That's not how you send file on postman. What you did is sending a string which is the path of your image, nothing more.
What you should do is;
You're ready to go.
In your Django view,
from rest_framework.views import APIView
from rest_framework.parsers import MultiPartParser
from rest_framework.decorators import parser_classes
@parser_classes((MultiPartParser, ))
class UploadFileAndJson(APIView):
def post(self, request, format=None):
thumbnail = request.FILES["file"]
info = json.loads(request.data['info'])
...
return HttpResponse()