DoesNotExist: Problem installing fixture '<fixture.json>': <ClassModel> matching query does not exist.

[fpoulain]

Hi, I experienced an exception when loading a fixture of a projet using tracking fields. Not sure if it's a bug or feature (this long-living sqlite database might have minor inconsistencies).

Traceback (most recent call last):
  File "manage.py", line 27, in <module>
    execute_from_command_line(sys.argv)
  File "venv/lib/python3.7/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "venv/lib/python3.7/site-packages/django/core/management/__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "venv/lib/python3.7/site-packages/django/core/management/base.py", line 323, in run_from_argv
    self.execute(*args, **cmd_options)
  File "venv/lib/python3.7/site-packages/django/core/management/base.py", line 364, in execute
    output = self.handle(*args, **options)
  File "venv/lib/python3.7/site-packages/django/core/management/commands/loaddata.py", line 72, in handle
    self.loaddata(fixture_labels)
  File "venv/lib/python3.7/site-packages/django/core/management/commands/loaddata.py", line 114, in loaddata
    self.load_label(fixture_label)
  File "venv/lib/python3.7/site-packages/django/core/management/commands/loaddata.py", line 181, in load_label
    obj.save(using=self.using)
  File "venv/lib/python3.7/site-packages/django/core/serializers/base.py", line 226, in save
    getattr(self.object, accessor_name).set(object_list)
  File "venv/lib/python3.7/site-packages/django/db/models/fields/related_descriptors.py", line 997, in set
    self.add(*new_objs, through_defaults=through_defaults)
  File "venv/lib/python3.7/site-packages/django/db/models/fields/related_descriptors.py", line 938, in add
    through_defaults=through_defaults,
  File "venv/lib/python3.7/site-packages/django/db/models/fields/related_descriptors.py", line 1076, in _add_items
    model=self.model, pk_set=new_ids, using=db,
  File "venv/lib/python3.7/site-packages/django/dispatch/dispatcher.py", line 175, in send
    for receiver in self._live_receivers(sender)
  File "venv/lib/python3.7/site-packages/django/dispatch/dispatcher.py", line 175, in <listcomp>
    for receiver in self._live_receivers(sender)
  File "venv/lib/python3.7/site-packages/tracking_fields/tracking.py", line 405, in tracking_m2m
    objects = [model.objects.get(pk=pk) for pk in pk_set]
  File "venv/lib/python3.7/site-packages/tracking_fields/tracking.py", line 405, in <listcomp>
    objects = [model.objects.get(pk=pk) for pk in pk_set]
  File "venv/lib/python3.7/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "venv/lib/python3.7/site-packages/django/db/models/query.py", line 408, in get

Munging tracking.py the following way made it passing:

        # Get the model of the object being tracked
        tracked_model = instance._meta.model
        objects = []
        try:
            if pk_set is not None:
                objects = [model.objects.get(pk=pk) for pk in pk_set]
            _create_tracked_event_m2m(
                tracked_model, instance, sender, objects, action_event[action]
            )
        except:
            print(sender, instance, action, reverse, model, pk_set, using)

(actually tracking data is helpfull but in this case I don't care if they lack some buggy details)

[fpoulain]

Django Version: 2.2.8
Python Version: 3.7.3

[Gagaro]

At first glance, I'd say that you have a row which does not exists anymore in your database still referenced in a m2m.