How to throw an exception back in JSON in Spring Boot

Question

I have a Request Mapping -

  @RequestMapping(\"/fetchErrorMessages\")
  public @ResponseBody int fetchErrorMessages(@RequestParam(\"startTime\") String star         


        

Answer 1

This is how I did it in my application:

import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;

@ControllerAdvice
public class ExceptionHandlingControllerAdvice {

   @ExceptionHandler(ExecutionRestrictionViolationException.class)
   public ResponseEntity handleExecutionRestrictionViolationException(ExecutionRestrictionViolationException ex) {
     return response("Invalid Query", ex.getMessage(), HttpStatus.UNPROCESSABLE_ENTITY);
   }

   private static String createJson(String message, String reason) {
    return "{\"error\" : \"" + message + "\"," +
            "\"reason\" : \"" + reason  + "\"}";
   }

   private static ResponseEntity response(String message,
                                               String reason,
                                               HttpStatus httpStatus) {
    String json = createJson(message, reason);
    return new ResponseEntity<>(json, httpStatus);
   }

}

Explanation:

1. You create a controller Advice, mark it with a special annotation and define just like any other bean (in my case it was a java configuration, but it doesn't really matter)

2. For each Exception you would like to handle like this - define a handler that will generate a response in a format you want

3. There is a static method createJson - you can use a different way, it also doesn't matter really.

Now this is only one way to work (its available in more recent spring boot versions) - but there are others:

All the methods I'm aware of (and even more) are listed here.