How to send a blank file in multipart request

Question

I am unable to send a blank file using http request in flutter. The server is giving me exception '500'. Also I need to send a parameter "Filename" cuz it's not optional, otherwise I can just skip it if file is null.

here's the code:

  final Uri _saveTaskUrl =
      Uri.parse('http://————————);

  Future addNewTask(
      {File image,
      taskName,}) async {
// Intilize the multipart request
final imageUploadRequest = http.MultipartRequest('POST', _saveTaskUrl);

// Attach the file in the request

  final mimeTypeData =
      lookupMimeType(image?.path ?? '', headerBytes: [0xFF, 0xD8])
          .split('/');

   //Error is here
//////////////////////////////////////////////////////////
   //what to do here if i want to send a blank image file
  final file = await http.MultipartFile.fromPath('FileName', image?.path ?? ''
      ,contentType: MediaType(mimeTypeData[0], mimeTypeData[1]));
////////////////////////////////////////////////////////
  imageUploadRequest.files.add( file);


imageUploadRequest.headers.addAll({
  "token": centralstate.loginData["AuthToken"],
  "clientid": centralstate.loginData["ClientId"].toString(),

});


    imageUploadRequest.fields['taskName'] = taskName;


    try {

      final streamedResponse = await imageUploadRequest.send();
      final response = await http.Response.fromStream(streamedResponse);
      if (response.statusCode != 200) {

        print(
            'Error while adding new task : ${response.statusCode} : ${response.body}');
        return 0;
      }


      print(responseData);

      return 1;
    } catch (e) {

      return 0;
    }
  }

from the blank file I mean something like this: Screenshot from the postman

I know I can use if statement to check file!=null, but I explicitly want to send a blank file.

Answer 1

http.MultipartRequest request = http.MultipartRequest(
    "POST",
    Uri.parse(baseUrl + "api/profiles/v1/update/"),
  )
    ..fields['first_name'] = firstName
    ..fields['last_name'] = lastName
    ..fields['phone'] = phone
    ..fields['full_name'] = fullName
    ..fields['country'] = 'Uzbekistan'
    ..fields['city'] = 'Tashkent'
    ..fields['date_birth'] = dateBirth!;

  if (req.image == null) {
    request.fields['image'] = '';
  } else {
    var picture = await http.MultipartFile.fromPath(
      'image',
      req.image!,
      filename: req.image!.split('/').last,
    );
    request.files.add(picture);
  }
  var response = await request.send();
  var responsed = await http.Response.fromStream(response);
  print(responsed.body);