How to pass multipart request parameter in rest template spring boot? - spring-boot

Question

I have following controller code in one microservice :
#PostMapping("/posts/{postId}/images")
#RolesAllowed({Roles.USER, Roles.ADMIN})
public ResponseEntity<UploadImageResponse> uploadFile(#RequestParam("image") MultipartFile file, #AuthenticationPrincipal String username, #PathVariable(name = "postId") String postId) {
ImageMetadataEntity metadata = imageService.upload(file, username, postId);
UploadImageResponse uploadImageResponse = new UploadImageResponse(metadata.getFilename(), metadata.getUri(), metadata.getFileType(), metadata.getPostId());
return new ResponseEntity<>(uploadImageResponse, HttpStatus.CREATED);
}
I am calling this API from other microservice using rest template like below:
#Override
public UploadImageResponse uploadFile(UploadImageRequest request) {
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.MULTIPART_FORM_DATA);
headers.add(HttpHeaders.AUTHORIZATION, Constants.BEARER + " " + TokenContext.get());
MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
body.add("image", request.getFile().getBytes());
HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<>(body, headers);
ResponseEntity<UploadImageResponse> response = restTemplate
.postForEntity(String.format(IMAGE_UPLOAD_URL, MEDIA_SERVICE_HOST, request.getPostId()), requestEntity, UploadImageResponse.class);
return response.getBody();
}
But somehow this is not working. I am getting the below error :
2022-11-27 18:52:56.829 WARN 11120 --- [nio-8000-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.web.multipart.support.MissingServletRequestPartException: Required request part 'image' is not present]
But in when debugged HttpServletRequest.multipartParameterNames has the 'image' field i am sending.
Can someone tell me what is wrong ?

Answer 1

The issue is that the file is sent in request as request.getFile().getBytes(). When request comes to controller, spring checks for the file name and if its present then its added in multiPartFiles else they will be added in multiPartParameterNames in HttpServletRequest. When sent as getBytes(), the file name is null. I have fixed it by adding the below class
public class MultipartInputStreamFileResource extends InputStreamResource {
private final String filename;
public MultipartInputStreamFileResource(InputStream inputStream, String filename) {
super(inputStream);
this.filename = filename;
}
#Override
public String getFilename() {
return this.filename;
}
#Override
public long contentLength() throws IOException {
return -1;
}
}
and the request now is changed as this :
MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
body.add("image", new MultipartInputStreamFileResource(request.getFile().getInputStream(), request.getFile().getOriginalFilename()));