使用空合并运算符重用的原子代码块

Posted 2021-02-26

A style of code reuse. Breaking methods (in this case MVC controller) into very small reusable atomic chunks that either perform an operation then return an ActionResult OR return null, then using with the null-coalescing operator.

public ActionResult AddComment(CommentAddModel model)
{
    return 
        IfNotValidModelStateViewContent(model) ?? 
        IfNotKnownHumanViewCommentCaptcha(model) ?? 
        AddCommentThenViewReciept(model);
}
 
private ActionResult IfNotValidModelStateViewContent(CommentAddModel model)
{
    var contentItem = _repository.FindById<ContentItem>(model.Id);
    return !ModelState.IsValid ? View(contentItem, model) : null;
}
 
private ActionResult IfNotKnownHumanViewCommentCaptcha(CommentAddModel model)
{
    var sessionId = _httpContextProvider.Current.Session.SessionID;
    var isKnownHuman = _captchaService.IsKnownHuman(sessionId);
    return !isKnownHuman ? ViewCommentCaptcha(sessionId, model) : null;
}
 
private ActionResult AddCommentThenViewReciept(CommentAddModel model)
{
    var contentItem = _repository.FindById<ContentItem>(model.Id);
    _commentService.AddCommentToEntity(contentItem, model.Body, model.AuthorName, model.AuthorEmailAddress);
    _repository.Save(contentItem);
    return ViewCommentReceipt(contentItem.Url);
}