Django models - how to filter out duplicate values by PK after the fact?

Question

I build a list of Django model objects by making several queries. Then I want to remove any duplicates, (all of these objects are of the same type with an auto_increment int PK), but I can't use set() because they aren't hashable.

Is there a quick and easy way to do this? I'm considering using a dict instead of a list with the id as the key.

Answer 1

In general it's better to combine all your queries into a single query if possible. Ie.

q = Model.objects.filter(Q(field1=f1)|Q(field2=f2))

instead of

q1 = Models.object.filter(field1=f1)
q2 = Models.object.filter(field2=f2)

If the first query is returning duplicated Models then use distinct()

q = Model.objects.filter(Q(field1=f1)|Q(field2=f2)).distinct()

If your query really is impossible to execute with a single command, then you'll have to resort to using a dict or other technique recommended in the other answers. It might be helpful if you posted the exact query on SO and we could see if it would be possible to combine into a single query. In my experience, most queries can be done with a single queryset.