Declarative linking via annotations

[leonard84]

Hi,

are there any plans or interest to add linking via annotations?

I initially used this concept in RESTEasy where it was called @LinkResource. When we switched to Jersey, I missed it so much that I contributed the behavior to Jersey as @ProvideLink.

The basic idea is that you define the links on the methods that they should point to, and say which representations/EntityModels should be enhanced. Doing it this way gets rid of repetitive writing of the same links in multiple methods that return the same model. Furthermore, you don't need to specify the method anymore, since it is already defined due to the presence of the link.

[gregturn]

If you showed us some coded examples, it may better illustrate your desire.

[leonard84]

@gregturn have you looked at the code in the links especially https://eclipse-ee4j.github.io/jersey.github.io/documentation/latest/declarative-linking.html ?

@ProvideLink(value = Order.class,rel = "self",
     bindings = @Binding(name = "orderId", value = "${instance.id}"))
@ProvideLink(value = PaymentConfirmation.class, rel = "order",
     bindings = @Binding(name = "orderId", value = "${instance.orderId}"))
@GET
@Path("/{orderId}")
public Response get(@PathParam("orderId") String orderId)

This code will inject a link into Order with the self relation and also provide a link in PaymentConfirmation with the order relation. The bindings will map the respective fields to the orderId path parameter.

@ProvideLink(value = ProvideLink.InheritFromAnnotation.class, rel = "next",
    bindings = {
        @Binding(name = "page", value = "${instance.number + 1}"),
        @Binding(name = "size", value = "${instance.size}"),
    }, condition = "${instance.nextPageAvailable}")
@ProvideLink(value = ProvideLink.InheritFromAnnotation.class, rel = "prev",
    bindings = {
        @Binding(name = "page", value = "${instance.number - 1}"),
        @Binding(name = "size", value = "${instance.size}"),
    }, condition = "${instance.previousPageAvailable}")
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface PageLinks {
  Class<?> value();
}

This is an advanced scenario, here a meta annotation is created, as you can see there is a level of indirection with @ProvideLink(value = ProvideLink.InheritFromAnnotation.class which will use the value from @PageLinks.
Other than that, this annotation simple provides prev and next links if the respective conditions evaluate to true.