Django equivalent of SQL REPLACE

Question

Is there a Django ORM best practice for this SQL:

REPLACE app_model SET field_1 = 'some val', field_2 = 'some val';

Assumption: field_1 or field_2 would have a unique key on them (or in my case on both), otherwise this would always evaluate to an INSERT.

Edit:

My best personal answer right now is this, but it's 2-3 queries where 1 should be possible:

    from django.core.exceptions import ValidationError
    try:
        Model(field_1='some val',field_2='some val').validate_unique()
        Model(field_1='some val',field_2='some val',extra_field='some val').save()
    except ValidationError:
        Model.objects.filter(field_1='some val',field_2='some val').update(extra_field='some val')