Spring Boot controller - Upload Multipart and JSON to DTO

Question

I want to upload a file inside a form to a Spring Boot API endpoint.

The UI is written in React:

export function createExpense(formData) {
  return         


        

Answer 1

Add the consumer type to your request mapping .it should work fine.

@POST
@RequestMapping("/upload")
public ResponseEntity<Object> upload(@RequestParam("file") MultipartFile file,consumes = "multipart/form-data") 
{
    if (file.isEmpty()) {
        return new ResponseEntity<Object>(HttpStatus.BAD_REQUEST);
    } else {
        //...
    }
}

Answer 2

You have to tell spring you're consuming multipart/form-data by adding consumes = "multipart/form-data" to the RequestMapping annotation. Also remove the RequestBody annotation from the expenseDto parameter.

@RequestMapping(path = "/{groupId}", consumes = "multipart/form-data", method = RequestMethod.POST)
public ExpenseSnippetGetDto create(ExpensePostDto expenseDto, 
   @PathVariable long groupId, Principal principal, BindingResult result) 
   throws IOException {
   //..
}

With the posted ExpensePostDto the title in the request is ignored.

Edit

You'll also need to change the content type to multipart/form-data. Sounds like that's the default for post based on some other answers. Just to be safe, I would specify it:

'Content-Type': 'multipart/form-data'