Deserializing SlugRelatedField on ForeignKey with Django Rest Framework - django

Question

I am struggling to set a PrimaryKeyRelatedField using a SlugRelatedField.
My models.py looks like:
class Airport(models.Model):
name = models.CharField(max_length=200, blank=True)
iata = models.CharField(max_length=20, blank=True)
<other unrelated fields>
class Flight(models.Model):
flight_number = models.CharField(max_length=25, blank=False, unique=True)
origin = models.ForeignKey(Airport, related_name='origin', null=True)
destination = models.ForeignKey(Airport, related_name='destination', null=True)
scheduled_departure = models.DateTimeField(null=True)
scheduled_arrival = models.DateTimeField(null=True)
My view looks like:
class FlightList(APIView):
# List all flights, or create a new flight
queryset = Flight.objects.all()
serializer_class = FlightSerializer
def get(self, request, format=None):
flights = Flight.objects.all()
serializer = FlightSerializer(flights, many=True)
return Response(serializer.data)
def post(self, request, format=None):
serializer = FlightSerializer(data=request.data)
if serializer.is_valid():
serializer.save()
print serializer.validated_data
return Response(serializer.data, status=status.HTTP_201_CREATED)
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
If I set my serializers.py to:
class FlightSerializer(serializers.ModelSerializer):
class Meta:
model = Flight
fields = ('flight_number', 'origin', 'destination', 'scheduled_departure', 'scheduled_arrival')
From the shell I see the serializer renders to:
FlightSerializer():
flight_number = CharField(max_length=25, validators=[<UniqueValidator(queryset=Flight.objects.all())>])
origin = PrimaryKeyRelatedField(allow_null=True, queryset=Airport.objects.all(), required=False)
destination = PrimaryKeyRelatedField(allow_null=True, queryset=Airport.objects.all(), required=False)
scheduled_departure = DateTimeField(allow_null=True, required=False)
scheduled_arrival = DateTimeField(allow_null=True, required=False)
I am able to POST origin and destination pk's that match up with Airport entries in the database to create new flights. Great.
However, I actually need to post the airport code, (i.e.) LAX as the origin or destination, and have DRF figure out the appropriate instance.
I think the way to do this is using SlugRelatedField. Despite best efforts, I'm unable to set this up properly.
I am trying to set serializers.py like this:
class FlightSerializer(serializers.ModelSerializer):
origin = serializers.SlugRelatedField(
many=True,
read_only=True,
slug_field='iata',
)
class Meta:
model = Flight
fields = ('flight_number', 'origin', 'destination', 'scheduled_departure', 'scheduled_arrival')
When I pass up a valid airport code (iata) like KMS as the origin it seems to get ignored.
Is this what SlugRelatedField is supposed to be used for?
What am I doing wrong to allow my POST to send up a string, have DRF look at a field for matching db entries and store that as beautifully as it does when I simply pass up a valid PK?

Answer 1

Got some help from a colleague on this.
The problem was I was just misconfiguration of SlugRelatedField. To get at the airport codes, I needed to use a queryset and set the slug_field. That's all:
class FlightSerializer(serializers.ModelSerializer):
origin = serializers.SlugRelatedField(
slug_field='iata',
queryset=Airport.objects.all()
)
class Meta:
model = Flight
fields = ('flight_number', 'origin', 'destination', 'scheduled_departure', 'scheduled_arrival')