Django - deleting an object without deleting related objects

Question

I have two models:

class Client(models.Model): some_field = models.CharField() class Ticket(models.Model): client = models.ForeignKey(Client) 

Ticket FOREVER is on my system, but I want users to be able to delete clients they no longer want. Currently, it will delete all tickets created by Client .

• Is this a bad idea (architecturally speaking) and should I just mark them as not_needed or something instead?
• If this is not a bad idea, what is the best way to do this by staying DRY. I don't want to override delete() for every model that does this, but will if I need to (which is the best way to do this if this is the only way).

Answer 1

So, this question is very old, but in case someone runs it (like me): starting with Django 1.3, you can use the on_delete parameter for ForeignKey models, as described here .

Answer 2

The django.contrib.auth module must deal with the same problem in the User model. Their solution is to:

 class User(models.Model): # ... is_active = models.BooleanField(default=True) # ... 

So the “removal” of a User simply sets is_active to False . Everything that works with User needs to check is_active .

For the record, I think that uninstalling Client in this case is a Bad idea .

But for the sake of argument, if you delete Client , then the associated Ticket must first become without a client. Change the model for Ticket to:

 class Ticket(models.Model): client = models.ForeignKey(Client, null=True, blank=True, related_name='tickets') 

Then, to remove a Client , do:

 for ticket in clientToDelete.tickets: ticket.client = None ticket.save() clientToDelete.delete() 

You can put this code in the Client delete method, but it will be skipped if you delete the array (i.e. based on QuerySet) of Client s.

Answer 3

Personally, I think this is a bad idea (you would have records of orphan tickets). I would simply mark these clients as "not_needed" or "deleted". You also get the added benefit of being able to “delete” these clients later.