Rails4（くらい）で has_secure_password のバリデーションをスキップしたり

user.rb

class User < ActiveRecord::Base
  has_secure_password validations: false

  validates :password,
    presence:     {if: :password_required?, on: :create},
    confirmation: {if: :password_required?}
    
  validates :password_confirmation,
    presence:     {if: :password_present?}

  before_create {
    raise 'Password digest missing on new record' if
      password_required? and password_digest.blank?
  }
  
  def password_present?
    password.present?
  end

  def password_required?
    raise 'ここに条件が来ます。'
  end
end