Rails - validation inside decorator - ruby-on-rails

Question

I'm struggling with some kind of issue. I have a rails model (mongoid).
class User
include Mongoid::Document
include ActiveModel::SecurePassword
validate :password_presence,
:password_confirmation_match,
:email_presence,
field :email
field :password_digest
def password_presence
end
def email_presence
end
def password_confirmation_match
end
end
My goal is to call validations depends on which decorator I will use. Let's say I've got two decorators:
class PasswordDecorator < Draper::Decorator
def initialize(user)
#user = user
end
end
def RegistraionDecorator < Draper::Decorator
def initialize(user)
#user = user
end
end
So now when I create/save/update my user object inside RegistraionDecorator I would like to perform all validation methods.
RegistraionDecorator.new(User.new(attrbiutes))
But when I will do it inside PasswordDecorator I want to call for example only password_presence method.
PasswordDecorator.new(User.first)
When I move validations to decorator it won't work cuz its different class than my model.
How can I achieve that?

Answer 1

Try to use a Form Object pattern instead.
Here is an example (from a real project) of how it could be done with reform.
class PromocodesController < ApplicationController
def new
#form = PromocodeForm.new(Promocode.new)
end
def create
#form = PromocodeForm.new(Promocode.new)
if #form.validate(promo_params)
Promocode.create!(promo_params)
redirect_to promocodes_path
else
render :edit
end
end
private
def promo_params
params.require(:promocode).
permit(:token, :promo_type, :expires_at, :usage_limit, :reusable)
end
end
class PromocodeForm < Reform::Form
model :promocode
property :token
property :promo_type
property :expires_at
property :usage_limit
property :reusable
validates_presence_of :token, :promo_type, :expires_at, :usage_limit, :reusable
validates_uniqueness_of :token
validates :usage_limit, numericality: { greater_or_equal_to: -1 }
validates :promo_type, inclusion: { in: Promocode::TYPES }
end
Bonus: The model does not trigger validations and much easy to use in tests.