Field validation doesn'r work in serializer

Question

I've read a LOT of topics on validation yet I have no idea why this doesn't work. For example when width = 20 object still passes validation.

So I have this serializer:

class ImageUploadSerializer(serializers.ModelSerializer): 

    picture = Base64ImageField()

    class Meta:
        model = ImageUpload
        fields = ['id', 'url', 'picture']

    def validate_width(self, value):
        if value < 100:
            raise serializers.ValidationError('Width shouldn\'t be less then 100')
        return value

    def create(self, validated_data):
        im = Image.open(validated_data['picture'])
        width, height = im.size
        validated_data['name'] = f'{datetime.datetime.now()}'
        validated_data['width'] = width
        validated_data['height'] = height
        return super().create(validated_data)

And here's my view:

class ResizeImageView(APIView):
    serializer_class = ImageResizeSerializer

    def post(self, request, *args, **kwargs):
        width = request.data['width'] 
        height = request.data['height']
        with open('c:/Users/KK/Desktop/tiny-kitten-in-sunlight.jpg', 'rb') as img:
            mock_resized_obj = img.read()
            mock_resized_obj_64 = pybase64.b64encode_as_string(mock_resized_obj)

        serializer = ImageUploadSerializer(

                    data={'picture': mock_resized_obj_64,
                          'width': width, 
                          'height': height}
        )

        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

I know it is sloppy and all i just wanna know why validation doesn't work? I use one serializer to get parametres and another one to save and return data.

serializer I use to get parametres is:

class ImageResizeSerializer(serializers.Serializer):
    width = serializers.IntegerField()
    height = serializers.IntegerField()

Thank you beforehand!

Uzzal H. Mohammad · Accepted Answer · 2021-10-31 10:11:21Z

1

You can add the width field in the ImageUploadSerializer , you don't need another serializer to validate.

class ImageUploadSerializer(serializers.ModelSerializer): 

    picture = Base64ImageField()
    width = serializers.IntegerField()
    height = serializers.IntegerField()

    class Meta:
        model = ImageUpload
        fields = ['id', 'url', 'picture' , 'width' , 'height']

    def validate_width(self, value):
        if value < 100:
            raise serializers.ValidationError('Width shouldn\'t be less then 100')
        return value

    def create(self, validated_data):
        im = Image.open(validated_data['picture'])
        width, height = im.size
        validated_data['name'] = f'{datetime.datetime.now()}'
        validated_data['width'] = width
        validated_data['height'] = height
        return super().create(validated_data)

Its not validating because the ImageResizeSerializer missing the validation method, on the other hand ImageUploadSerializer was missing the field.

edited Oct 31, 2021 at 10:11

answered Oct 29, 2021 at 17:21

Uzzal H. Mohammad

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5 Comments

Vlad Vlad Over a year ago

Hello! Yes, that's what i thought as well, I've tried it but it doesn't work. It doesn't see this validation check. Mayby I should override some other methods in Serializer as well?

Uzzal H. Mohammad Over a year ago

Based on documentation this should have worked. Docs : django-rest-framework.org/api-guide/serializers , You can debug and check if the validation functions you wrote are actually being called on your expectations.

Vlad Vlad Over a year ago

yeah, I've tried to debug it with prints and it is not being called ever. I've read documentation a dozens times already, maybe I am missing something not sure. Anyways thank you for your help!

Uzzal H. Mohammad Over a year ago

I have updated the answer. Take a look if this one works.

Vlad Vlad Over a year ago

Yea, this works great! The problem is, I am not quite sure how to explain: I need ImageUploadSerializer to only show one field and it is the picture field and I use it for uploading the picture. I am using ImageResizeSerializer for another endpoint /images/<id>/resize format in which I resize the image.

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