ActiveRecord - Partial model validation

partial_validation.rb

###
# DISCLAIMER - USE AT YOUR OWN RISK
# I'm using it with rails from version 4.2.4 to 4.2.6
#
# This file can be pasted in app/models/concerns
#
# This module needs to be included in the model to enable partial validation.
# It is designed to make partial validation transparent for the model.
# The controller is ... in control ;)
#
# Usage:
# 
# 1. include the module in the model to enable partial validation
# 
# class MyModel < ActiveRecord::Base
#   include Concerns::PartialValidation
#   # write validations as usual
# end
#
# 2. perform partial validation in the controller
# 
# class MyModelController < ApplicationController
#   # This action performs a partial update, with partial validation
#   # It will validate updated parameters only.
#   def update
#     my_model= MyModel.find(params[:id])
#     my_model.assign_attributes(params[:my_model])
#     my_model.save(partial_validation: params[:my_model].keys)
#   end
# end
#
module Concerns
  module PartialValidation
    extend ActiveSupport::Concern

    def valid?(context = nil, partial_validation = nil)
      context ||= (new_record? ? :create : :update)
      super(context)
      if partial_validation
        (errors.keys - partial_validation).each do |validation_to_skip|
          errors.delete(validation_to_skip)
        end
      end
      errors.empty?
    end

    def perform_validations(options={}) # :nodoc:
      options[:validate] == false || valid?(options[:context], options[:partial_validation].try!(:map, &:to_sym))
    end
  end
end