Queryset.query not pickled correctly when saving PickledObjectField since Django 3.0

[flokain]

trying to pickle a Query object.
it seems like the default values is not being serialized:

DB is postgres 10.1
django 3.0.3
python 3.7.4

eligible_team_query = PickledObjectField(default=Team.objects.all().query)

  File "/usr/local/lib/python3.7/site-packages/django/db/backends/utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
psycopg2.errors.SyntaxError: subquery must return only one column
LINE 1: ...query", "eligible_team_query") VALUES ('u17', '', (SELECT "p...

Originally posted by @flokain in #47 (comment)

[charettes]

I'm afraid there's very little we'll be able to do as we want to keep allowing the usage of expressions in Field.default. In other words special casing expressions in PickledObjectField.get_default would prevent stuff like default=F('other_pickled_field'). Django 3.0 just happened to make django.db.models.sql.Query an expression which is what causing your crash here.

I assume the following works just fine?

from picklefield.fields import dbsafe_encode 

def default_eligible_team_query(self):
    return dbsafe_encode(Team.objects.all().query)

eligible_team_query = PickledObjectField(default=default_eligible_team_query)

[flokain]

yes this works. thank you!

[charettes]

Alright I'll close the issue then as there's little django-picklefield can do about passing ORM internal objects to the ORM.