Django视图集用Q对象查询报错：TypeError无法解包MatchAll对象

在Django视图集中使用Q对象进行多条件OR查询时触发TypeError: cannot unpack non-iterable MatchAll object，但相同逻辑在管理命令文件中运行正常；单条件普通filter查询可正常执行。

视图代码 #

@permission_classes((AllowAny,))
class ClipartViewSet(viewsets.GenericViewSet):
    serializer_class = ClipartSerializer
    queryset = Clipart.objects.filter(is_active=True).all()

    def list(self, request, **kwargs):
        # Some extra logic
        # qs = Clipart.objects.filter(name="Apes") # 此代码可正常运行
        qs = Clipart.objects.filter(Q(name="Apes") | Q(name="Dog"))  # 此代码触发错误

        print(qs)

        return super(ClipartViewSet, self).list(self, request, **kwargs)

错误信息 #

Internal Server Error: /api/s/configurator/cliparts
backend_1        | Traceback (most recent call last):
backend_1        |   File "/usr/local/lib/python3.7/site-packages/django/core/handlers/exception.py", line 47, in inner
backend_1        |     response = get_response(request)
backend_1        |   File "/usr/local/lib/python3.7/site-packages/django/core/handlers/base.py", line 181, in _get_response
backend_1        |     response = wrapped_callback(request, *callback_args, **callback_kwargs)
backend_1        |   File "/usr/local/lib/python3.7/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
backend_1        |     return view_func(*args, **kwargs)
backend_1        |   File "/usr/local/lib/python3.7/site-packages/rest_framework/viewsets.py", line 125, in view
backend_1        |     return self.dispatch(request, *args, **kwargs)
backend_1        |   File "/usr/local/lib/python3.7/site-packages/rest_framework/views.py", line 509, in dispatch
backend_1        |     response = self.handle_exception(exc)
backend_1        |   File "/usr/local/lib/python3.7/site-packages/rest_framework/views.py", line 469, in handle_exception
backend_1        |     self.raise_uncaught_exception(exc)
backend_1        |   File "/usr/local/lib/python3.7/site-packages/rest_framework/views.py", line 480, in raise_uncaught_exception
backend_1        |     raise exc
backend_1        |   File "/usr/local/lib/python3.7/site-packages/rest_framework/views.py", line 506, in dispatch
backend_1        |     response = handler(request, *args, **kwargs)
backend_1        |   File "/backend/mycomp/apps/ecommerce/configurator/views/design_views.py", line 109, in list
backend_1        |     qs = Clipart.objects.filter(Q(name="Apes") | Q(name="Dog"))  # This line will show error
backend_1        |   File "/usr/local/lib/python3.7/site-packages/django/db/models/manager.py", line 85, in manager_method
backend_1        |     return getattr(self.get_queryset(), name)(*args, **kwargs)
backend_1        |   File "/usr/local/lib/python3.7/site-packages/safedelete/queryset.py", line 72, in filter
backend_1        |     return super(SafeDeleteQueryset, queryset).filter(*args, **kwargs)
backend_1        |   File "/usr/local/lib/python3.7/site-packages/django/db/models/query.py", line 941, in filter
backend_1        |     return self._filter_or_exclude(False, args, kwargs)
backend_1        |   File "/usr/local/lib/python3.7/site-packages/django/db/models/query.py", line 961, in _filter_or_exclude
backend_1        |     clone._filter_or_exclude_inplace(negate, args, kwargs)
backend_1        |   File "/usr/local/lib/python3.7/site-packages/django/db/models/query.py", line 968, in _filter_or_exclude_inplace
backend_1        |     self._query.add_q(Q(*args, **kwargs))
backend_1        |   File "/usr/local/lib/python3.7/site-packages/django/db/models/sql/query.py", line 1391, in add_q
backend_1        |     clause, _ = self._add_q(q_object, self.used_aliases)
backend_1        |   File "/usr/local/lib/python3.7/site-packages/django/db/models/sql/query.py", line 1413, in _add_q
backend_1        |     split_subq=split_subq, check_filterable=check_filterable,
backend_1        |   File "/usr/local/lib/python3.7/site-packages/django/db/models/sql/query.py", line 1281, in build_filter
backend_1        |     arg, value = filter_expr
backend_1        | TypeError: cannot unpack non-iterable MatchAll object

解决方案 #

• 升级django-safedelete库：错误栈显示问题出在safedelete的QuerySet扩展中，旧版本的该库与Django的Q对象组合查询存在兼容性bug。升级到最新稳定版本即可解决。
• 修正视图逻辑：当前代码仅定义了qs但未替换视图的queryset属性，调用super().list()时仍会使用初始的queryset。正确写法：

  def list(self, request, **kwargs):
      self.queryset = Clipart.objects.filter(Q(name="Apes") | Q(name="Dog"))
      return super().list(request, **kwargs)
  

• 临时替代方案：如果暂时无法升级库，可用__in查询替代Q对象的OR逻辑，效果一致：

  self.queryset = Clipart.objects.filter(name__in=["Apes", "Dog"])
  

内容的提问来源于stack exchange，提问作者Arun SS