Django: check whether an object already exists before adding

Question

How do I check whether an object already exists, and only add it if it does not already exist?

Here's the code - I don't want to add the follow_role twice in the database if it already exists. How do I check first? Use get() maybe - but then will Django complain if get() doesn't return anything?

current_user = request.user follow_role = UserToUserRole(from_user=current_user, to_user=user, role='follow') follow_role.save() 

Answer 1

There's a helper function for this idiom called 'get_or_create' on your model manager:

role, created = UserToUserRole.objects.get_or_create(     from_user=current_user, to_user=user, role='follow') 

It returns a tuple of (model, bool) where 'model' is the object you're interested in and 'bool' tells you whether it had to be created or not.