Store translated model to/from more than one database fails

[baudhuina]

Hello,

My model is:

class InstrumentFamily(TranslatableModel):
    primary_key = True
    translations = TranslatedFields(
        label=CharNullField(_('Label'), max_length=100, unique=False, null=True,)

I have 2 database aliases 'default' and 'test' and my database router directs my model to 'test'.
I insert models in both databases by doing this:

fam = InstrumentFamily(code=TEST_CODE)
with switch_language(fam, 'en'):
    fam.label = "test_family_test EN"
with switch_language(fam, 'fr'):
    fam.label = "test_family_test FR"
fam.save()

which stores the object and its translations in database 'test', or by doing this:

fam = InstrumentFamily(code="TEST_FAM")
with switch_language(fam, 'en'):
    fam.label = "test_family_default_EN"
with switch_language(fam, 'fr'):
    fam.label = "test_family_default_FR"
fam.save(using='default')

which saves the object and its translations to database 'default'. So far, so good.

But when accessing the object previously saved in 'default' by doing this (after properly clearing all caches to force a database read):

fam = InstrumentFamily.objects.using('default').get(code=TEST_CODE)
print(f"  label: {fam.label}")

django-parler properly retrieves the object from database 'default', but looks for the translation from database 'test' ! (SQL trace below, see the very end of each line):

SELECT "orchestra_instrumentfamily"."id", "orchestra_instrumentfamily"."code" FROM "orchestra_instrumentfamily" WHERE "orchestra_instrumentfamily"."code" = 'TEST_FAM' LIMIT 21; args=('TEST_FAM',); alias=default
SELECT "orchestra_instrumentfamily_translation"."id", "orchestra_instrumentfamily_translation"."language_code", "orchestra_instrumentfamily_translation"."label", "orchestra_instrumentfamily_translation"."master_id" FROM "orchestra_instrumentfamily_translation" WHERE ("orchestra_instrumentfamily_translation"."master_id" = 34 AND "orchestra_instrumentfamily_translation"."language_code" = 'en') LIMIT 21; args=(34, 'en'); alias=test

This problem was originally reported on StackOverflow ([https://stackoverflow.com/questions/73792025/django-parler-how-to-store-and-retrieve-a-translated-model-to-from-more-than-on/74730082#74730082]) where the original author of django-parler (vdboor) confirmed this is likely to be a bug : django-parler doesn't pass the "using()" information to its internal queries that retrieve translation model data.