MVC在ModelState.IsValid = false上设置Html.DropdownList [英] MVC setting up Html.DropdownList on ModelState.IsValid = false

问题描述

在保持可维护代码的同时，这总是让我感到困惑的是最好的方法.下面的代码为付款网关表单设置了月份和年份的列表，然后将其分配给类型为List<SelectListItem>的变量.

This is something that has always puzzled me as to the best way round, while keeping maintainable code. The below code sets up a list of months and years for a payment gateway form, before assigning these to a variable of type List<SelectListItem>.

初始动作

PayNowViewModel paymentGateway = new PayNowViewModel();
List<SelectListItem> paymentGatewayMonthsList = new List<SelectListItem>();
List<SelectListItem> paymentGatewayYearsList = new List<SelectListItem>();

for (int i = 1; i <= 12; i++)
{
    SelectListItem selectListItem = new SelectListItem();
    selectListItem.Value = i.ToString();
    selectListItem.Text = i.ToString("00");

    paymentGatewayMonthsList.Add(selectListItem);
}

int year = DateTime.Now.Year;
for (int i = year; i <= year + 10; i++)
{
    SelectListItem selectListItem = new SelectListItem();
    selectListItem.Value = i.ToString();
    selectListItem.Text = i.ToString("00");

    paymentGatewayYearsList.Add(selectListItem);
}

paymentGateway.ExpiryMonth = paymentGatewayMonthsList;
paymentGateway.ExpiryYear = paymentGatewayYearsList;

return View(paymentGateway);

这是一段相当不错的代码，我发现自己以类似的格式重复了这段代码，以在ModelState.IsValid为false且我想返回到视图以供用户更正的情况下重新设置下拉列表选项.有错误.

It's a fair bit of code, and I find myself repeating this code, in similar formats to re-setup the dropdown lists options should the ModelState.IsValid be false and I want to return back to the view for the user to correct there mistakes.

HttpPost操作-代码

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult ConfirmPayment(PayNowViewModel paymentGatewayForm, FormCollection form)
{
    if (ModelState.IsValid)
    {
        // Post processing actions...
        return View();
    }
    else
    {
        for (int i = 1; i <= 12; i++)
        {
            SelectListItem selectListItem = new SelectListItem();
            selectListItem.Value = i.ToString();
            selectListItem.Text = i.ToString("00");

            paymentGatewayMonthsList.Add(selectListItem);
        }

        int year = DateTime.Now.Year;
        for (int i = year; i <= year + 10; i++)
        {
            SelectListItem selectListItem = new SelectListItem();
            selectListItem.Value = i.ToString();
            selectListItem.Text = i.ToString("00");

            paymentGatewayYearsList.Add(selectListItem);
        }

        form.ExpiryMonth = paymentGatewayMonthsList;
        form.ExpiryYear = paymentGatewayYearsList;

        return View("MakePayment", form);
    }
}

集中此下拉设置代码，使其仅集中在一个地方的最佳方法是什么?目前，您会看到很大一部分(for循环)，恰好重复了两次.具有功能的基本控制器?还是像上面那样重新设置更好?

What's the best way to centralise this dropdown setup code so its only in one place? At present you'll see a large proportion (the for loops), is exactly repeated twice. A base controller with function? Or is it better to re-setup like the above?

任何建议，不胜感激！ 迈克.

Any advice appreciated! Mike.

推荐答案

向控制器添加私有方法(以下代码假定ExpiryMonth和ExpiryYear属性为IEnumerable<SelectListItem>，这是DropDownListFor()的全部内容)方法要求)

Add a private method to your controller (the following code assumes your ExpiryMonth and ExpiryYear properties are IEnumerable<SelectListItem> which is all that the DropDownListFor() method requires)

private void ConfigureViewModel(PayNowViewModel model)
{
  model.ExpiryMonth = Enumerable.Range(1, 12).Select(m => new SelectListItem
  {
    Value = m.ToString(),
    Text = m.ToString("00")
  });
  model.ExpiryYear = Enumerable.Range(DateTime.Today.Year, 10).Select(y => new SelectListItem
  {
    Value = y.ToString(),
    Text = y.ToString("00")
  });
}

然后在GET方法中

public ActionResult ConfirmPayment()
{
  PayNowViewModel model = new PayNowViewModel();
  ConfigureViewModel(model);
  return View(model);
}

以及POST方法中

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult ConfirmPayment(PayNowViewModel model)
{
  if (!ModelState.IsValid)
  {
    ConfigureViewModel(model);
    return View(model);
  }
  .... // save and redirect (should not be returning the view here)
}

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