如何避免 ViewBag（或 ViewData）而支持模型？

Question

这是一个非常简单的例子，但它应该足以证明我的问题。我需要将模型传递到用户将更新的视图，但视图还需要一些其他数据来创建下拉列表或提供其他信息。

根据下面的代码，我想避免使用 ViewBag/ViewData，所以我是否以某种方式结合 QuestionList和 PasswordLength （出于多余的示例场景而引入）到 ChangeSecurityQuestionModel 中或创建一个新的 ViewModel 或其他对象？

[Authorize]
public ActionResult ChangeSecurityQuestion() {
  var user = Membership.GetUser();
  if (user != null) {
    var model = new ChangeSecurityQuestionModel() {
      PasswordQuestion = user.PasswordQuestion
    };
    ViewBag.QuestionList = new SelectList(membershipRepository.GetSecurityQuestionList(), "Question", "Question");
    ViewBag.PasswordLength = MembershipService.MinPasswordLength;
    return View(model);
  }

  // user not found
  return RedirectToAction("Index");
}

[Authorize]
[HttpPost]
public ActionResult ChangeSecurityQuestion(ChangeSecurityQuestionModel model) {
  if (ModelState.IsValid) {
    var user = Membership.GetUser();
    if (user != null) {
      if (user.ChangePasswordQuestionAndAnswer(model.Password, model.PasswordQuestion, model.PasswordAnswer)) {
        return View("ChangeQuestionSuccess");
      } else {
        ModelState.AddModelError("", "The password is incorrect.");
      }
    }
  }

  // If we got this far, something failed, redisplay form
  ViewBag.QuestionList = new SelectList(membershipRepository.GetSecurityQuestionList(), "Question", "Question");
  ViewBag.PasswordLength = MembershipService.MinPasswordLength;
  return View(model);
}

Answer 1

为什么不将 QuestionList 和 PasswordLength 放入您的 ChangeSecurityQuestionModel 中

var model = new ChangeSecurityQuestionModel() {
      PasswordQuestion = user.PasswordQuestion,
      QuestionList = new SelectList(membershipRepository.GetSecurityQuestionList(), "Question", "Question"),
      PasswordLength = MembershipService.MinPasswordLength;
    };

Answer 2

解决反复出现的“我是否使用 ViewState 还是继续添加到模型”问题的一种替代方法是为 HtmlHelper 创建扩展方法：

public static class HtmlExtensions
{
     public static MvcHtmlString SecurityQuestionDropDown(this HtmlHelper helper)
     {
          return helper.DropDownList(....,new SelectList(membershipRepository.GetSecurityQuestionList(), "Question", "Question"));
     }
}

Answer 3

您可以将 QuestionList 和 PasswordLength 属性添加到 ChangeSecurityQuestionModel 视图模型中。进而：

[Authorize]
public ActionResult ChangeSecurityQuestion() {
    var user = Membership.GetUser();
    if (user != null) {
        var model = new ChangeSecurityQuestionModel() {
            PasswordQuestion = user.PasswordQuestion,
            QuestionList = new SelectList(membershipRepository.GetSecurityQuestionList(), "Question", "Question"),
            PasswordLength = MembershipService.MinPasswordLength
        };
        return View(model);
    }
    // user not found
    return RedirectToAction("Index");
}

[Authorize]
[HttpPost]
public ActionResult ChangeSecurityQuestion(ChangeSecurityQuestionModel model) {
    if (ModelState.IsValid) {
        var user = Membership.GetUser();
        if (user != null) {
            if (user.ChangePasswordQuestionAndAnswer(model.Password, model.PasswordQuestion, model.PasswordAnswer)) {
                return View("ChangeQuestionSuccess");
            } else {
                ModelState.AddModelError("", "The password is incorrect.");
            }
        }
    }
    // If we got this far, something failed, redisplay form
    model.QuestionList = new SelectList(membershipRepository.GetSecurityQuestionList(), "Question", "Question");
    model.PasswordLength = MembershipService.MinPasswordLength;
    return View(model);
}