add QuerySet case in ListSerializer.to_representation method

[lsaavedr]

Description

QuerySet data type is added in to_representation method because in that case if QuerySet.all() is not called the result iterable is not updated and iterate over an "obsolete list".

Thanks!

[tomchristie]

Can you show us a simple example that needs this change?

[lsaavedr]

all "list" in autogenerate CRUD need this change if in your setting dont have a pagination class setted, comment pagination class and list objects, then remove one and list object again

REST_FRAMEWORK = {
    # "DEFAULT_PAGINATION_CLASS": "some..."
 }

[tomchristie]

Okay. Surprised we've not hit this issue before. Thanks for resolving this.

[tomchristie]

Looks like this introduces a failing test case...

=================================== FAILURES ===================================
[404](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:405)
_____________________ Issue2704TestCase.test_queryset_all ______________________
[405](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:406)
rest_framework/fields.py:447: in get_attribute
[406](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:407)
    return get_attribute(instance, self.source_attrs)
[407](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:408)
rest_framework/fields.py:97: in get_attribute
[408](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:409)
    instance = getattr(instance, attr)
[409](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:410)
E   AttributeError: 'OneFieldModel' object has no attribute 'additional_attr'
[410](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:411)

[411](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:412)
During handling of the above exception, another exception occurred:
[412](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:413)
tests/test_model_serializer.py:1025: in test_queryset_all
[413](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:414)
    assert serializer.data == expected
[414](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:415)
rest_framework/serializers.py:768: in data
[415](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:416)
    ret = super().data
[416](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:417)
rest_framework/serializers.py:253: in data
[417](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:418)
    self._data = self.to_representation(self.instance)
[418](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:419)
rest_framework/serializers.py:687: in to_representation
[419](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:420)
    self.child.to_representation(item) for item in iterable
[420](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:421)
rest_framework/serializers.py:687: in <listcomp>
[421](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:422)
    self.child.to_representation(item) for item in iterable
[422](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:423)
rest_framework/serializers.py:509: in to_representation
[423](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:424)
    attribute = field.get_attribute(instance)
[424](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:425)
rest_framework/fields.py:480: in get_attribute
[425](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:426)
    raise type(exc)(msg)
[426](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:427)
E   AttributeError: Got AttributeError when attempting to get a value for field `additional_attr` on serializer `TestSerializer`.
[427](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:428)
E   The serializer field might be named incorrectly and not match any attribute or key on the `OneFieldModel` instance.
[428](https://github.com/encode/django-rest-framework/runs/8158339360?check_suite_focus=true#step:6:429)
E   Original exception text was: 'OneFieldModel' object has no attribute 'additional_attr'.

Want to try taking a look into that? If you're not able to resolve what behaviour is being changed there then let me know.

[lsaavedr]

But

tests/test_model_serializer.py:47

class OneFieldModel(models.Model):
    char_field = models.CharField(max_length=100)

and the error seems to be that problem

E   AttributeError: Got AttributeError when attempting to get a value for field `additional_attr` on serializer `TestSerializer`.
E   The serializer field might be named incorrectly and not match any attribute or key on the `OneFieldModel` instance.
E   Original exception text was: 'OneFieldModel' object has no attribute 'additional_attr'.

is this needed?

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.