Broken __in lookup for keys of json field

[Maksim Iakovlev]

For example I have a model with json field:

class MyModel():
    model_field = JsonField()

I create 3 records in db:

x1 = MyModel(model_field={json_field=''}).save()
x2 = MyModel(model_field={json_field=None}).save()
x3 = MyModel(model_field={json_field='foobar'}).save()

And then I want for filter all records which contains non-empty json_field like this:

MyModel.objects.exclude(model_field__json_field__in=['', None])

I expect only x3 record in result, but x2 presents too. This is also wrong:

MyModel.objects.exclude(model_field__json_field='').exclude(model_field__json_field__isnull=True)

Only this filter works as expected:

MyModel.objects.exclude(model_field__json_field='').exclude(model_field__json_field=None)

[Mariusz Felisiak]

Replying to Maksim Iakovlev:

MyModel.objects.exclude(model_field__json_field__in=['', None])

I expect only x3 record in result, but x2 presents too.

This is a duplicate of #20024.

This is also wrong:

MyModel.objects.exclude(model_field__json_field='').exclude(model_field__json_field__isnull=True)

It's ​documented that __isnull on key transforms are using "To query for missing keys", not to query for a None value.