crystal-lang/crystal

Hey all, I'm trying to make crystal app with Kemal, Granite ORM on postgres. My question is I created one model that needs to update password to encrypted one. But on the build, It's giving error as...

instance variable '@password' of User must be (String | Nil), not Crypto::Bcrypt::Password

require "granite_orm/adapter/pg"
require "crypto/bcrypt/password"
require "logger"
require "kemal"

log = Logger.new(STDOUT)
log.level = Logger::WARN

class User < Granite::ORM::Base
  adapter pg

  before_save :prepare_data

  field email : String
  field password : String
  timestamps

  def prepare_data
    if password = @password
      log("#{password}")
      @password = Crypto::Bcrypt::Password.create(password)
      log("#{@password} | #{password}")
    end
  end
end

module Crystal::Chat
  get "/" do
    user = User.new
    user.email = "test@test.com"
    user.password = "pass1234"
    user.save

    "Hello World! #{VERSION}"
  end

  Kemal.run
end