Django how to select NULL?

Question

Django

There is a table of categories, it has a parent_id field, how to make a selection of values ​​\u200b\u200bfor which the parent_id = NULL field. Now it gives an error

Answer 1

You can use the filter operator isnull
Category.objects.filter(parent_id__isnull=True)

Answer 2

Use None in the filter