Exception Handling

We recently introduced the TaskNotFoundException. Let's now handle it in the global exception handler.

Update the Global Exception Handler

When a TaskNotFoundException bubbles up to the presentation layer we want to return a standard, helpful error message and an HTTP 400 BAD REQUEST status code.

Let's add this handler to the GlobalExceptionHandler class:

  /**
   * Handles the TaskNotFoundException, returning a standardised error
   * response and an HTTP 400.
   * This exception is thrown when the specified task is not found.
   *
   * @param ex The TaskNotFoundException.
   * @return The standardised error and an HTTP 400.
   */
  @ExceptionHandler({TaskNotFoundException.class})
  public ResponseEntity<ErrorResponseDto> handleExceptions(
    TaskNotFoundException ex) {

    // Create an ErrorResponseDto using a templated error message.
    ErrorResponseDto errorResponseDto = new ErrorResponseDto(
        String.format("Task with ID '%s' not found", ex.getId())
    );

    // Return the ErrorResponseDto with status HTTP 400 BAD REQUEST.
    return new ResponseEntity<>(errorResponseDto, HttpStatus.BAD_REQUEST);
  }

With the TaskNotFoundException handled, let's now test the update task feature in the UI!

Summary

Added handling for the TaskNotFoundException class.