Spring data REST content negotiation

Question

I have an annotated RepositoryRestResource for domain objects whose fields also contain binary data (images.) The Spring Rest machinery will create nice RESTful links for these fields, but I would also like to introduce a handler that returns the bare binary when browsers send an "image/*" accept header.

I could overlay a controller on the same paths, but it's brittle and I'd rather write a strategy class for this.

Possible? Any idea where to plug it in the Spring plumbing?

TIA, Edoardo

Have you considered not overriding/overloading the controller to the *//* endpoint, and simply adding another endpoint, *//binary* (or whatever name you see fit) that returns the binary data of a resource? — Marc Tarin, Apr 11 '16 at 08:06

score 0 · Accepted Answer · edited May 23 '17 at 10:33

Using the @RepositoryRestController annotation "properly", you should be able to restrict the controller override to the "image/*" only.

Say you have a simple domain object model (getters/setters and a some annotations omitted...)

public class Item {
    @Id
    private String id;
    private String name;
}

Let's override the controller for image/* only

@RepositoryRestController
@ResponseBody
public class ItemRepositoryRestController {

    @Autowired
    private ItemRepository repository;

    @RequestMapping(value = "/items/{id}", method = RequestMethod.GET,
                    produces = "image/*")
    public Item getItem(@PathVariable(value = "id") String id)
    {
        Item item = repository.findOne(id);
        /* do some magic with your item */

        return item;
    }

Obviously, no image/* data is returned here - you'll actually get a 400 error - but you do only get to this controller if asking if accepting image/*, while going through the automagic Spring Rest Controller when not asking for image/* if and only if you use @RequestMapping at the method level.

I haven't been to the point where I return raw binary data, you may have to use the HttpServletResponse directly as shown here. Or perhaps you already have an answer for this since in your comment you mention having added another resource path already (in which case I'm interested in how you return the raw data).

I accepted the answer although I'm now having problems with choosing a correct produces clause. Everything I try seems to cause an HTTP 406. — Eddy, Apr 14 '16 at 13:32

Spring data REST content negotiation

1 Answers1