django/rest: Can I have serializer with only one field?

Question

I'm using django 1.11.5 and python 3.5.

Using rest-framework, I want to search a patient having uid.

When I'm trying to have a serializer with only one field I get the error Thefieldsoption must be a list or tuple or "__all__". Got str..

Is there any solution to have only one field to search a user?

serializers.py

class GetUserSerializer(serializers.ModelSerializer):
    id = serializers.CharField(source='uid')

    class Meta:
        model = User
        fields = ('id')

views.py

class GetUser(CreateAPIView):
    permission_classes = ()
    serializer_class = GetUserSerializer

    def get(self, request):
        serializer = GetUserSerializer(data=request.data)
        # Check format and unique constraint
        if not serializer.is_valid():
            return Response(serializer.errors, \
                            status=status.HTTP_400_BAD_REQUEST)
        data = serializer.data


        if User.objects.filter(uid = data['id']).exists():
            user = User.objects.get(uid = data['id'])
            resp = {"user":{"uid":user.uid, "firstname":user.firstname, "yearofbirth": user.yearofbirth, \
                            "lastnames": user.lastname, "othernames": user.othernames}}
            return Response(resp, status=status.HTTP_200_OK)

        else:

            resp = {"error": "User not found"}
            return Response(resp, status=status.HTTP_404_NOT_FOUND)

models.py

class User(models.Model):
    uid = models.CharField(max_length=255, unique=True,default="0")
    firstname = models.CharField(max_length=255)
    lastname = models.CharField(max_length=255, blank=True)
    othernames = models.CharField(max_length=255, blank=True)
    yearofbirth = models.SmallIntegerField(validators=[MinValueValidator(1900),
                                           MaxValueValidator(2018)], null = False

Answer 1

You need to specify a tuple in the fields option:

fields = ('id', )

If you don't add the comma , python sees ('id') as a string. That's why you see the Got str. in the error message.

You can test it:

>>> type(('id'))
<type 'str'>

vs

>>> type(('id',))
<type 'tuple'>

Answer 2

You need to specify a tuple with one element, which requires a comma: ('uid',).