Django ORM how to Round an Avg result

Question

I have a model in which I use Django ORM to extract Avg of values from the table. I want to Round that Avg value, how do I do this?

See below I am extracting Avg pri

Answer 1

I needed to have both PostgreSQL and SQLite support, but also keep the ability to specify the number of digit to keep.

Build on previous answers :

class Round(Func):
    function = 'ROUND'
    arity = 2
    # Only works as the arity is 2
    arg_joiner = '::numeric, '

    def as_sqlite(self, compiler, connection, **extra_context):
        return super().as_sqlite(compiler, connection, arg_joiner=", ", **extra_context)

# Then one can use it as:
# queryset.annotate(avg_val=Round(AVG("val"), 6))

I would have prefered something cleaner like

if SQLITE:
    arg_joiner=", "
elif PGSQL:
    arg_joiner = '::numeric, '
else raise NotImplemented()

but did not find how, feel free to improve !