Spring REST controller with different functions

Question

I have a Spring @RestController for manipulating my Users and I want to have several functions:

/users : GET (returns all users)
/users/:id : GET (returns a user with given ID, default id=1)
/users : POST (inserts a user)
/users/:id : DELETE (deletes a user with given ID)

I started working on it but I'm not sure how to manage the "overlapping" URIs for the same method (e.g. first two cases). Here's what I came with so far:

@RestController
public class UserController {
    @RequestMapping(value = "/users", method = RequestMethod.GET)
    public List<User> getAllUsers() {
        return UserDAO.getAll();
    }

    @RequestMapping(value = "/users", method = RequestMethod.GET)
    public User getUser(@RequestParam(value = "id", defaultValue = "1") int id) {
        return UserDAO.getById(id);
    }
}

This won't work due to "ambiguous mapping" and it's pretty clear to me, but I don't know what to do. Should I change one of the URIs or there is some other way?

Edit: I've also tried changing the second method to:

@RequestMapping(value = "/users/{id}", method = RequestMethod.GET)
public User getUser(@PathVariable("id") int id) {
    return UserDAO.getById(id);
}

Still doesn't work.

If you want to map the desired /users/:id , you should define a @RequestMapping(value = "/users/{id}", method = RequestMethod.GET) and capture that {id} with a @PathVariable int id. — Ali Dehghani
– Ali Dehghani, Commented Nov 29, 2016 at 8:26
What do you mean by Still doesn't work..? If getting any exception, post the full stacktrace... — Ali Dehghani
– Ali Dehghani, Commented Nov 29, 2016 at 8:27
@AliDehghani java.lang.IllegalStateException: Ambiguous mapping. Cannot map 'candidateController' method public java.util.List<model.Candidate> controller.CandidateController.getAllCandidates() to {[/candidates],methods=[GET]}: There is already 'candidateController' bean method public model.Candidate controller.CandidateController.getUser(int) mapped. — vtomic85
– vtomic85, Commented Nov 29, 2016 at 8:27
My mistake... I have changed one file but the error was in another one. I'm a moron :). @AliDehghani if you want to post an answer, I will accept it. — vtomic85
– vtomic85, Commented Nov 29, 2016 at 8:33

Ali Dehghani · Accepted Answer · 2016-11-29 08:42:49Z

3

Your current mapping:

@RequestMapping(value = "/users", method = RequestMethod.GET)
public User getUser(@RequestParam(defaultValue = "1") int id)

Would map to the /users?id=42 not the desired /users/42. If you want to create a mapping for /users/:id endpoint, use the following:

@RequestMapping(value = "/users/{id}", method = RequestMethod.GET)
public User getUser(@PathVariable int id) {
    return UserDAO.getById(id);
}

Also, as of Spring Framework 4.3, you can use new meta annotations to handle GET, POST, etc. methods:

@RestController
@RequestMapping("/users")
public class UserController {
    @GetMapping
    public List<User> getAllUsers() {
        return UserDAO.getAll();
    }

    @GetMapping("{id}")
    public User getUser(@PathVariable int id) {
        return UserDAO.getById(id);
    }
}

answered Nov 29, 2016 at 8:42

Ali Dehghani

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1 Comment

Ali Dehghani Over a year ago

@sura2k Then this may sound interesting, too.

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