[FIXED] Is it possible to split request params in Spring controllers?

Issue

I have a request like:

example.com/search?sort=myfield1,-myfield2,myfield3

I would like to split those params to bind a List<String> sort in my controller or List<SortParam> where SortParam is the class with fields like: name (String) and ask (boolean).

So the final controller would look like this:

@RequestMapping(value = "/search", method = RequestMethod.GET)
public ResponseEntity<MyResponse> search(@RequestParam List<String> sort) {

    //...
}

or

@RequestMapping(value = "/search", method = RequestMethod.GET)
public ResponseEntity<MyResponse> search(@RequestParam List<SortParam> sort) {

    //...
}

Is there a way to make it?

UPDATE:

The standard way of passing parameters does not satisfy my requirements. I.e. I cannot use sort=myfield1&sort=-myfield2&sort=myfield3. I have to use comma separated names.
Also, I do understand that I can accept @RequestParam String sort in my controller and then split the string inside the controller like sort.split(",") but it also doesn't solve the above problem.

Solution

Yes, you can certainly do that, you're almost there.

@RequestMapping(value = "/search", method = RequestMethod.GET)
public ResponseEntity<MyResponse> participants(@RequestParam("sort") List<String> sort) {

    //...
}

You should now be able to call your service like this (if search is located at your root, otherwise adapt according to your situation):

curl "localhost:8080/search?sort=sortField1&sort=sortField2&sort=sortField3"

Hope this helps!

EDIT Sorry, I have read your comments and what you need is clear to me now. I have created a workaround for you that is almost what you want I think.

So first a SortParams class:

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class SortParams {
  private List<SortParam> sortParamList;

  public SortParams(String commaSeparatedString) {
    sortParamList = Arrays.stream(commaSeparatedString.split(","))
      .map(p -> SortParam.valueOf(p))
      .collect(Collectors.toList());
  }

  public List<SortParam> getSortParamList() {
    return this.sortParamList;
  }

  public enum SortParam {
    FOO, BAR, FOOBAR;
  }
}

Then your controller could look like this:

@RequestMapping(value = "/search", method = RequestMethod.GET)
public ResponseEntity<List<SortParams.SortParam>> search(@RequestParam("sort") SortParams sort) {
    return ResponseEntity.ok(sort.getSortParamList());
}

Now your SortParams object has a list of SortParam:

curl "localhost:8080/search?sort=FOO,BAR"

["FOO","BAR"]

Would something like this fit what you're looking for?

Answered By - Jonck van der Kogel