我有一个模型的表单，该表单跟踪输入/离开时间。我正在尝试添加约束以使数据更准确。

当前，当有人“输入”时，它会创建一条记录，将时间保存在时间戳中，然后进行重定向。如果此人随后尝试再次输入，则会创建带有新时间戳记的新记录。

我现在要添加的是，如果此人的上一个条目没有退出时间戳，那么该记录（将是最近的条目的倒数第二个）将通过更新来标记将time_exceptions 字段设置为“ N”。

当前，无论是否存在出口，它都会将所有字段都更改为“ N”，如下所示。

class EnterExitArea(CreateView):
    model = EmployeeWorkAreaLog
    template_name = "operations/enter_exit_area.html"
    form_class = WarehouseForm

    def form_valid(self,form):
        emp_num = form.cleaned_data['employee_number']
        area = form.cleaned_data['work_area']
        station = form.cleaned_data['station_number']

        if 'enter_area' in self.request.POST:
            form.save()
            EmployeeWorkAreaLog.objects.filter((Q(employee_number=emp_num) & Q(work_area=area) & Q(time_out__isnull=True) & Q(time_in__isnull=True)) & (Q(station_number=station) | Q(station_number__isnull=True))).update(time_in=datetime.now())

            if EmployeeWorkAreaLog.objects.filter(Q(employee_number=emp_num)).count() > 1:
                EmployeeWorkAreaLog.objects.filter((Q(employee_number=emp_num) & Q(work_area=area) & Q(time_out__isnull=True)) & (Q(station_number=station) | Q(station_number__isnull=True))).update(time_exceptions='N')

            return HttpResponseRedirect(self.request.path_info)

我尝试了以下操作，但是得到了expected string or bytes-like object，尽管它在崩溃前仍会创建一条新记录，但它不会将第二个的time_exceptions更新为N。

        if 'enter_area' in self.request.POST:
            form.save()
            EmployeeWorkAreaLog.objects.filter((Q(employee_number=emp_num) & Q(work_area=area) & Q(time_out__isnull=True) & Q(time_in__isnull=True)) & (Q(station_number=station) | Q(station_number__isnull=True))).update(time_in=datetime.now())

            if EmployeeWorkAreaLog.objects.filter(Q(employee_number=emp_num) & Q(time_out__isnull=True) & Q(time_exceptions="")).count() > 1:
                recent = EmployeeWorkAreaLog.objects.filter(employee_number=emp_num,work_area=area,station_number=station,time_out__isnull=True).order_by('-time_in')[1]

                EmployeeWorkAreaLog.objects.filter((Q(employee_number=emp_num) & Q(work_area=area) & Q(time_in=recent) & Q(time_out__isnull=True)) & (Q(station_number=station) | Q(station_number__isnull=True))).update(time_exceptions='N')

            return HttpResponseRedirect(self.request.path_info)

如何获取最近的第二个条目（如果有），以便将time_exceptions字段更新为“ N”？

跟踪：

Internal Server Error: /operations/enter-exit-area/
Traceback (most recent call last):
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\core\handlers\exception.py",line 34,in inner
    response = get_response(request)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\core\handlers\base.py",line 126,in _get_response
    response = self.process_exception_by_middleware(e,request)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\core\handlers\base.py",line 124,in _get_response
   response = wrapped_callback(request,*callback_args,**callback_kwargs)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\views\generic\base.py",line 68,in view
    return self.dispatch(request,*args,**kwargs)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\views\generic\base.py",line 88,in dispatch
    return handler(request,**kwargs)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\views\generic\edit.py",line 172,in post
    return super().post(request,line 142,in post
    return self.form_valid(form)
  File "C:\Users\mkusneco\apps.rsrgroup.com\apps\operations\views.py",line 45,in form_valid
    Q(station_number=station) | Q(station_number__isnull=True))).update(time_exceptions='N')
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\db\models\manager.py",line 82,in manager_method
    return getattr(self.get_queryset(),name)(*args,**kwargs)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\db\models\query.py",line 844,in filter
    return self._filter_or_exclude(False,line 862,in _filter_or_exclude
    clone.query.add_q(Q(*args,**kwargs))
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\db\models\sql\query.py",line 1263,in add_q
    clause,_ = self._add_q(q_object,self.used_aliases)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\db\models\sql\query.py",line 1281,in _add_q
    current_negated,allow_joins,split_subq)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\db\models\sql\query.py",line 1287,in _add_q
    split_subq=split_subq,File "C:\Users\mkusneco\appsve\lib\site-packages\django\db\models\sql\query.py",line 1225,in build_filter
    condition = self.build_lookup(lookups,col,value)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\db\models\sql\query.py",line 1096,in build_lookup
    lookup = lookup_class(lhs,rhs)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\db\models\lookups.py",line 20,in __init__
    self.rhs = self.get_prep_lookup()
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\db\models\lookups.py",line 70,in get_prep_lookup
    return self.lhs.output_field.get_prep_value(self.rhs)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\db\models\fields\__init__.py",line 1408,in get_prep_value
    value = super().get_prep_value(value)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\db\models\fields\__init__.py",line 1268,in get_prep_value
    return self.to_python(value)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\db\models\fields\__init__.py",line 1369,in to_python
    parsed = parse_datetime(value)
  File "C:\Users\mkusneco\appsve\lib\site-packages\django\utils\dateparse.py",line 106,in parse_datetime
    match = datetime_re.match(value)
TypeError: expected string or bytes-like object