因此，我一直在关注与依赖下拉列表相关的本教程，该下拉列表可以在here中找到，而且我似乎陷入了else if语句的最后一部分，并且无法在我的项目中实现 postlog models.py：

from django.db import models

# Create your models here.
class FlightNum(models.Model):
    fl_no =models.CharField(max_length=5,primary_key=True)

    def __str__(self):
        return self.fl_no

class Destination(models.Model):
    fl_no= models.OneToOneField(FlightNum,on_delete=models.CASCADE,related_name='fl1')
    dest= models.CharField(max_length=15,blank=True)

    def __str__(self):
        return self.dest

class Parking(models.Model):
    fl_no= models.OneToOneField(FlightNum,related_name='fl2')
    park_bay= models.CharField(max_length=3)

    def __str__(self):
        return self.park_bay

class DepartureTime(models.Model):
    fl_no= models.OneToOneField(FlightNum,related_name='fl3')
    dep_time= models.CharField(max_length=9)

    def __str__(self):
        return self.dep_time

class Flight(models.Model):
    fl_no= models.OneToOneField(FlightNum,primary_key=True,related_name='fl4')
    park_bay= models.ForeignKey(Parking,on_delete=models.CASCADE)
    dest= models.ForeignKey(Destination,on_delete=models.CASCADE)
    dep_time= models.ForeignKey(DepartureTime,on_delete=models.CASCADE)
    inbound= models.CharField(max_length=15,blank=True)
    airline= models.CharField(max_length=15)
    arr_time= models.TimeField()

状态模型。py：

from django.db import models
from postlog.models import FlightNum,Destination,Parking,DepartureTime

# Create your models here.
class FlightStatus(models.Model):
    CLEANING_CHOICES = (
        ('Yes','Yes'),('No','No'),)
    fl_no= models.OneToOneField(FlightNum,related_name='fli_no',primary_key=True)
    park_bay= models.ForeignKey(Parking,related_name='parki_bay')
    catering= models.CharField(max_length=9)
    fuel= models.IntegerField()
    pas_cnt= models.IntegerField()
    dest= models.ForeignKey(Destination,related_name='desti',null=True)
    dep_time=models.ForeignKey(DepartureTime,related_name='dept_time')
    Cleaning = models.CharField( max_length=3,choices=CLEANING_CHOICES)

状态表格。

from django.forms import ModelForm
from status.models import FlightStatus
from postlog.models import FlightNum,DepartureTime


class StatusForm(ModelForm):
    class Meta:
        model = FlightStatus
        fields = ('fl_no','park_bay','catering','fuel','pas_cnt','dest','dep_time','Cleaning')
        labels = {
            'fl_no': ('Flight Number'),'park_bay': ('Parking Bay'),'catering': ('Catering'),'fuel': ('Fuel'),'pas_cnt': ('Passenger Count'),'dest': ('Destination'),'dep_time': ('Departure Time'),'Cleaning': ('Cleaning'),}

    def __init__(self,*args,**kwargs):
        super().__init__(*args,**kwargs)
        self.fields['park_bay'].queryset = Parking.objects.none()
        self.fields['dest'].queryset = Destination.objects.none()
        self.fields['dep_time'].queryset = DepartureTime.objects.none()

        if 'fl_no' in self.data:
            try:
                flightid = int(self.data.get('fl_no'))
                self.fields['park_bay'].queryset = Parking.objects.filter(fl_no=flightid).order_by('park_bay')
                self.fields['dest'].queryset = Destination.objects.filter(fl_no=flightid).order_by('dest')
                self.fields['dep_time'].queryset = DepartureTime.objects.filter(fl_no=flightid).order_by('dep_time')
            except (ValueError,TypeError):
                pass
        elif self.instance.pk:
            self.fields['park_bay'].querysets = self.instance.fl_no.park_bay_set.order_by('park_bay')       
            self.fields['dest'].querysets = self.instance.fl_no.dest_set.order_by('dest')       
            self.fields['dep_time'].querysets = self.instance.fl_no.park_bay_set.order_by('dep_time')       

所以如果有人可以帮助我修复此部分：

elif self.instance.pk:
            self.fields['park_bay'].querysets = self.instance.fl_no.park_bay_set.order_by('park_bay')       
            self.fields['dest'].querysets = self.instance.fl_no.dest_set.order_by('dest')       
            self.fields['dep_time'].querysets = self.instance.fl_no.dep_time_set.order_by('dep_time')       

我真的很感激