validators_on_an_attribute
+    Topic.validates_presence_of :title, :content
+    Topic.validates_length_of :title, :minimum => 2
+
+    assert_equal 2, Topic.validators_on_attribute(:title).count
+    assert Topic.validators_on_attribute(:title).map(&:class).include? ActiveModel::Validations::PresenceValidator
+    assert Topic.validators_on_attribute(:title).map(&:class).include? ActiveModel::Validations::LengthValidator
+    assert_equal 1, Topic.validators_on_attribute(:content).count
+    assert Topic.validators_on_attribute(:content).map(&:class).include? ActiveModel::Validations::PresenceValidator
+  end
+
+  def test_accessing_instance_of_validator_on_an_attribute
+    Topic.validates_length_of :title, :minimum => 10
+    assert_equal 10, Topic.validators_on_attribute(:title).first.options[:minimum]
+  end
 end
-- 
1.6.4.2