drf_server.py

from rest_framework.parsers import FileUploadParser, MultiPartParser
from rest_framework.views import APIView
from rest_framework.response import Response

class FileUploadView(APIView):
    parser_classes = (FileUploadParser, MultiPartParser)

    def put(self, request, filename, format=None):
        with open("uploaded_file", "wb") as f:
            f.write(request.data['file'].read())
        return Response(status=204)

---     
      
from rest_api.views import FileUploadView

urlpatterns = [
      url(r"^upload/(?P<filename>[^/]+)$", FileUploadView.as_view()),
]

file_upload.dart

import 'package:http/http.dart' as http;
import 'package:image_picker/image_picker.dart';

main() async {
  var image = await ImagePicker.pickImage(source: ImageSource.camera);
  final res = await http.put(
    "http://127.0.0.1:8000/api/upload/test",
    body: await image.readAsBytes(),
  );
  print(res.statusCode);
  print(res.body);
}