How to handle jackson deserialization error for all kinds of data mismatch in spring boot

Question

I know there is some similar questions here about how to parse ENUM, how to parse customize JSON structure. But here my question is how to just give a better message when the user submit some JSON with is not as expected.

This is the code:

@PutMapping
public ResponseEntity updateLimitations(@PathVariable("userId") String userId,
                                        @RequestBody LimitationParams params) {
  Limitations limitations = user.getLimitations();
  params.getDatasets().forEach(limitations::updateDatasetLimitation);
  params.getResources().forEach(limitations::updateResourceLimitation);
  userRepository.save(user);
  return ResponseEntity.noContent().build();
}

And the request body I expected is like this:

{
  "datasets": {"public": 10},
  "resources": {"cpu": 2}
}

But when they submit something like this:

{
  "datasets": {"public": "str"}, // <--- a string is given
  "resources": {"cpu": 2}
}

The response will show something like this in logs:

400 JSON parse error: Cannot deserialize value of type `java.lang.Integer` from String "invalid": not a valid Integer value; nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type `java.lang.Integer` from String "invalid": not a valid Integer value

at [Source: (PushbackInputStream); line: 1, column: 23] (through reference chain: com.openbayes.api.users.LimitationParams["datasets"]->java.util.LinkedHashMap["public"])

But what I want is a more human readable message.

I tried to use ExceptionHandler for com.fasterxml.jackson.databind.exc.InvalidFormatException but it doesn't work.

Answer 1

You can write a controller advice to catch exceptions and return corresponding error response.

Here is an example of controller advice in spring boot :

@RestControllerAdvice
public class ControllerAdvice {
    @ExceptionHandler(InvalidFormatException.class)
    public ResponseEntity<ErrorResponse> invalidFormatException(final InvalidFormatException e) {
        return error(e, HttpStatus.BAD_REQUEST);
    }

    private ResponseEntity <ErrorResponse> error(final Exception exception, final HttpStatus httpStatus) {
        final String message = Optional.ofNullable(exception.getMessage()).orElse(exception.getClass().getSimpleName());
        return new ResponseEntity(new ErrorResponse(message), httpStatus);
    }
}

@AllArgsConstructor
@NoArgsConstructor
@Data
public class ErrorResponse {
    private String errorMessage;
}

Answer 2

The real exception is org.springframework.http.converter.HttpMessageNotReadableException. Intercept this and it will work.

public ResponseEntity<String> handle(HttpMessageNotReadableException e) {
    return ResponseEntity.badRequest().body("your own message" + e.getMessage());
}