5. How to perform truncate like operation using Django ORM?

Truncate statement in SQL is meant to empty a table for future use. Though Django doesn’t provide a builtin to truncate a table, but still similar result can be achived using delete() method. For example:

>>> Category.objects.all().count()
7
>>> Category.objects.all().delete()
(7, {'entity.Category': 7})
>>> Category.objects.all().count()
0

This works, but this uses DELETE FROM ... SQL statement. If you have a large number of records, this can be quite slow. You can add a classmethod to Category if you want to enable truncate.

class Category(models.Model):
    # ...

    @classmethod
    def truncate(cls):
        with connection.cursor() as cursor:
            cursor.execute('TRUNCATE TABLE "{0}" CASCADE'.format(cls._meta.db_table))

Then you can call Category.truncate() to a real database truncate.