Spring WebFlux - Content type 'application/xml' not supported for bodyType=org.springframework.web.multipart.MultipartFile

Question

I am using spring-webflux and want to upload files .... everything works great with just spring-web but when it comes to webflux i have not a clue what's wrong .

Be careful in the difference ... i am using :

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-webflux</artifactId>
    </dependency>

So let's say we have the below @RestController , for Spring Web it works like charm:

@PostMapping(value = "/uploadFile")
public Response uploadFile(@RequestParam("file") MultipartFile file) {

}

Now trying the same with Spring-webflux produces the below error :

{
    "timestamp": "2019-04-11T13:31:01.705+0000",
    "path": "/upload",
    "status": 400,
    "error": "Bad Request",
    "message": "Required MultipartFile parameter 'file' is not present"
}

---

I found from a random stackoverflow question that i have to use @RequestPart instead of @RequestParam but now i am getting the below error and i don't have a clue why this happens ?

The error is the below :

{
    "timestamp": "2019-04-11T12:27:59.687+0000",
    "path": "/uploadFile",
    "status": 415,
    "error": "Unsupported Media Type",
    "message": "Content type 'application/xml' not supported for bodyType=org.springframework.web.multipart.MultipartFile"
}

Even with .txt files is producing the same error :

{
    "timestamp": "2019-04-11T12:27:59.687+0000",
    "path": "/uploadFile",
    "status": 415,
    "error": "Unsupported Media Type",
    "message": "Content type 'application/xml' not supported for bodyType=org.springframework.web.multipart.MultipartFile"
}

Below is the Postman Configuration which is pretty straight forward , i am just calling with a post request and modified only the body as shown in the picture .

By the way i have added the needed properties on application.properties too :)

## MULTIPART (MultipartProperties)
# Enable multipart uploads
spring.servlet.multipart.enabled=true
# Threshold after which files are written to disk.
spring.servlet.multipart.file-size-threshold=2KB
# Max file size.
spring.servlet.multipart.max-file-size=200MB
# Max Request Size
spring.servlet.multipart.max-request-size=215MB

Answer 1

As documentation sais :

The DefaultServerWebExchange uses the configured HttpMessageReader<MultiValueMap<String, Part>> to parse multipart/form-data content into a MultiValueMap.

To parse multipart data in streaming fashion, you can use the Flux returned from an HttpMessageReader instead.

With few words you need to do something like this:

    @RequestMapping(path = "/uploadFile", method = RequestMethod.POST, 
        consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    public Flux<String> uploadFile(@RequestBody Flux<Part> parts) {
    //...
    }

Look at this example