Django admin causes high load for one model...

Question

In my Django admin, when I try to view/edit objects from one particular model class the memory usage and CPU rockets up and I have to restart the server. I can view the list of objects fine, but the problem comes when I click on one of the objects. Other models are fine. Working with the object in code (i.e. creating and displaying) is ok, the problem only arises when I try to view an object with the admin interface. The class isn't even particularly exotic:

class Comment(models.Model):
    user = models.ForeignKey(User)
    thing = models.ForeignKey(Thing)
    date = models.DateTimeField(auto_now_add=True)
    content = models.TextField(blank=True, null=True)
    approved = models.BooleanField(default=True)

    class Meta:
        ordering = ['-date']

Any ideas? I'm stumped. The only reason I could think of might be that the thing is quite a large object (a few kb), but as I understand it, it wouldn't get loaded until it was needed (correct?).

Answer 1

It's not really a question of how big the Thing object is, but rather of how many you have in your database. That's because for a ForeignKey, by default Django's admin gives you a drop-down list containing all the existing items. If you've got lots and lots, then Django will load them all in order to populate that list. The same is true here of User.

The best way round this is to add the offending field to the raw_id_fields in your ModelAdmin subclass. That will change the representation to a simple textfield for the id, with a pop-up lookup window.