I have looked through the Ruby on Rails guides and I can't seem to figure out how to prevent someone from deleting a Parent record if it has Children. For example. If my database has CUSTOMERS and each customer can have multiple ORDERS, I want to prevent someone from deleting a customer if it has any orders in the database. They should only be able to delete a customer if it has no orders.
Is there a way when defining the association between models to enforce this behavior?
One possibility would be to avoid providing your users a link to deletion in this scenario.
link_to_unless [email protected]?
Another way would be to handle this in your controller:
if [email protected]?
flash[:notice] = "Cannot delete a customer with orders"
render :action => :some_action
end
Or, as Joe suggests, before_filters could work well here and would probably be a much more DRY way of doing this, especially if you want this type of behavior for more models than just Customer.
You could do this in a callback:
class Customer < ActiveRecord::Base
has_many :orders
before_destroy :check_for_orders
private
def check_for_orders
if orders.count > 0
errors.add_to_base("cannot delete customer while orders exist")
return false
end
end
end