每当 Django 中有可供选择的选项时，如何要求依赖下拉菜单？答案

【问题标题】：How to require dependent drop down whenever there are options to choose from in Django?每当 Django 中有可供选择的选项时，如何要求依赖下拉菜单？
【发布时间】：2020-03-29 13:09:56
【问题描述】：

我有一个带有相关下拉列表的表单。目前，我已将其设置为只有在其中有可用选项时才会显示第二个下拉菜单，否则会隐藏。我遇到的问题是，每当您选择具有辅助（站）下拉列表的主要（工作区）选项时，您可以提交表单而无需从依赖（辅助）下拉列表中选择选项，只要有选项，就应该需要它。

我如何修改它，以便在出现时需要依赖下拉菜单？

models.py

class WorkArea(models.Model):
    name = models.CharField(max_length=50)

    def __str__(self):
        return self.name


class Station(models.Model):
    work_area = models.ForeignKey(WorkArea, on_delete=models.CASCADE, related_name="stations")
    name = models.CharField(max_length=50)

    def __str__(self):
        return self.name


class EmployeeWorkAreaLog(TimeStampedModel, SoftDeleteModel, models.Model):
    employee_number = models.ForeignKey(Salesman, on_delete=models.SET_NULL, help_text="Employee #", null=True, blank=False)
    work_area = models.ForeignKey(WorkArea, on_delete=models.SET_NULL, null=True, blank=False, help_text="Work Area", related_name="work_area")
    station_number = models.ForeignKey(Station, on_delete=models.SET_NULL, null=True, help_text="Station", related_name="stations", blank=True)

forms.py

class WarehouseForm(AppsModelForm):
    class Meta:
        model = EmployeeWorkAreaLog
        widgets = {
            'employee_number': ForeignKeyRawIdWidget(EmployeeWorkAreaLog._meta.get_field('employee_number').remote_field, site, attrs={'id':'employee_number_field'}),
        }
        fields = ('employee_number', 'work_area', 'station_number')


    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.fields['station_number'].queryset = Station.objects.none()

        if 'work_area' in self.data:
            try:
                work_area_id = int(self.data.get('work_area'))
                self.fields['station_number'].queryset = Station.objects.filter(work_area_id=work_area_id).order_by('name')
            except (ValueError, TypeError):
                pass
        elif self.instance.pk:
            self.fields['station_number'].queryset = self.instance.work_area.stations.order_by('name')

views.py

def enter_exit_area(request):
    enter_without_exit = None
    exit_without_enter = None

    if request.method == 'POST':
        # Form handling...

def load_stations(request):
    work_area_id = request.GET.get('work_area')
    stations = Station.objects.filter(work_area_id=work_area_id).order_by('name')
    return render(request, 'operations/station_number_dropdown_options.html', {'stations': stations})

urls.py

urlpatterns = [
    url(r'enter-exit-area/$', views.enter_exit_area, name='enter_exit_area'),

    path('ajax/load-stations/', views.load_stations, name='ajax_load_stations'),
]

station_number_dropdown_options.html

<option value="">---------</option>
{% for station in stations %}
<option value="{{ station.pk }}">{{ station.name }}</option>
{% endfor %}

我尝试将其添加到 forms.py（Box Assembly 是具有站点的选项之一）

    def clean(self):
        cleaned_data = super().clean()
        work_area = cleaned_data['work_area']
        station = cleaned_data['station_number']
        if work_area in ('Box Assembly', 'Other) and station is None:
            raise forms.ValidationError("You must select a station")

但是，在调试器上运行时，我看到了这一点，但表单并没有引发任何错误。有什么我没听懂的吗？

【问题讨论】：

标签： python django

【解决方案1】：

WorkArea 不是字符串。您应该与属性name 进行比较。

def clean(self):
    cleaned_data = super().clean()
    work_area = cleaned_data['work_area']
    station = cleaned_data['station_number']

    if work_area.name == 'Box Assembly' and station is None:
            raise forms.ValidationError("You must select a station")

【讨论】：