Spring Boot Controller Multiple parameters (<List> and multipart file) object

Question

Hello i am looking if i can handle with only one RestController method multiple params... with controllers method it could be done... but i couldnt find project with 2 like that.

@PostMapping(value ="upload")
    public upload(@RequestParam MultipartFile file,@RequestParam List<String> myParams ){
     some code here ....
        return;
    }

I am just wondering if is also a good practise... having two deferent type of objects in same controller and if its possible,,, any idea????

Answer 1

Simple answer: Yes, that's possible.
But as you asked for good practice, here's some context:

It is very helpful to understand how HTTP actually transports data.

If your request uses GET as request method, parameters are added to the URL as a query string. That could look like this: http://example.com/index?param1=value1&param2=value2

In this case, Spring maps the key-value pairs from the query string to your method arguments. But this will only work for text.

If you're using POST , the data is sent inside the request body. How that is encoded depends on the media type of your data. For example, the default media type application/x-www-form-urlencoded would encode the data to the same query string as above.

If you want to upload mixed-type form data like a file/blob along with some textual parameters, your data should be encoded with multipart/form-data .

As long as the request body contains a key-value format, Spring Boot will still be able to distinguish and map the parameters via @RequestParam (If the keys don't differ from your attribute names, you don't even need to assign a name to the value attribute).

I highly recommend you to take a look at the @RequestBody and @RequestPart annotations as i think it often is best practice to use a model class (DTO) for the whole request body (or rather the form, semantically), especially if there are a lot of parameters to process.

Answer 2

You will need to specify the names of the variables.

  @PostMapping(value ="upload")
  public upload(
    @RequestParam(value = "file") MultipartFile file, 
    @RequestParam(value = "myParams") List<String> myParams 
  ){
      some code here ....
      return;
   }