CODEWITHSUNDEEP
djangodjango-parler
Alain Baudhuin
Alain Baudhuin

Reputation: 11

Django-parler: how to store and retrieve a translated model to/from more than one database?

EDIT 08/2023: This issue has been thoroughly investigated, and is fixed by pull-request #340.

I'm a big fan of Django-parler, but I've run into a problem when storing a translated model in two different databases.

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

I'm obviously missing something big... What am I supposed to do to have the 'using("default")' information propagated to the second query? I couldn't find anything in the documentation about storing TranslatableModels in more than one database. Am I trying to achieve something parler does not support?

Thanks in advance for enlightening me!

Upvotes: 1

Views: 376

Answers (1)

vdboor
vdboor

Reputation: 22526

This looks like a bug in django-parler. It doesn't pass the using information to its internal queries that retrieve translation model data. You can file a bit in the GitHub repository so this can be addressed.

A workaround would be to implement a database-router that enforces using a particular database for this model.

Upvotes: 0

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