DRF easy method for reverse lookup to get a single item, not a list for 1:1 relations?-CodePudding

In my Django App I am using a model serializer for the API to get read access tot he objects in the DB. For one API call I have to provide data from different, but related objects in one result.

class Car(models.Model):
    name = models.Charfield()

class Driver(models.Model):
    name = models.Charfield()
    car = ForeignKey(Car, on_delete=models.CASCADE, null=Fals, blank=False)

The problem I have is that I always get back a list instead of a single object if I use nested serializers.

For example

class CarSerializer(serializers.ModelSerializer):
    driver = DriverSerilizer(source='driver_set', many=True, read_only=True)

gives back a list with one item if there is a driver. If I set "many=False" I get a list with one driver object where all values are null.

So I use a MethodSerializer now to get the first Item in the list, but that seems to be like a lame solution to me.

  driver = serializers.SerializerMethodField()

  def get_driver(self, obj):
      driver_list = DriverSerilizer(obj.driver_set.all(), many=True).data
      driver = None
      if len(driver_list) ==1:
          driver = driver_list[1]
      return driver

So it works, but isn't there a better way?

CodePudding user response：

That happens because you added a car as ForeignKey instead of OneToOneField, Django expected that you might add another or a lot of cars for one driver, However, if you make it OneToOneField then the driver mustn't have more than one car, Therefor at the OneToOneField case it should return a single field instead of a list and if you try to add many=True It would raise an error.