Allow access to named sections of a multipart request body [SPR-8483]

[spring-projects-issues]

nebhale opened SPR-8483 and commented

Currently when a multipart request is received via a POST call, the only way to reference the sections of that request is by using the @ReqestParam(<name>) annotation to get the body content. The content that you might get is then limited as it can only be converted to simple types (it doesn't go through the ConversionService) and you must do any conversion yourself.

Ideally, it'd be nice to have an @RequestPart(<name>) annotation that would allow you to reference the sections of the request and the values there would go through standard @RequestBody processing for things like ConversionService conversion and @Valid validation.

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Affects: 3.1 M2

Issue Links:

• Throw a more specific exception for a missing part in a multipart request, providing access to the name of the missing part [SPR-8642] #13284 Throw a more specific exception for a missing part in a multipart request, providing access to the name of the missing part

Referenced from: commits 3a87d8e, 3363d05, f4b7cfe

[spring-projects-issues]

Rossen Stoyanchev commented

When sending JSON data using RestTemplate's postForEntity method and a MultiValueMap:

MultiValueMap<String, Object> request = new LinkedMultiValueMap<String, Object>();
request.add("meta-data", new JSONObject().accumulate("version", "testVersion").accumulate("name", "testName"));
request.add("file-data", TEMPLATE_IMAGE);

The signature of the controller method:

@RequestMapping(value = "", method = RequestMethod.POST, consumes = { "multipart/mixed", "multipart/form-data" })
final ResponseEntity<T> create(@RequestPart("meta-data") UnnamedImageInput input, @RequestPart("file-data") MultipartFile file) {

}

Results in the following failure:

java.lang.IllegalArgumentException: Request part named 'meta-data' not found. Available request part names: [file-data]
    at org.springframework.util.Assert.notNull(Assert.java:112)
    at org.springframework.web.multipart.RequestPartServletServerHttpRequest.<init>(RequestPartServletServerHttpRequest.java:54)

On the server side the DefaultMultipartHttpServletRequest contains a multipart file named "file-data", but no multipart file named "meta-data". Instead it does contain a multipart parameter named "meta-data" and it's value is the JSON string.