使用@RequestParam 参数在 Post 方法中映射多个值（多部分数据 + json）

Question

I need to upload from Post request MultipartFile and map a class from json. My controller code looks like this:

 @PostMapping(value = API_FILE_DIRECT_ENDPOINT,
            consumes = {MediaType.MULTIPART_FORM_DATA_VALUE, MediaType.APPLICATION_JSON_VALUE }, produces = MediaType.APPLICATION_JSON_VALUE)
    FileDto create( @RequestParam("file") @NotNull MultipartFile multipartFile,
                   @PathVariable(  IbsAttachmentServiceApi.FILE_TYPE_KEY) String type,
                    @RequestParam("dto") @NotNull ApplyingFileDto applyingFileDto){
    
    FileDto result= process(applyingFileDto, multipartFile);
    
    return result;
    }

when I'm trying to query it from Postman, like this

but it gives me an error

"Failed to convert value of type 'java.lang.String' to required type 'com.domain.ibs.attachment.model.ApplyingFileDto'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'com.domain.ibs.attachment.model.ApplyingFileDto': no matching editors or conversion strategy found"

So it doesn't map ApplyingFileDto class, only if I change it to String, and convert by ObjectMapper explicitly, then it works

@RequestParam("dto") @NotNull String applyingFileDto) ...
ApplyingFileDto mappedDto = objectMapper.readValue(applyingFileDto, ApplyingFileDto.class);

Is there is any way to configure editor to map it after @RequestParam ?

Answer 1

like the error says. You're trying to convert a String value to an ApplyingFileDto Object. The following method to pass objects to a service is to use the @RequestBody annotation. I think that should solve your problem. Give it a try.

Answer 2

It can be because you are unnecessarily including @RequestParam in the controller method. You should use @RequestBody

But before that, Make sure the attributes received as request parameters have perfect getters and setters (eg for attribute bot - setBot) on the object to be mapped.

Add the object as a parameter in the controller method, but do not annotate with @RequestParam. The setter method of the target object will be called for each matching request parameter.

Example -

@PostMapping()
FileDto create(@RequestBody DTO dto) {

}

Answer 3

您有@RequestParam但 dto 不在您的参数中，而是在正文选项卡中

Answer 4

I've found the solution for the answer. It is needed to add @RequestPart annotation instead @RequestParam like this

 @PostMapping(value = API_FILE_DIRECT_ENDPOINT,
            consumes = {MediaType.MULTIPART_FORM_DATA_VALUE, MediaType.APPLICATION_JSON_VALUE }, produces = MediaType.APPLICATION_JSON_VALUE)
    FileDto create( @RequestParam("file") @NotNull MultipartFile multipartFile,
                   @PathVariable(  IbsAttachmentServiceApi.FILE_TYPE_KEY) String type,
                    @RequestPart("dto") @NotNull ApplyingFileDto applyingFileDto){
    
   FileDto result= process(applyingFileDto, multipartFile);
    
    return result;
    }

then reason for is in different type of converters. It is mentioned here

Note that @RequestParam annotation can also be used to associate the part of a "multipart/form-data" request with a method argument supporting the same method argument types. The main difference is that when the method argument is not a String or raw MultipartFile / Part, @RequestParam relies on type conversion via a registered Converter or PropertyEditor while RequestPart relies on HttpMessageConverters taking into consideration the 'Content-Type' header of the request part. RequestParam is likely to be used with name-value form fields while RequestPart is likely to be used with parts containing more complex content eg JSON, XML).

also this example is very useful