java - Catch a deserialization exception before a ControllerAdvice

Question

Here is a problem: I have a controller that takes an input model. Lets say

public class AppUserUpdateData {

  @NotNull
  @Size(min = 1, max = 50)
  protected String login;  
  @JsonDeserialize(using = MyDateTimeDeserializer.class)  
  protected Date startWorkDate;
  *************
  other properties and methods
  *************
}

The problem is when I want to restrict a down board of a date I eventually get an HTTP exception 400 without any messages despite I handle this case in my code! here is a controller:

 @RequestMapping(
      value = "/users/{userId}", method = RequestMethod.PUT,
      produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
  public @ResponseBody AbstractSuccessResult updateUser(@PathVariable Long userId,
      @RequestBody AppUserUpdateData  appUserUpdateRequest, HttpServletRequest request) {    
    AbstractSuccessResult response = new AbstractSuccessResult();
    appUserService.updateUser(appUserUpdateRequest, userId);
    return response;
  }

Here is a Deserializer:

public class MyDateTimeDeserializer extends JsonDeserializer<Date> {

  @Override
  public Date deserialize(JsonParser jsonParser, DeserializationContext context)
      throws IOException, JsonProcessingException {
    try {
      return DataTypeHelper.stringToDateTime(jsonParser.getText());
    } catch (MyOwnWrittenException ex) {
      throw ex;
    }
  }  
}

In a DataTypeHelper.stringToDateTime are some validations that are blocking invalid date-strings. And there is a handler for a my exception:

@ControllerAdvice
public class MyExceptionHandler extends ResponseEntityExceptionHandler {

  @ExceptionHandler({ MyOwnWrittenException .class})
  protected ResponseEntity<Object> handleInvalidRequest(RuntimeException exc, 
    WebRequest request) {

    MyOwnWrittenException ex = (MyOwnWrittenException) exc;
    BasicErrorMessage message; = new BasicErrorMessage(ex.getMessage());    
    AbstractUnsuccessfulResult result = new AbstractUnsuccessfulResult(message);
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.APPLICATION_JSON);
    return handleExceptionInternal(exc, result, headers, HttpStatus.BAD_REQUEST, request);
  }
}

The problem is that when an exception in a MyDateTimeDeserializer has been thrown it doesn't falling into a MyExceptionHandler but I cannot understand why? What am I doing wrong? In the response is just an empty response with a code 400(

UPD Thanks to @Joe Doe's answer the problem has been solved. Here is my updated handler:

@Order(Ordered.HIGHEST_PRECEDENCE)    
@ControllerAdvice
public class MyExceptionHandler extends ResponseEntityExceptionHandler {

  @ExceptionHandler({ MyOwnWrittenException .class})
  protected ResponseEntity<Object> handleInvalidRequest(RuntimeException exc, 
    WebRequest request) {

    MyOwnWrittenException ex = (MyOwnWrittenException) exc;
    BasicErrorMessage message; = new BasicErrorMessage(ex.getMessage());    
    AbstractUnsuccessfulResult result = new AbstractUnsuccessfulResult(message);
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.APPLICATION_JSON);
    return handleExceptionInternal(exc, result, headers, HttpStatus.BAD_REQUEST, request);
  }

  @Override
  protected ResponseEntity<Object> handleHttpMessageNotReadable(HttpMessageNotReadableException ex,
      HttpHeaders headers, HttpStatus status, WebRequest request) {
    Throwable cause = ex.getCause();
    String message = null;
    if (cause instanceof JsonMappingException) {
      if (cause.getCause() instanceof MyOwnWrittenException) {
        return handleInvalidRequest((RuntimeException) cause.getCause(), request);
      } else {
        message = cause.getMessage();
      }
    } else {
      message = ex.getMessage();
    }
    AbstractUnsuccessfulResult result = new AbstractUnsuccessfulResult(
        new BasicErrorMessage(message));
    headers.setContentType(MediaType.APPLICATION_JSON);
    return handleExceptionInternal(ex, result, headers, HttpStatus.BAD_REQUEST, request);
  }
}

UPD In my project it doesn't work without annotation @Order(Ordered.HIGHEST_PRECEDENCE) I believe that is because of number of ControllerAdvices in a project

Answer 1

Before updateUser in your controller gets invoked, its arguments have to be resolved. This is where HandlerMethodArgumentResolverComposite comes in, and delegates to one of pre-registered HandlerMethodArgumentResolvers - in this particular case it delegates to RequestResponseBodyMethodProcessor.

By delegating I mean calling the resolver's resolveArgument method. This method indirectly calls the deserialize method from your deserializer, which throws an exception of type MyOwnWrittenException. The problem is that this exception gets wrapped in another exception. In fact, by the time it propagates back to resolveArgument, it's of type HttpMessageNotReadableException.

So, rather than catching MyOwnWrittenException in your custom exception handler, you need to catch exceptions of type HttpMessageNotReadableException. Then, in the method that handles that case, you can check whether the "original" exception was in fact MyOwnWrittenException - you can do that by repeatedly calling the getCause method. In my case (it's probably going to be the same in yours), I needed to call getCause twice to "unwrap" the original exception (HttpMessageNotReadableException -> JsonMappingException -> MyOwnWrittenException).

Note that you can't simply substitute MyOwnWrittenException with HttpMessageNotReadableException in your exception handler since it clashes (at runtime) with another method, specifically designed to handle exceptions of the latter type, called handleHttpMessageNotReadable.

In summary, you can do something like this:

@ControllerAdvice
public class MyExceptionHandler extends ResponseEntityExceptionHandler {

    @Override
    protected ResponseEntity<Object> handleHttpMessageNotReadable(HttpMessageNotReadableException ex, HttpHeaders headers, HttpStatus status, WebRequest request) {
        // ex.getCause().getCause().getClass() gives MyOwnWrittenException
        // the actual logic that handles the exception...
    }
}