Use @RequestParam for multipartfile - right way?

Question

I am developing a spring mvc application and I want to handle the multipart request in my controller. In the request, I pass the MultiPartFile as well, I am currently using @RequestParam to get the paramaeter file, the method looks like

 @RequestMapping(method = RequestMethod.POST) public def save( @ModelAttribute @Valid Product product, @RequestParam(value = "image", required = false) MultipartFile file) { ..... } 

The above code works well in my service and the file gets to the server. Now I saw that in the case of a file, you must use the @RequestPart annotation instead of @RequestParam . Is there something wrong with using @RequestParam for a file? Or could this lead to any error in the future?

Answer 1

There is nothing wrong with using @RequestParam with a Multipart file.

@RequestParam annotation can also be used to bind the part of the "multipart / form-data" request to a method argument that supports the same types of method arguments. The main difference is that when the method argument is not a string, @RequestParam relies on the type of conversion through the registered converter or PropertyEditor while @RequestPart relies on the HttpMessageConverters taking into account the "Content-Type" header of the request part. Probably @RequestParam for use with fields with a value-name, while @RequestPart is most likely to be used with parts containing more complex content (e.g. JSON, XML).

See http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/bind/annotation/RequestPart.html

Answer 2

You can use both annotations, however you can make your choice about them based on how they interpret the internal arguments.

Spring Docs clearly defines the difference between the two:

The main difference is that when the method argument is not a string, @RequestParam relies on type conversion through a registered converter or PropertyEditor , and @RequestPart relies on HttpMessageConverters , taking into account the "Content-Type" header of the request part. @RequestPara is likely to be used with name-value form fields, while @RequestPart is likely to be used with parts containing more complex content (e.g. JSON, XML).