Error uploading multiple files on a multipart request using webflux

[fjavierjimenez]

I'm migrating a rest service developed with spring-boot 2 to use webflux. This rest service is used to upload 2 files using multipart. The first part "file" is usually a PDF file, and the second part "metadata" is a json file with metadata. Here is an example of this webservice:

package com.sngular.controller;

import com.sngular.model.Metadata;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestPart;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

@RestController
public class MultipartController {

    @PostMapping(value = "/upload", consumes = {"multipart/form-data"})
    public String fileUpload(@RequestPart(value = "metadata", required = true) Metadata metadata,
                             @RequestPart(value = "file", required = true) MultipartFile file) {
        return "ok";
    }
}

this REST service works fine when I use the dependency spring-boot-starter-web, when I change it to use spring-boot-starter-webflux It give me the following error when trying to upload the files:

{
    "timestamp": "2018-05-25T20:36:03.505+0000",
    "path": "/upload",
    "status": 415,
    "error": "Unsupported Media Type",
    "message": "Content type 'application/pdf' not supported"
}

this example can be found on the following repository:

https://github.com/fjavierjimenez/springboot-multipart-test

And the postman request Im executing..

Any thoughts on why this gives me the error Content type 'application/pdf' not supported or how to solve this?

[bclozel]

Thanks for getting in touch, but it feels like this is a question that would be better suited to StackOverflow. As mentioned in the guidelines for contributing, we prefer to use GitHub issues only for bugs and enhancements. Feel free to update this issue with a link to the re-posted question (so that other people can find it) or add some more details if you feel this is a genuine bug.

In this case, you should use FilePart instead of MultipartFile - I've checked that replacing this in your project works. This is documented in the Spring Framework reference documentation. If you've got ideas to improve the documentation in any way there, please create an issue against jira.spring.io (project: Spring Framework).

Thanks!