DRF How to patch when file upload is required...?

Question

DRF How do you patch when file upload is required and you don't want to post the file again?

I keep getting this response: {'xyz_file': [u'No file was submitted.']}

I don't have xyz_file required on the serializer. This is not a field on the model because I don't want to save it in the db.

class XYZSerializer(ParentSerializer):
    xyz_file = serializers.FileField(source='get_file_field', use_url=False, validators=[xyz_extensions_validator])

    class Meta:
        model = models.XYZModel
        fields = ('name', 'xyz_file', 'active',)

I've tried overwriting the update method in the view and serializer. Neither worked.

Answer 1

Ok so this is how i fixed my problem.

In my serializer I added this method:

def exclude_fields(self, fields_to_exclude=None):
    if isinstance(fields_to_exclude, list):
        for f in fields_to_exclude:
            f in self.fields.fields and self.fields.fields.pop(f) or next()

In my viewset I overrode the update method with this:

def update(self, request, *args, **kwargs):
    partial = False
    if 'PATCH' in request.method:
        partial = True
    instance = self.get_object()
    serializer = self.get_serializer(instance, data=request.data, partial=partial)
    if 'xyz_file' in request.data and not request.data['xyz_file']:
        serializer.exclude_fields(['xyz_file'])
    if not serializer.is_valid():
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
    serializer.save()
    return Response(serializer.data)

So the idea is to remove the field from even being validated. Also if you wanted to run this on a field that is on the model, the popping of the field will prevent you from saving the non validated field.

Answer 2

If you are using PATCH HTTP method, then you could turn on partial updates, which doesnt require any fields I believe.

Then you define your serializer inside your update method in your view:

serializer = XYZSerializer(instance=xyz,data=request.data,partial=True)

Is written here http://www.django-rest-framework.org/api-guide/serializers/#partial-updates.