cannot unpack non-iterable NoneType object with SOFT_DELETE_CASCADE

[hamidrabedi]

I have a parent child model and i want if the parent object got deleted all the children get deleted too (safe delete in my case):

class Review(SafeDeleteModel):
    _safedelete_policy = SOFT_DELETE_CASCADE
    parent = models.ForeignKey(
        'self',
        verbose_name=_("Parent"),
        related_name="children",
        on_delete=models.CASCADE,
        null=True,
        blank=True
    )

and if i delete the parent object this error will be raised:
cannot unpack non-iterable NoneType object

[Gagaro]

I just added a test with your model which works: 6cdd3e8

Are you using the last version of safedelete? Do you overwrite the delete method?

[razdva0]

I got the same error on macbook air m1
1.3.2 version

[sazzouz]

Same issue 1.3.2, haven't overwritten any methods, occurring when using the SOFT_DELETE_CASCADE policy. Could it be to do with handling cascaded soft deletions when there are no related objects?

[hamidrabedi]

@Gagaro No, it seems like soft delete has problems with children-parent models, also has with django-mptt for tree models. related issue in django-mptt repo:
django-mptt/django-mptt#745

[Gagaro]

I made a test that passed without issue. Are you using your model like that or do you have any idea how to reproduce it?

6cdd3e8#diff-985ae0f484f9a15bfb9b8e016c13075eb6896094ff89516544436dce6c63c4feR297

[hamidrabedi]

@Gagaro Try deleting from django admin.

[razdva0]

My friend overwritten delete method without return like this:
def delete(self, force_policy=None, **kwargs): super().delete(force_policy, **kwargs)
everything is ok with return

[elihuihms]

My friend overwritten delete method without return like this: def delete(self, force_policy=None, **kwargs): super().delete(force_policy, **kwargs) everything is ok with return

To expand on @razdva0 answer, I had a model with an overridden delete() method that did not return the tuple returned by SafeDeleteModel.delete(); that's what generated this error. When I captured and returned the tuple the error went away.

[Gagaro]

Thanks for the feedbacks. @hamidrabedi , do you have a delete method which does not return anything?

[hamidrabedi]

@Gagaro Yes i do have a delete method, but it calls the super method and returns the result properly:

    def delete(self, *args, **kwargs):
        """
        This method calls the superclass's delete()
        method with the given parameters, and then invalidates
        the cache for the query set's model.
        """
        result = super().delete(**kwargs)
        self.invalidate_cache()
        return result

[Gagaro]

Do you have more parent classes? Do you have a value for result if you try to print it?

[hamidrabedi]

@Gagaro I found where the problem is, when i try to delete one object normally everything works just fine, but when i call the queryset.delete method in the admin, it raises the error:

what gets called in django admin

So when you delete one object there is no response returning and it tries to unpack it :

[hamidrabedi]

Do you have more parent classes? Do you have a value for result if you try to print it?

there is no result it raises errors

[Gagaro]

What classes are you inheriting from?

[hamidrabedi]

@Gagaro
from safedelete.admin import SafeDeleteAdmin
from safedelete.models import SafeDeleteModel

[Gagaro]

It looks good to me. Could you maybe step into all the subsequent delete() to be sure there isn't one which does not return anything?

[hamidrabedi]

@Gagaro Oh i see, delete got overridden and is returning data.ok i got it.