Question

I have an Assignment class which belongs to both a User class and a Role class. It stores three values – a reference to the User it belongs to, a reference to the Role it belongs to, and a string value indicating the name of the User who create the Assignment instance.

class Assignment < ActiveRecord::Base
  include ActiveModel::Validations

  belongs_to :user
  belongs_to :role  

  attr_accessible :user, :role, :assigned_by_user

  ...

In my model validation, I would like to perform a check to make sure that the assigned_by_user attribute does match the name of a valid user. However, I can’t seem to access the User.find(…) method within the Assignment model.

How would I achieve this functionality?

Answer 1

Add a “Check User” module to your lib folder (check_user.rb). Then in that file

 module CheckUser

 def search_user
  user = User.find_by_name(self.assigned_by_user)
  unless item.nil?
    errors.add(:name_found, "This username has already been taken")
  end
 end

Then in your Assignment model

 class Assignment < ActiveRecord::Base
  include CheckUser
  validate :search_user