MvcUriComponentsBuilder does not expand path variables in controller-level @RequestMapping [SPR-11391]

[spring-projects-issues]

Amr Mostafa opened SPR-11391 and commented

@RequestMapping("/user/{userId}/contacts")
class UserContactController {
    @RequestMapping("/create")
    @ResponseBody
    public String showCreate(@PathVariable Integer userId) {
        return MvcUriComponentsBuilder.fromMethodName(UserContactController.class, "showCreate", userId).build().getPath();
    }
}

Assuming this is running in a servlet mapped at "/", then requesting: http://localhost/user/123/contacts/create is expected to output:

/user/123/contacts/create

But the actual output is:

/user/{userId}/contacts/create

If we change the code to the following:

class UserContactController {
    @RequestMapping("/user/{userId}/contacts/create")
    @ResponseBody
    public String showCreate(@PathVariable Integer userId) {
        return MvcUriComponentsBuilder.fromMethodName(UserContactController.class, "showCreate", userId).build().getPath();
    }
}

Then the expected result is displayed.

---

Affects: 4.0 GA, 4.0.1

[spring-projects-issues]

Amr Mostafa commented

Please note that in the first code snippet, changing build().getPath() to buildAndExpand(userId).getPath() fixes the issue. Therefore I'm no longer sure whether this is a bug or is just incorrect use of the API.

[spring-projects-issues]

Rossen Stoyanchev commented

This has been fixed in master.

changing build().getPath() to buildAndExpand(userId).getPath() fixes the issue

Actually it doesn't since you have to provide a userId method argument (even if null) and then expand it. That duplication should not be necessary. In this example the supplied method argument values should be sufficient to fill in the URI variable values. If the method did not actually have a method argument for a URI variable, then you would need to call .buildAndExpand() in addition.