soft_validations.rb

require "ostruct"
require "active_support/concern"
require "active_model/validations"
require "active_model/errors"

# Soft validations are based on ActiveModel::Validations but don't
# block saving a record.
#
#   class Person < ActiveRecord::Base
#     include SoftValidations
#     validates_softly :name, format: /^[A-Z]/
#   end
#
#   person = Person.new(name: "fred")
#   person.valid?                       # => true
#   person.complete?                    # => false
#   person.warnings.full_message        # ["Name is invalid"]
#   person.save                         # => true
module SoftValidations
  extend ActiveSupport::Concern

  included do |other|
    @soft = Class.new(OpenStruct) do
      include ActiveModel::Validations

      def self.name
        @parent.name
      end

      def self.i18n_scope
        @parent.i18n_scope
      end
    end

    @soft.instance_variable_set("@parent", other)
  end

  module ClassMethods
    # Like ActiveModel::Validations#validates.
    def validates_softly(*args, &block)
      @soft.validates(*args, &block)
    end

    def soft_class
      @soft
    end
  end

  # Run the soft validations on the object and return false when any
  # of them fail.  Failure are added to the warnings collection.
  def complete?
    obj = self.class.soft_class.new(attributes)
    obj.valid?.tap do
      @warnings = obj.errors
    end
  end

  # Returns a collection of warnings as an instance of
  # ActiveModel::Errors.  This collection is populated by the
  # complete? method.
  def warnings
    @warnings || ActiveModel::Errors.new(self.class.soft_class.new)
  end
end