ControllerLinkBuilder.linkTo throws error if called outside of the context of a HTTP request

[nickgrealy]

Current Behaviour

Given the latest spring hateos dependency org.springframework.hateoas:spring-hateoas:0.19.0.RELEASE,

When I attempt to use the ControllerLinkBuilder.linkTo method (outside of the context of a HTTP request),

String url = ControllerLinkBuilder.linkTo(
        methodOn(GreetingController.class).greeting("Nick"))
        .toUri().toString();

Then I get the following exception:

Exception in thread "main" java.lang.IllegalStateException: Could not find current request via RequestContextHolder
    at org.springframework.util.Assert.state(Assert.java:385)
    at org.springframework.hateoas.mvc.ControllerLinkBuilder.getCurrentRequest(ControllerLinkBuilder.java:234)
    at org.springframework.hateoas.mvc.ControllerLinkBuilder.getBuilder(ControllerLinkBuilder.java:186)
    at org.springframework.hateoas.mvc.ControllerLinkBuilderFactory.linkTo(ControllerLinkBuilderFactory.java:117)
    at org.springframework.hateoas.mvc.ControllerLinkBuilder.linkTo(ControllerLinkBuilder.java:135)

Proposed Behaviour

Instead of the exception, I'd expect to receive a relative URL (preferably including the context-path).

e.g. Instead of http://localhost:8080/myappscontext/mycontroller/mymethod/pathvar/foo?a=1, I'd receive /myappscontext/mycontroller/mymethod/pathvar/foo?a=1

Additionally, it'd be excellent if I could specify my own UriComponentsBuilder to be used for building the URI.

e.g.

String url = ControllerLinkBuilder.linkTo(UriComponentsBuilder.
        fromUriString("http://myproxy.com.au/"), 
        methodOn(GreetingController.class).greeting("Nick"))
        .toUri().toString();

Related

The solution proposed should (at least partially) also address these similar issues:

• Support for relative href links? Support for relative href links? #330
• Customize ControllerLinkBuilder How let ControllerLinkBuilder see original request URI? #143
• Expose Configuration for ControllerLinkBuilder Expose Configuration for ControllerLinkBuilder #400

[mahmoudimus]

👍 super useful