String Hateoas link to a void method

Question

I am working with Spring Hateoas for HAL standards in HTTP response. I have a HTTP DELETE method in my controller which returns nothing (void). And in the response for same entity I want to provide a link to delete a resource. I tried to do with following code but it gives error

Cannot resolve method linkTo(void)

    resource.add(linkTo(
            methodOn(DokumenteController.class)
                    .loeschenEinDokument(filenetDokumentZuordnung.getDokumentId()))
                            .withRel("download"));

Is there any way I can add a link to a method which returns void?

Onions

See #30574931, could help, although the single answer hasn't been accepted nor upvoted... – Powerboat

This is a very nice Github link to look at. The short answer is: it cannot be done directly. The answer provided by 'a better olive' is the best you can do. github.com/spring-projects/spring-hateoas/issues/1173 – Serval

Answer 1

Don't return void. Return ResponseEntity<Void> instead.

Chances are, that you have to set some headers anyway, even if you don't return a message body. Or you want to set a status code.

If your controller has an appropriate request mapping you can also do the following:

 resource.add(linkTo(DokumenteController.class)
             .slash(filenetDokumentZuordnung.getDokumentId())
             .withRel("download"));

Giles

It might be worth reformatting the response to emphasize that there are two answers here, I found the 2nd to be a better fit for my case. – Awlwort

Answer 2

I doubt it's possible to link to a DELETE route.

Hateoas is allowing you to discover your REST API, but a REST API means that in order to delete the document available at /document/42 you should call the same route, but with a DELETE method.

Basically, you don't have to make a link to your deletion method, because it is implicit that this is the way to delete your document.

Riehl

It makes sense to have separate links for each CRUD operation to give the client information about if a specific operation is allowed or not. If the client receives a href with relation name 'deleteDocument', delete would be allowed. If not, it is not allowed. – Moreville