Make `.validators_on` accept `:kind` option

This will filter out the validators on a particular attribute based on
its kind.

1 files changed, 12 insertions, 1 deletions

diff --git a/activemodel/lib/active_model/validations.rb b/activemodel/lib/active_model/validations.rb
index 4762f39044..5a3225a7e6 100644
--- a/activemodel/lib/active_model/validations.rb
+++ b/activemodel/lib/active_model/validations.rb
@@ -187,10 +187,21 @@ module ActiveModel
       #   #       #<ActiveModel::Validations::PresenceValidator:0x007fe604914e60 @attributes=[:name], @options={}>,
       #   #       #<ActiveModel::Validations::InclusionValidator:0x007fe603bb8780 @attributes=[:age], @options={:in=>0..99}>
       #   #    ]
+      #
+      # You can also pass a +:kind+ option to filter the validators based on their kind.
+      #
+      #   Person.validators_on(:name, kind: :presence)
+      #   # => [#<ActiveModel::Validations::PresenceValidator:0x007fe604914e60 @attributes=[:name], @options={}>]
       def validators_on(*attributes)
+        options = attributes.extract_options!
+
         attributes.map do |attribute|
           _validators[attribute.to_sym]
-        end.flatten
+        end.flatten.tap do |validators|
+          if options[:kind]
+            validators.select! { |validator| validator.kind == options[:kind] }
+          end
+        end
       end
 
       # Returns +true+ if +attribute+ is an attribute method, +false+ otherwise.