如何从 Django 中的发布请求中设置外键

Question

I have this models

class Driver(models.Model):
    first_name = models.CharField(max_length=250)
    last_name = models.CharField(max_length=250)
    created_at = models.DateTimeField(default=NOW)
    updated_at = models.DateTimeField(default=NOW)
    def __str__(self):
        return self.first_name      


class Vehicle(models.Model):
    driver_id = models.ForeignKey(Driver,on_delete=SET_NULL,unique=True,null=True, blank=True)
    make = models.CharField(max_length=150)
    model = models.CharField(max_length=150)
    plate_number = models.CharField(max_length=10,validators = [validate_plate_numberLATIN,validate_plate_numberCYRYLLIC], unique=True)
    created_at = models.DateTimeField(default=NOW)
    updated_at = models.DateTimeField(default=NOW)
    def __str__(self):
        return self.make

I try to set foreign key in my post request into Vehicle model

    @method_decorator(csrf_exempt, name='dispatch')
    def post(self,request,*args, **kwargs):
        body = json.loads(request.body.decode("utf-8"))
        newCar = Vehicle.objects.create(driver_id=body['driver_id'],make=body['make'],model=body['model'],plate_number=body['plate_number'])
        data = json.loads(serializers.serialize('json',[newCar]))
        return JsonResponse({'success':data})

And get this error ValueError: Cannot assign "1": "Vehicle.driver_id" must be a "Driver" instance. How to get rid off this error? How I can create an instance of Driver and 'post' an id?

Answer 1

The raw value of a ForeignKey can be accessed by appending "_id" to the field name, this can also be used to create an instance using the raw value

Vehicle.objects.create(driver_id_id=body['driver_id'], ...)

Answer 2

You can do it in 2 ways

1. If you need the driver instance in somewhere in the code you can use this driver_instance = Driver.objects.get(pk=body['driver_id']) Vehicle.objects.create(driver_id=driver_instance,..)

Vehicle.objects.create(driver_id_id=body['driver_id'], ...)