Django填充选择字段

Question

I am working with four tables:

class Product(models.Model):
    active = models.BooleanField(default=True)
    name = models.CharField(max_length=40, unique=True)
    acronym = models.CharField(max_length=3, unique=True)

class Alarm(models.Model):
    active = models.BooleanField(default=True)
    product = models.ForeignKey(Product) #NEW
    name = models.CharField(unique=True, max_length=35)
    image_file = models.CharField(max_length=30)

class File(models.Model):
    reference = models.CharField(max_length=40)
    product = models.ForeignKey(Product, related_name='item_product') #NEW
    created = models.DateTimeField(default=datetime.now)
    created_by = models.ForeignKey(User)

class FileAlarm(models.Model):
    file = models.ForeignKey(File)
    created = models.DateTimeField()
    created_by = models.ForeignKey(User, related_name="alarm_created_by")
    alarm_date = models.DateField(default=datetime.now)
    alarm_type = models.ForeignKey(Alarm)
    alarm_comment = models.CharField(max_length=80, blank=True, null=True)

Unfortunatly I need to pass an onChange event to the form element of FileAlarm.alarm_type (which means the queryset in __init__ wont work) so I need to populate the choices= variable of ChoiceField . I'm just wondering how to do that since I only want alarms that are active and linked to the same product s as the File which the FileAlarm is linked.

class FileAlarmForm(ModelForm):

    def __init__(self,file,*args,**kwargs):
        super(FileAlarmForm, self).__init__(*args, **kwargs)
        self.fields['alarm'].queryset = Alarm.objects.filter(product__id=file.product_id)

    alarm_type = ChoiceField(required=True, widget=Select(attrs={'onChange':'updateAlarmImage'}))  # << ?!?

Answer 1

It turns out the best way round it was:

class FileAlarmForm(ModelForm):

    def __init__(self,file,*args,**kwargs):
        super(FileAlarmForm, self).__init__(*args, **kwargs)
        p = Product.objects.get(id=file.product_id)
        self.fields['alarm_type'].widget = Select(attrs={'onchange':'updateAlarmImage'})
        self.fields['alarm_type'].queryset = Alarm.objects.filter(product=p)