我在MVC 3中看到了ViewBag。这和MVC 2中的ViewData有什么不同?


当前回答

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

其他回答

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

viewdata:是一个字典,用于存储视图和控制器之间的数据,你需要将视图数据对象转换为视图中相应的模型,以便能够从中检索数据…

ViewBag:是一个动态属性,在它的工作类似于视图数据,但它是更好的,因为它不需要在视图中使用它之前被强制转换为相应的模型…

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:

它使用c# 4.0动态特性。它实现了与viewdata相同的目标,应该避免使用强类型视图模型(与viewdata应该避免的方式相同)。

基本上它取代了魔法字符串:

ViewData["Foo"]

具有神奇属性:

ViewBag.Foo

你没有编译时安全性。

我继续指责微软在MVC中引入了这个概念。

属性的名称区分大小写。

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.