RetrieveUpdateAPIView Field 'id' expected a number but got <User: Chris>

Question

I am trying to update a customer with Django Rest Framework but I get this error:

Field 'id' expected a number but got <User: Chris>.

'Chris' is the username of the user.

If I remove the 'pk' and 'accounts' for the serializer it will not be a problem, but I need those properties for an other function to work.

It says that the property full_name from customer expected an number but got user, which makes sense but how do I then convert it to the user 'id'?

return f'{self.user.first_name} {self.user.last_name}' 

Error in formatting: TypeError: Field 'id' expected a number but got <User: Chris>.

This is my class-based view using RetrieveUpdateAPIView

class staff_customer_details(generics.RetrieveUpdateAPIView):
    serializer_class = CustomerSerializer
    permissions_classes = [permissions.IsAuthenticated, ]
    queryset = Customer.objects.all()

and the model and serializer looks like this:

class Customer(models.Model):
    user        = models.OneToOneField(User, primary_key=True, on_delete=models.PROTECT)
    rank        = models.CharField(choices=RANK_CHOICES, max_length=7)
    personal_id = models.IntegerField(db_index=True)
    phone       = models.CharField(max_length=35, db_index=True)

    @property
    def full_name(self) -> str:
        return f'{self.user.first_name} {self.user.last_name}'



class CustomerSerializer (serializers.ModelSerializer):
    user = serializers.PrimaryKeyRelatedField(read_only=True)
    accounts = AccountSerializer(many=True, read_only=True)

    class Meta:
        fields = ('user', 'pk', 'rank', 'personal_id', 'phone', 'accounts',  'can_make_loan', 'full_name')
        model = Customer

Answer 1

I think the reason is that you set primary_key = True in user field of the Customer model.

Please remove that attribute. Then django will set the default primary_key field, that is id, in the Customer model.

And in CustomerSerializer, the pk should be changed into id.