@PostMapping("posts/{id}/comments")
    public Comment addComment(@RequestBody Comment comment, @PathVariable("id") int postId) {

        validateComment(comment, postId);

        comment.setPostId(postId);

        return commentService.createComment(comment);

    }

    private void validateComment(Comment comment, int postId) {
        if (postId < 1) {
            throw new InvalidParameterException();
        }

        if (comment.getId() > 0) {
            throw new InvalidParameterException();
        }

        if (comment.getMessage() == null || comment.getMessage().isEmpty()) {
            throw new InvalidParameterException();
        }
    }

    public Comment createComment(Comment comment) {
        
        if(comment.getPostId()<1) {
            throw new InvalidParameterException();
        }
        
        return commentRepository.save(comment);
    }