python - Django:TypeError - 'QuerySet' 类型的参数不可迭代

Question

所以这个错误很神秘，怎么可能是Queryset对象，即使是空的，也不是可迭代的吗？

这是我看到的罕见错误:

TypeError: argument of type 'QuerySet' is not iterable

这是产生此错误的代码:

artist_object = Artist.objects.get(id=id)
artist_release_groups = artist_object.release_groups.all()
if rg not in artist_release_groups: # this is the line where the error is  happening
    artist_object.release_groups.add(rg)

我不知道这是否相关，但这是在 celery 任务中发生的，并且在 Sentry(异常报告服务)中报告了错误。

我拥有的回溯:

TypeError: argument of type 'QuerySet' is not iterable
  File "celery/app/trace.py", line 382, in trace_task
    R = retval = fun(*args, **kwargs)
  File "celery/app/trace.py", line 641, in __protected_call__
    return self.run(*args, **kwargs)
  File "core/tasks.py", line 234, in refresh_artist_task
    get_apple_release_groups_for_artist(applemusic_id)
  File "celery/local.py", line 191, in __call__
    return self._get_current_object()(*a, **kw)
  File "celery/app/trace.py", line 642, in __protected_call__
    return orig(self, *args, **kwargs)
  File "celery/app/task.py", line 375, in __call__
    return self.run(*args, **kwargs)
  File "core/tasks.py", line 147, in get_apple_release_groups_for_artist
    if rg not in artist_release_groups:

更新:不确定，但我认为这与 this issue on the Django forums 有关. (见最后三个回复)

Answer 1

也许您应该在 if 中使用过滤器。
代替:
if rg not in artist_release_groups:
artist_object.release_groups.add(rg)
用

artist_release_groups_query = artist_object.release_groups.filter(id=rg.id)
if not artist_rease_groups_query.exists():
    # add the rest