[Python] Writing a tuple search with Django ORM

I'm trying to write a search based on tuples with the Django ORM syntax.

The final sql statement should look something like:

SELECT * FROM mytable WHERE (field_a,field_b) IN ((1,2),(3,4));


I know I can achieve this in django using the extra keyword:

MyModel.objects.extra(
where=["(field_a, field_b) IN %s"],
params=[((1,2),(3,4))]
)


but the "extra" keyword will be deprecated at some point in django so I'd like a pure ORM/django solution.

Searching the web, I found https://code.djangoproject.com/ticket/33015 and the comment from Simon Charette, something like the snippet below could be OK, but I can't get it to work.

from django.db.models import Func, lookups

class ExpressionTuple(Func):
template = '(%(expressions)s)'
arg_joiner = ","


MyModel.objects.filter(lookups.In(
ExpressionTuple('field_a', 'field_b'),
((1,2),(3,4)),
))


I'm using Django 3.2 but I don't expect Django 4.x to do a big difference here. My db backend is posgresql in case it matters.

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