Question

What is the best way, to check that a model relationship is in use in another model to prevent it from being destroyed thus creating an orphan.

Example: I have a Ticket and TicketStatus models. TicketStatus belongs to Ticket. Ticket has_many TicketStatuses.

I should not be able to delete a TicketStatus if it is already assigned to a Ticket. I would like an error message as well.

Answer 1

Easiest ways a callback:

class TicketStatus < ActiveRecord::Base
  belongs_to :ticket
  before_destroy :check_ticket

  private

  def check_ticket
    if ticket != nil
      errors.add_to_base("cannot delete ticket status that has a ticket")
      return false
    end
  end
end

This prevents it and gives you an error.

Hope this helps!