django REST Framework - Integer field will not accept empty response?

Question

The models.py IntegerField is set-up:

class DMCAModel(models.Model):
    tick = models.CharField(max_length=20)
    percent_calc = models.FloatField()
    ratio = models.IntegerField(blank=True, null=True, default=None)   #The problem is here
    created_at = models.DateTimeField(auto_now_add=True)
    owner = models.ForeignKey(User, related_name='dmca',
                              on_delete=models.CASCADE, null=True)

serilaizers.py

class DMCASerializer(serializers.ModelSerializer):
    class Meta:
        model = DMCAModel
        fields = '__all__'
        # fields = ['id', 'tick', 'percent_calc', 'ratio']
# I have tried removing fields, if I remove 'ratio' then even if I send an input it is ignored.

api.py

class DmcaViewSet(viewsets.ModelViewSet):
    # queryset = DMCAModel.objects.all()
    permission_classes = [
        permissions.IsAuthenticated
    ]

    serializer_class = DMCASerializer

    def get_queryset(self):
        return self.request.user.dmca.all()

    def perform_create(self, serializer):
        # print(self.request.user)
        serializer.save(owner=self.request.user)

When I to make the following POST request from postman:

Authorization: Token xxxxxx
Body JSON:
{
"tick":"XYZ",
"percent_calc":"3",
"ratio":""
}

I get the error:

{ "ratio": [ "A valid integer is required." ] }

I think I have set the properties of the Models field correctly if I understand them correctly: null=True database will set empty to NULL, blank=True form input will be accepted, default=None incase nothing is entered. I have tried to use the properties one by one and see what happens. But can't work out the error.

Milos Bogdanovic · Accepted Answer · 2022-10-03T18:52:18.323

1

Inside your serializer, you can use a CharField for the ratio field if you want to send an empty string and then convert to Int in the validation method.

class DMCASerializer(serializers.ModelSerializer):
     ratio = serializers.CharField(required=False, allow_null=True, allow_blank=True)

     class Meta:
         model = DMCAModel
         fields = '__all__'

     def validate_ratio(self, value):
         if not value:
             return None
         try:
             return int(value)
         except ValueError:
            raise serializers.ValidationError('Valid integer is required')

Also, you need to change serializer_class inside DmcaViewSet from:

serializer_class = DcaSerializer

to

serializer_class = DMCASerializer

When I send an empty string:

When I send an Integer:

edited Oct 03 '22 at 18:52

answered Oct 03 '22 at 18:31

Milos Bogdanovic

221
1
6

Hi Milos, it still gives the same error. I have set the class Meta same as per my code as it wasn't included in yours. – Sid Oct 03 '22 at 18:38
1

Hi Sid, I updated the serializers.py. It should work. – Milos Bogdanovic Oct 03 '22 at 18:53
1

Thanks Milos. It works. Will start reading up more about this. – Sid Oct 03 '22 at 19:18

score 0 · Answer 2 · answered Oct 03 '22 at 17:12

0

Remove default = True. If blank = True then default = False, according to the docs.

But also, null = True means that the value will be required in forms. So removing null = True is also part of the solution.

Try this:

class DMCAModel(models.Model):
    tick = models.CharField(max_length=20)
    percent_calc = models.FloatField()
    ratio = models.IntegerField(blank=True)
    created_at = models.DateTimeField(auto_now_add=True)
    owner = models.ForeignKey(User, related_name='dmca', on_delete=models.CASCADE, null=True)

Heres a useful answer on the difference between null and blank, too. Its worth the read.

answered Oct 03 '22 at 17:12

Jordan

540
4
10

Still the same error. I removed `null=True` and `default=None`. Did `makemigrations` and `migrate`. – Sid Oct 03 '22 at 17:30
I read through the answer you mentioned. `blank=True, null=True` should be the solution. But it just doesn't seem to work on my end. – Sid Oct 03 '22 at 17:35
It seems to be an error in the `serializer`. – Sid Oct 03 '22 at 17:54

score 0 · Answer 3 · answered Oct 03 '22 at 18:57

Can you try passing this request

Authorization: Token xxxxxx
Body JSON:
{
"tick":"XYZ",
"percent_calc":"3",
"ratio": null
}

If you ware passing empty string then at the end it is string so it will raise ValidationError, also you are using modelserializer so by default it will validate against the type of model field. blank=True will not mean anything with integer.

django REST Framework - Integer field will not accept empty response?

3 Answers3