Фреймворк Django rest: ошибка при публикации () для внешнего ключа

Я пытаюсь сделать простой get() post() для моей базы данных. У меня есть существующая база данных, и я использовал inspectdb для создания из нее models.py. Я столкнулся с проблемой настройки составного первичного ключа для модели, и часть этих ключей является внешним ключом.

Модель TestCase имеет отношение внешнего ключа к модели TestSuite. API get() для TestCase работает хорошо. Однако сообщение завершается с ошибкой ниже:

File "/usr/local/lib/python3.6/dist-packages/django/core/handlers/exception.py" in inner
35.             response = get_response(request)

File "/usr/local/lib/python3.6/dist- packages/django/core/handlers/base.py" in _get_response
128.                 response = self.process_exception_by_middleware(e, request)

File "/usr/local/lib/python3.6/dist-packages/django/core/handlers/base.py" in _get_response
126.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/usr/local/lib/python3.6/dist-packages/django/views/decorators/csrf.py" in wrapped_view
54.         return view_func(*args, **kwargs)

File "/usr/local/lib/python3.6/dist-packages/rest_framework/viewsets.py" in view
116.             return self.dispatch(request, *args, **kwargs)

File "/usr/local/lib/python3.6/dist-packages/rest_framework/views.py" in dispatch
495.             response = self.handle_exception(exc)

File "/usr/local/lib/python3.6/dist-packages/rest_framework/views.py" in handle_exception
455.             self.raise_uncaught_exception(exc)

File "/usr/local/lib/python3.6/dist-packages/rest_framework/views.py" in dispatch
492.             response = handler(request, *args, **kwargs)

File "/usr/local/lib/python3.6/dist-packages/rest_framework/mixins.py" in create
20.         serializer.is_valid(raise_exception=True)

File "/usr/local/lib/python3.6/dist-packages/rest_framework/serializers.py" in is_valid
236.                 self._validated_data = self.run_validation(self.initial_data)

File "/usr/local/lib/python3.6/dist-packages/rest_framework/serializers.py" in run_validation
434.         value = self.to_internal_value(data)

File "/usr/local/lib/python3.6/dist-packages/rest_framework/serializers.py" in to_internal_value
491.                 validated_value = field.run_validation(primitive_value)

File "/usr/local/lib/python3.6/dist-packages/rest_framework/relations.py" in run_validation
160.         return super(RelatedField, self).run_validation(data)

File "/usr/local/lib/python3.6/dist-packages/rest_framework/fields.py" in run_validation
536.         value = self.to_internal_value(data)

File "/usr/local/lib/python3.6/dist-packages/rest_framework/relations.py" in to_internal_value
263.             return self.get_queryset().get(pk=data)

File "/usr/local/lib/python3.6/dist-packages/django/db/models/query.py" in get
407.             (self.model._meta.object_name, num)

Exception Type: MultipleObjectsReturned at /dqf_api/test_case/
Exception Value: get() returned more than one TestSuite -- it returned 
2!
Request information:
USER: AnonymousUser

Доступные для просмотра вызовы API также завершаются с ошибкой выше.

модели.py

class TestCase(models.Model):
    team_name = models.ForeignKey(TestSuite, on_delete=models.DO_NOTHING, db_column='team_name')
    suite_name = models.ForeignKey(TestSuite, on_delete=models.DO_NOTHING, db_column='suite_name')
    case_name = models.CharField(max_length=100, primary_key=True)
    test_type = models.ForeignKey(TestCaseType, on_delete=models.DO_NOTHING)

    class Meta:
        managed = False
        db_table = 'test_case'
        unique_together = (('team_name', 'suite_name', 'case_name'),)


class TestSuite(models.Model):
    team_name = models.ForeignKey(Team, on_delete=models.DO_NOTHING, db_column='team_name')
    suite_name = models.CharField(max_length=100, primary_key=True)
    description = models.CharField(max_length=200, blank=True, null=True)
    #Additional fields

    class Meta:
        managed = False
        db_table = 'test_suite'
        unique_together = (('team_name', 'suite_name'),)

class TestCaseType(models.Model):
    id = models.IntegerField(primary_key=True)
    name = models.CharField(max_length=100)
    description = models.CharField(max_length=200, blank=True, null=True)

    class Meta:
        managed = False
        db_table = 'test_case_type'

class Team(models.Model):
    team_name = models.CharField(primary_key=True, max_length=30)
    description = models.CharField(max_length=100, blank=True, null=True)

    class Meta:
        managed = False
        db_table = 'team'

просмотры.py

class TestCaseViewSet(viewsets.ModelViewSet):
   queryset = models.TestCase.objects.all()
   serializer_class = serializers.TestCaseSerializer

class TestSuiteViewSet(viewsets.ModelViewSet):
   queryset = models.TestSuite.objects.all()
   serializer_class = serializers.TestSuiteSerializer

сериализаторы.py

class TestSuiteSerializer(serializers.ModelSerializer):
    class Meta:
        model = models.TestSuite
        fields = '__all__'

class TestCaseSerializer(serializers.ModelSerializer):
    class Meta:
        model = models.TestCase
        fields = '__all__'

данные.json

{
"case_name": "NA",
"description": "NA",
"run_level": 1,
"stop_on_failure": false,
"team_name": "ede",
"suite_name": "dummy",
"test_type": 1
}

В таблице test_suite присутствует только одна запись с team_name =ede и suite_name = dummy.

Я новичок в Django и DRF. Любая помощь приветствуется.