prefetch causes fields to be added in dirty_fields

[navolotsky]

prefetch causes fields related to prefetched models to be added in dirty_fields.

Could you say why this is so? Is it not possible to make another implementation?

Thanks so much for the answer and excellent ORM.

[navolotsky]

@coleifer Please check it. I got this behavior again on Peewee 3.13.3, Python 3.8.2 (tags/v3.8.2:7b3ab59, Feb 25 2020, 23:03:10) [MSC v.1916 64 bit (AMD64)] on win32.

[coleifer]

The regression test is passing fine for me. If you add a failing test, I will look into this again.

[navolotsky]

from peewee import CharField, ForeignKeyField, Model, SqliteDatabase

database = SqliteDatabase(":memory:")


class A(Model):
    class Meta:
        database = database
        only_save_dirty = True
    some_str = CharField()


class B(Model):
    class Meta:
        database = database
        only_save_dirty = True
    another_str = CharField()
    a_instance = ForeignKeyField(model=A)


if __name__ == "__main__":
    database.create_tables(models=[A, B])
    a = A.create(some_str='s1')
    B.create(another_str='s2', a_instance=a)
    b1 = B.select().where(B.another_str == 's2').execute()[0]
    print(f"Without `prefetch`, dirty fields: {b1.dirty_fields}")
    b2 = B.select().where(B.another_str == 's2').prefetch(A)[0]
    print(f"With `prefetch`, dirty fields: {b2.dirty_fields}")

[coleifer]

OP DELIVERS. Thank you!

[coleifer]

Hey - I think I see the problem. There's absolutely no reason to use prefetch when going from a child-model to a parent-model, as SQL already handles that. Just do:

query = B.select(B, A).join(A).where(B.another_str == 's2')