如何检查ViewBag中的列表是否包含字符串 [英] How to check if a List in a ViewBag contains string

问题描述

我有一个ViewBag，它是我在控制器中创建的列表：

I have a ViewBag that is a list which i create in the controller:

 List<string> listoflists = new List<string>();

然后它会填充一些字符串，例如：

it then gets filled with some string like for example:

listoflists.Add("java");
listoflists.Add("php");
listoflists.Add("C#");

将其添加到ViewBag中：
ViewBag.listoflists = listoflists;

Adding it to the ViewBag: ViewBag.listoflists = listoflists;

然后我想在视图中检查是否包含特定字符串：

i then would like to check in my View if this contains a specific string:

@if(ViewBag.listoflists.contains("java")
{
// do html stuff
}

但是运行此命令时出现以下错误：

but when running this i get the following error:

System.Collections.Generic.List不包含包含的定义

我在做什么错了，还是应该检查列表中是否包含某些内容？

What am i doing wrong, or how should i check if a list contains something in the View?

推荐答案

您可能需要回退到字符串列表：

You might need to cast back to a list of strings:

@if (((IList<string>)ViewBag.listoflists).Contains("java")
{
    // do html stuff
}

还请注意，包含方法以大写字母 C 。

Also notice that the Contains method starts with a capital C.

因此您可以看到在A中使用ViewBag SP.NET MVC是一个完整的废话，导致您的视图中的代码非常丑陋。因此，强烈建议使用视图模型，该模型将包含特定视图的所有必要信息，并且也应进行强类型输入。

So as you can see using ViewBag in ASP.NET MVC is a complete crap leading to very ugly code in your views. For this reason it is strongly recommended to use view models which will contain all the necessary information of a specific view and also being strongly typed.

因此，请切下 ViewBag 废话并开始使用视图模型：

So cut this ViewBag crap and start using view models:

public class MyViewModel
{
    public IList<string> ListOfLists { get; set; }
}

您的控制器操作可以填充并传递给视图：

that your controller action can populate and pass to the view:

public ActionResult Index()
{
    var model = new MyViewModel();
    List<string> listoflists = new List<string>();
    listoflists.Add("java");
    listoflists.Add("php");
    listoflists.Add("C#");
    model.ListOfLists = listoflists;
    return View(model);
}

现在，您可以对该模型有一个强类型化的视图，这将使您避免之前的转换：

and now you can have a strongly typed view to this model which will allow you to avoid the previous casting:

@model MyViewModel

@if (Model.ListOfLists.Contains("java"))
{
    // do html stuff
}

因此，基本上，每次您在ASP.NET MVC应用程序中使用ViewBag / ViewData时，都会立即响起警报，告诉您：伙计，这到底是什么，您做错了。只需使用视图模型即可避免将视图转换为完全不相关的C＃语言构造（如转换和填充）的可恶的混乱。视图用于显示标记。

So basically every time you use ViewBag/ViewData in an ASP.NET MVC application an alarm should immediately ring in your head telling you: Man, what the hell, you are doing it wrong. Just use a view model in order to avoid transforming your views into an abominable mess of completely irrelevant C# language constructs like casting and stuff. Views are meant for displaying markup.

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