Spring Boot, upload any amount of files in REST controller

Question

I'd like to create an endpoint which accepts any amount od different files from user.

For example:

Then, I'd like to receive it in my controller as a Map<String, FilePart> (or any other structure from which I'll know which file is which):

{
    "file1": "cactus-logo.png",
    "file2": "logo.png",
    "file3": "logo.png" (this one is actually different than file2 but has the same name)
}

I tried some combinations of @RequestPart...

When I do:

@RequestPart Map<String, FilePart> files

or

    @RequestPart MultiValueMap<String, FilePart> files

I'm getting:

org.springframework.web.server.ServerWebInputException: 400 BAD_REQUEST "Required request part 'files' is not present"

When I do:

@RequestPart("files") List<FilePart> files

I need to submit files like that:

And then I don't have the information which file is which (if they have the same name):

Finally, I can do:

     @RequestPart("file1") FilePart file1,
     @RequestPart("file2") FilePart file2,
     @RequestPart("file3") FilePart file3

And then it works as expected, but with that, it's possible to submit always only 3 files. I'd like to submit any number of files.

As suggested in comments:

     @PutMapping(value = "/{component}", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
     public void upload(
          @RequestParam Map<String, MultipartFile> files
     ) throws IOException {

and the map is always empty:

See this answer and see whether it helps -> https://stackoverflow.com/questions/4083702/posting-a-file-and-associated-data-to-a-restful-webservice-preferably-as-json#:~:text=Send%20the%20file%20first%20in,an%20ID%20to%20the%20client. — Deviprasad Sharma, Sep 13 '20 at 08:12

Rony Nguyen · Answer 1 · 2020-09-13T09:00:36.467

2

You should use @RequestParam

@PostMapping(value = "/upload", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
public void upload(@RequestParam Map<String, MultipartFile> body) {

}

Then post via form-data media ie:

file1: select file
file2: select file
file3: select file
....

edited Sep 13 '20 at 09:00

answered Sep 13 '20 at 08:24

Rony Nguyen

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In that way, the map is always empty – Mariusz.v7 Sep 13 '20 at 08:50
Did you try it? I just attach an image of the IDE's debugger – Rony Nguyen Sep 13 '20 at 08:54
1

This should work, also passing `MultipartRequest` as parameter to the method and using it's `getFileMap` method works. But you would have to have your files with different keys. – Michał Krzywański Sep 13 '20 at 08:59
@ToànNguyễnHải yes, I've edited my question and added screnshots – Mariusz.v7 Sep 13 '20 at 09:02
@michalk this gave me a clue. I'm using webflux and it's slightly different, but thanks to you I have found a solution. I'll post it in few minutes. Thanks! – Mariusz.v7 Sep 13 '20 at 09:08
@Mariusz.v7 such details should definitely be present in the question :) – Michał Krzywański Sep 13 '20 at 09:09

score 0 · Answer 2 · answered Sep 13 '20 at 09:16

I did not mention I'm using reactive webflux, thus solution posted by @Toàn Nguyễn Hải does not work in my case. I believe it works in non-reactive applications.

For web flux, the following works:

To be fair, I won't accept any answer, because both of them are fine.

Thanks!

Spring Boot, upload any amount of files in REST controller

2 Answers2