Flutter image upload to SpringBoot server not working

Question

I'm trying to upload an image from my Flutter application using the following code:

Future<String> saveImage(File image) async {

  var stream = new http.ByteStream(DelegatingStream.typed(image.openRead()));
  var length = await image.length();
  String token = "blah"; //token for authentication

  var uri = Uri.parse(url);  //I get the URL from some config

  Map<String, String> headers = { "Authorization": "Bearer $token", "content-type": "multipart/form-data" };

  var request = new http.MultipartRequest("POST", uri);
  request.headers.addAll(headers);
  var multipartFile = new http.MultipartFile('file', stream, length);

  request.files.add(multipartFile);

  var response = await request.send();
  print(response.statusCode);
  response.stream.transform(utf8.decoder).listen((value) {
    print(value);
  });
}

But this request fails on my spring-boot server with the following error:

{"timestamp":1562637369179,"status":400,"error":"Bad Request","exception":"org.springframework.web.multipart.support.MissingServletRequestPartException","message":"Required request part 'file' is not present","path":"/api/v1/user/photo"}

This is what my Java controller method looks like:

@RequestMapping(value = "/photo", method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
public ResponseEntity<String> uploadImage(@RequestPart(required = true) @RequestParam("file") MultipartFile image) throws IOException {
        }

I would like to mention that the method works if I use postman to upload an image. There seems to be something wrong with my flutter code.

Thanks for any help.

Solution

Figured it out. Instead of using the new http.MultipartFile() constructor I used this static method:

request.files.add(await http.MultipartFile.fromPath('file', image.path,
    contentType: new MediaType('image', imageType)));

Comments

[Avi]

In @RequestPart default value for required is true so you don't have to mention that and remove @RequestParam instead do this `@RequestPart("file")