File uploaded with Django Rest Framework shows null on database - api

Question

Created an API and while testing the JSON output I'm getting is
{
"id": 34,
"file_upload": null
}
While checking the admin panel, the new id is created but there is no uploaded image in that. And hence I'm not able to save it locally too.
Here's my urls.py
urlpatterns = [
path("api/", upload_file),
path("api-class/", UploadFileView.as_view())
]
I've created two paths one with function-based views and the other with class-based views, but neither is working.
views.py
class UploadFileView(APIView):
parser_classes = [MultiPartParser, FormParser,]
def get(self, request):
file = ApiSerializer.objects.all()
serializer = ApiSerializer(file, many=True)
return Response(serializer.data)
def post(self, request, format=None):
print(request.data)
serializer = ApiSerializer(data=request.data)
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)
#api_view(['POST'])
#parser_classes((MultiPartParser,))
def upload_file(request):
if request.method == 'POST':
serializer = ApiSerializer(data=request.data)
extension = 'csv'
ext = ['csv']
if extension in ext:
if serializer.is_valid():
serializer.save()
return Response(serializer.data, status=status.HTTP_201_CREATED)
else:
report = {'message':'Serializer wasn\'t valid. Error occured'}
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
else:
resp = {'message': "Invalid Format"}
return Response(resp, status=status.HTTP_400_BAD_REQUEST)
serializer.py
class ApiSerializer(serializers.ModelSerializer):
class Meta:
model = UserInput
fields = '__all__'
models.py
def file(instance, filename):
filename = filename.replace(" ", "")
return '\{0}'.format(filename)
def validate_file_extension(value):
import os
ext = os.path.splitext(value.name)[1]
valid_extensions = ['.csv']
if not ext in valid_extensions:
raise ValidationError(u'File not supported!')
class UserInput(models.Model):
file_upload = models.FileField(null=True, blank=True, upload_to='file', validators=[validate_file_extension])