Problems POSTing an object with a serialiser with nested objects

[misty orchid]

I've got a problem trying to POST data to an object ilke this:

Models

A place that is in a city.

class City(models.Model):
  name = models.Charfield(max_length=50)

class Place(models.Model):
  name = models.Charfield(max_length=50)
  city = models.ForeignKey(City)

Serializers

I use a nested serializer to get the city within a place, so that i dont have to make 2 api calls whenever i want to display "{place,name} in {city.name}"

class CitySerializer(ModelSerializer):
  class Meta:
    model = City
    fields = '__all__'

class PlaceSerializer(ModelSerializer):
  city = CitySerializer(read_only=True)
  class Meta:
    model = Place
    fields = '__all__'

Views

I just use modelviewsets

class CityViewSet(ReadOnlyModelViewSet):
    queryset = models.City.objects.all()
    serializer_class = serial.CitySerializer

class PlaceViewSet(ReadOnlyModelViewSet):
    queryset = models.Place.objects.all()
    serializer_class = serial.PlaceSerializer

However, I only care about this extra info when I list or retrieve from the API. I'm not interested in creating a place and a scity at the same time.

However, when i try to POST a Place (using the API GUI), it always throws an error that city_id is missing.

This is the POST request contents:

{
"name": "new place",
"city": 1
}

IntegrityError at /API/place/

NOT NULL constraint failed: form_place.city_id

Seeing this error i tried using city_id instead of city but that also didn't work.

{
"name": "new place",
"city_id": 1
}

What is happening, and how could I fix it so that I can both:

• Get the nested data from list or retrieve operations
• POST models to the API using the plain fields (without nested stuff)
  ?

I thought maybe I could change the viewset classes so that they use a nested serializer for list and retrieve, and a plan serializer for the other operations, but maybe there's a better solution.

[wide flower]

the read_only=True is likely a problem here, you can't have that for a serializer used to create an instance. at least not if the associated model field must have a value

btw I very much recommend you drop the __all__ and replace it with a list of fields each. this will come to bite you sooner than later, especially with nested serializers. it helps a lot regarding longterm maintenance to write these things out

[heavy elm]

As far as I understood root reason os that you have ForeignKey field which always forces you to pass value of instance of such FK model when you try to create child object

So it's not about optinal field issue, it's about models dependency