Getting a serializer KeyError on a non-required field

Question

I am hitting a KeyError for 'children' when I run this create() function:

class TaskViewSet(ModelViewSet):
    queryset = Task.objects.all()
    serializer_class = TaskSerializer

    def create(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)            
        ...
        if serializer.is_valid(raise_exception=True):
            inputs = serializer.data // KeyError triggers on this line

This is where it is defined in the models:

class Task(models.Model):
    ...
    parent = models.ForeignKey('self', on_delete=models.CASCADE, null=True, blank=True, related_name='children')

And in my serializer:

class TaskSerializer(serializers.ModelSerializer):
    ...
    children = serializers.PrimaryKeyRelatedField(read_only=True, many=True, required=False, default=[])

    class Meta:
        model = Task
        fields = [
            ..., 'children',
        ]

The last few lines of the error:

File "/Users/adamstarrh/opt/anaconda3/envs/onit/lib/python3.9/site-packages/rest_framework/fields.py", line 95, in get_attribute
    instance = instance[attr]
KeyError: 'children'

I've set required to false and read_only to true in the serializer, and null to true in the models. What have I missed?

Answer 1

I bypassed this issue by using the serializer's validated_data instead:

def create(self, request, *args, **kwargs):
    ...
    if serializer.is_valid(raise_exception=True):
        inputs = serializer.validated_data