returning JSON with 401 header

[shaine]

Hi

I have been searching and cannot find how to do this.

I can make my controller return 401 status, using @ResponseStatus, but am unable to return the underlying json. is it even possible to do this? or am I approaching it incorrectly?


@Controller
public class AuthenticationController {

@RequestMapping(method=RequestMethod.GET, value="/AuthenticateUser", produces="application/json")
public @ResponseBody Object authenticateUser(@RequestParam("userId") String userId, @RequestParam("password") String password, @RequestParam("appId") String appId ,@RequestParam("appVersion") String appVersion, @RequestParam("uuid") String uuid) throws Error {
if (userId.equals("dog")) {
return new AuthToken();
} else {
throw new Error();
}
}
}

class AuthToken {
public String authToken = "1234";
}

@ResponseStatus(value=HttpStatus.UNAUTHORIZED)
class Error extends Exception {
public String errorMessage = "an error";
}

[michal.jemala]

Hi Shaine,

in the simplest scenario you can achieve this by creating exception handling method and annotate it as follows:


@Controller
public class AuthenticationController {

@RequestMapping(method=RequestMethod.GET, value="/AuthenticateUser", produces="application/json")
public @ResponseBody Object authenticateUser(
@RequestParam("userId") String userId,
@RequestParam("password") String password,
@RequestParam("appId") String appId,
@RequestParam("appVersion") String appVersion,
@RequestParam("uuid") String uuid) throws Error {
if (userId.equals("dog")) {
return new AuthToken();
} else {
throw new Error();
}
}


@ResponseStatus(HttpStatus.UNAUTHORIZED)
@ExceptionHandler({Error.class})
@ResponseBody
public String handleNotFound(Error e) {
return e.errorMessage;
}

}

class AuthToken {
public String authToken = "1234";
}

class Error extends Exception {
public String errorMessage = "an error";
}


The drawback of this solution is that you can only return String values as there is a limited set of supported return types (see JavaDoc for org.springframework.web.bind.annotation.ExceptionH andler annotation.)

NOTE: If you need more more flixible exception handling consider creating a custom implementation of org.springframework.web.servlet.HandlerExceptionRe solver interface.

Hope this helps.

Michal

[michal.jemala]

Hi Shaine,

the previous solution is a a bit of hack, there is actually a much more clean and elegant solution for your problem. Use org.springframework.http.HttpEntity<T> as a return type as follows



@Controller public class AuthenticationController {
@RequestMapping(method=RequestMethod.GET, value="/AuthenticateUser", produces="application/json")
public @ResponseBody Object authenticateUser(
@RequestParam("userId") String userId,
@RequestParam("password") String password,
@RequestParam("appId") String appId,
@RequestParam("appVersion") String appVersion,
@RequestParam("uuid") String uuid) throws Error {
if (userId.equals("dog")) {
return new AuthToken();
} else {
SomeErrorType errorType = // instantiate and initialize some error type
return new HttpEntity<SomeErrorType>(errorType, HttpStatus.UNAUTHORIZED);
}
}
}
class AuthToken {
public String authToken = "1234";
}
class SomeErrorType {
// some properties of error type
}


The major advantage for this solution is that you can use an arbitrary type for HttpEntity body and do not need to create custom exception handlers.

Cheers,
Michal

[shaine]

Hi Michal

Thanks a lot for the response.

Ideally I would like to not implement this, but I am required to implement an API which expects the 401 + JSON, so I have no choice.

Your solution is exactly what I was looking for, thank you very much