Django - save() update on duplicate key

Question

I have little application which allows a user to rate a video.

The user can rate only once. So I have defined the uniqueness on the model.

But he should be a

Answer 1

To update an existing rating, you actually have to have the one you want to update. If you know the object may not exist, use get_or_create:

rate, created = VideoRate.objects.get_or_create(user_id=1, video_id=1, crit_id=1)
rate.rate = 2
rate.save()

You can short-cut the process by using update():

VideoRate.objects.filter(user_id=1, video_id=1, crit_id=1).update(rate=2)

But this will silently fail if the rating does not exist - it won't create one.