我能建议你不要用吗?

如果你想“发送”数据到你的屏幕上，发送一个强类型对象(又名ViewModel)，因为它更容易测试。

如果你绑定到某种类型的“模型”，并拥有随机的“viewbag”或“viewdata”项，那么这会使自动化测试变得非常困难。

如果您正在使用这些，请考虑如何重构并仅使用ViewModels。

ViewBag和ViewData是ASP中用来将信息从控制器传递到视图的两种方式。净MVC。使用这两种机制的目的是提供控制器和视图之间的通信。两者的生命周期都很短，即一旦重定向发生，两者的值都将变为null，即一旦页面从源页面(我们在其中设置了ViewBag或ViewData的值)重定向到目标页面，ViewBag和ViewData都将变为null。

尽管ViewBag和ViewData有这些相似之处，但如果我们讨论它们的实现，它们是两个不同的东西。区别如下:

1)。如果我们分析这两个实现，我们会发现ViewData是一个字典数据结构——对象字典从viewdatdictionary派生而来，可以使用字符串作为这些值的键来访问，而ViewBag利用了c# 4.0中引入的动态特性，并且是一个动态属性。

2)。当从ViewData中访问值时，我们需要类型转换值(数据类型)，因为它们存储为ViewData字典中的对象，但如果我们在ViewBag中访问值，则不需要这样做。

3)。在ViewBag中，我们可以像这样设置值:

      ViewBag.Name = "Value"; 

并可访问如下:

          @ViewBag.Name

而在ViewData的情况下，值可以设置和访问如下: 设置ViewData的方法如下:

ViewData["Name"] = "Value";

像这样获取价值

 @ViewData["Name"] 

详情请按此处:

下面是关于ViewData, ViewBag, TempData和Session的点对点差异。 信贷/ askforprogram复制。在这里，遵循我没有提到的代码示例的链接。

ViewData in MVC ViewData is property of ControllerBase class. ViewData is a type of dictionary object. ViewData is key-value dictionary collection. ViewData was introduced in MVC 1.0 version. ViewData works with .Net framework 3.5 and above. Need to do type conversion of code while enumerating. ViewData object keeps data only for current request. ViewBag in MVC ViewBag is property of ControllerBase class. ViewBag is a type of dynamic object. ViewBag is a type of object. ViewBag was introduced in MVC 3.0 version. ViewBag works with .Net framework 4.0 and above. ViewBag uses property and handles it, so no need to do type conversion while enumerating. ViewBag object keeps data only for current request. TempData in MVC TempData is property of ControllerBase class. TempData is a type of dictionary object. TempData is key-value dictionary collection. TempData was introduced in MVC 1.0 version. TempData works with .Net framework 3.5 and above. Need to do type conversion of code while enumerating. TempData object is used to data between current request and subsequent request. Session in MVC Session is property of Controller(Abstract Class). Session is a type of HttpSessionStateBase. Session is key-value dictionary collection. Session was introduced in MVC 1.0 version. TempData works with .Net framework 1.0 and above. Need to do type conversion of code while enumerating. Session object keeps data for all requests. Valid for all requests, never expires.

所有的答案都表明ViewBag和/或ViewData是将数据从控制器传递到视图，这是错误的信息。两者都非常有用，可以将数据从视图传递到布局或局部视图(或ViewComponents等)。它不是控制器专属的。

默认的asp.net示例在布局页面中有:

<title>@ViewData["Title"] - MyApp</title>

在任何情况下

ViewData["Title"] = "Details";

然后，问这个问题:“ViewBag和ViewData之间有什么区别?”

最显著的区别是ViewData是一个强类型字典 ViewBag是一个动态类型。

注意里面的数据IS the SAME

ViewData["Title"] = "MyTitle";
ViewBag.Title; // returns "MyTitle";

什么时候用这个或那个?

ViewBag doesn't support not valid C# names. you can't access ViewData["Key With Space"] with ViewBag ViewBag.Something is dynamic and you may have problems when calling methods (like extension methods) that needs to know the exact parameter at compile time. ViewBag can check for nulls syntactical cleaner: ViewBag.Person?.Name ViewData have all the properties of a Dictionary like ContainsKey, Add, etc. so you can use ViewData.Add("somekey", "somevalue") keep in mind it might throw exceptions. Using ViewData on views needs TypeCasting while ViewBag don't.

知道了细微的差别，使用其中一种更像是一种口味偏好。

通常你可以想到ViewBag。ViewData别名的任意键["AnyKey"]

Although you might not have a technical advantage to choosing one format over the other, you should be aware of some important differences between the two syntaxes. One obvious difference is that ViewBag works only when the key you’re accessing is a valid C# identifi er. For example, if you place a value in ViewData["Key With Spaces"], you can’t access that value using ViewBag because the code won’t compile. Another key issue to consider is that you cannot pass in dynamic values as parameters to extension methods. The C# compiler must know the real type of every parameter at compile time in order to choose the correct extension method. If any parameter is dynamic, compilation will fail. For example, this code will always fail: @Html.TextBox("name", ViewBag.Name). To work around this, either use ViewData["Name"] or cast the va

这里ViewData和ViewBag都用于将数据从控制器传递到视图。

1. 显示数据

——ViewData是字典对象，从ViewDataDictonary类派生。

数据只允许一个请求，当页面重定向发生时ViewData值被清除。

——ViewData值必须在使用前输入。

示例:在控制器中

public ActionResult PassingDatatoViewWithViewData()
{
      ViewData["Message"] = "This message shown in view with the ViewData";
      return View();
}

在视图

@ViewData["Message"];

——ViewData是Key和Value这样的一对，Message是Key，在倒逗号中Value是Value。

数据是简单的，所以我们不能在这里使用类型转换，如果数据是复杂的，那么使用类型转换。

public ActionResult PassingDatatoViewWithViewData()
{
      var type= new List<string>
    {
        "MVC",
        "MVP",
        "MVVC"
    };
    ViewData["types"] = type;
    return View();
}

在视图中数据可以提取为

<ul>
        @foreach (var items in (List<string>)ViewData["types"])
        {
         <li>@items</li>
        }
  </ul>

2. ViewBag

——ViewBag使用动态特性。ViewBag包装了ViewData。

—在ViewBag类型铸造是必需的。

——与ViewData相同，如果重定向发生，值将变为null。

例子:

public ActionResult PassingDatatoViewWithViewBag()
{
          ViewData.Message = "This message shown in view with the ViewBag";
          return View();
}

在视图

@ViewBag.vbMessage

—对于复杂类型使用ViewBag

public ActionResult PassingDatatoViewWithViewBag()
{
          var type= new List<string>
        {
            "MVC",
            "MVP",
            "MVVC"
        };
        ViewBag.types = type;
        return View();
 }

在视图中数据可以提取为

<ul>
       @foreach (var items in ViewBag.types)
       {
         <li>@items</li>
       }
</ul>

主要的区别是ViewBag不需要类型转换，而ViewData需要类型转换。