android - Retrofit and Multipart Image Uploading with HTTP 400 -

im start crying, because ive tried many solutions , topics, doesn`t work.

the issue: have upload string (it bitmap, have base64 coded) our lovely server, have created background thread in android it, , calling backend. http 400 error message, following message:

org.springframework.web.bind.missingservletrequestparameterexception","message":"required multipartfile parameter 'file' not present","path":"/backend/newimage"}. 

my headers:

content-disposition: form-data; name="file" content-type: text/plain; charset=utf-8 content-length: 24069 content-transfer-encoding: binary /9j/4aaqskzjrgabaqaaaqabaad/2wbdaa0jcgsk.......etc.....binary 

i don`t see in headers following part:

enctype: "multipart/form-data”). , don`t understand why, retforit interce looks this:

@post("/newimage") @multipart string uploadimagetoidea(@query("id") string id, @part("file") string file ); 

i don`t understand error message, because have file param here.

i had tried following (didn`t work obviously:

• retrofit multipart upload image failed
• retrofit - @body parameters cannot used form or multi-part encoding (added @headers, in case had more header before request, didn`t changed anything.)

my code call backend (not final version, first let things make work :) ):

   new thread() {                 @override                 public void run() {                     multiparttypedoutput file = new multiparttypedoutput();                     (int = 0; < imagestoupload.size(); ++i) {                         bitmap imagebitmap = imagestoupload.get(i);                         bytearrayoutputstream stream = new bytearrayoutputstream();                          imagebitmap.compress(bitmap.compressformat.jpeg, 60, stream);                         byte[] bytearray = stream.tobytearray();                         string bitmapstring = base64.encodetostring(bytearray, base64.default);                         backend.uploadimagetoidea(submitidearesponse.getideadetails().getid(), bitmapstring);                     }                 }             }.start(); 

note backend developer:

you need send multipart request (enctype="multipart/form-data”).

so, can please me out, why have http 400 error message above? can change in code make call work ? thank you

you should use typedfile sending file in multipart.

@multipart @post("/newimage") string uploadimagetoidea(@part("id") typedstring id, @part("file") typedfile file); 

for more information link.