在Asp.net MVC 3 web应用程序中，我们会用到ViewData与ViewBag，对比一下：

2021-10-08 21:51:52

ViewData	ViewBag
它是Key/Value字典集合	它是dynamic类型对像
从Asp.net MVC 1 就有了	ASP.NET MVC3 才有
基于Asp.net 3.5 framework	基于Asp.net 4.0与.net framework
ViewData比ViewBag快	ViewBag比ViewData慢
在ViewPage中查询数据时需要转换合适的类型	在ViewPage中查询数据时不需要类型转换
有一些类型转换代码	可读性更好

在Controller中使用ViewData:

public ActionResult UsingViewData()

{

    ViewData["Title"] = " Using ViewData";

    ViewData["ProjectName"] = "My Test Project";

    ViewData["ProjectDescription"] = "This is Test Project to demo Viewdata and viewbag details";

    ViewData["StartDate"] = new DateTime(2011, 1, 1);

    ViewData["TotalPrice"] = 1000;

    ViewData["TotalDays"] = 100;

    Dictionary<string, string> stackholder = new Dictionary<string, string>();

    stackholder.Add("Client","Mr.  Client");

    stackholder.Add("Manager","Mr. Joy");

    stackholder.Add("Team Leader","Mr.Toy");

    stackholder.Add("Sr. developer", "Mr.dojoy");

    stackholder.Add("developer", "Mr. nodoy");

    ViewData["stackholder"] = stackholder;

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

    modules.Add("Admin module");

    modules.Add("ShoppingCart module");

    modules.Add("CMS module");

    ViewData["modules"] = modules;

    return View();

}

对应UsingViewData View的cshtml:

<h1>@ViewData["Title"]</h1>

 <div>

   <div>

    <h2>Project Name : @ViewData["ProjectName"]</h2>

   </div>

   <div>

     ProjectDescription :

     <p>"@ViewData["ProjectDescription"]".</p>

   </div>

   <div>

      Stack Holder :

      <br />

      <ul id="stakholder">

      @foreach ( var stakerholder in ViewData["stackholder"] as Dictionary<string, string> )

      {

    <li>

        @stakerholder.Key &nbsp; : @stakerholder.Value

    </li>

      }

     </ul>

   </div>

   <div>

     Project Details:<br />

     <div>

       module List  :

       <ul id="modulelist">

      @foreach ( var module in ViewData["modules"] as List<string> )

      {

    <li>

        @module

    </li>

      }

     </ul>

     </div>

     Project StartDate : @ViewData["StartDate"]  <br />

     Project TotalPrice: @ViewData["TotalPrice"] <br />

     Project TotaDays  : @ViewData["TotalDays"]

   </div>

 </div>

然后是ViewBag:

public ActionResult UsingViewBag()

{

    ViewBag.Title = " Using ViewBag";

    ViewBag.ProjectName = "My Test Project";

    ViewBag.ProjectDescription = "This is Test Project to demo Viewdata and viewbag details";

    ViewBag.StartDate = new DateTime(2011, 1, 1);

    ViewBag.TotalPrice = 1000;

    ViewBag.TotalDays = 100;

    Dictionary<string, string> stackholder = new Dictionary<string, string>();

    stackholder.Add("Client", "Mr.  Client");

    stackholder.Add("Manager", "Mr. Joy");

    stackholder.Add("Team Leader", "Mr.Toy");

    stackholder.Add("Sr. developer", "Mr.dojoy");

    stackholder.Add("developer", "Mr. nodoy");

    ViewBag.stackholder = stackholder;

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

    modules.Add("Admin module");

    modules.Add("ShoppingCart module");

    modules.Add("CMS module");

    ViewBag.modules = modules;

    return View();

}

对应View UsingViewBag 的cshtml的ViewBag:

<h1>@ViewBag.Title</h1>

 <div>

   <div>

    <h2>Project Name : @ViewBag.ProjectName</h2>

   </div>

   <div>

     ProjectDescription :

     <p>"@ViewBag.ProjectDescription.</p>

   </div>

   <div>

      Stack Holder :

      <br />

      <ul id="stakholder">

      @foreach ( var stakerholder in ViewBag.stackholder )

      {

    <li>

        @stakerholder.Key &nbsp; : @stakerholder.Value

    </li>

      }

     </ul>

   </div>

   <div>

     Project Details:<br />

     <div>

       module List  :

       <ul id="modulelist">

      @foreach ( var module in ViewBag.modules )

      {

    <li>

        @module

    </li>

      }

     </ul>

     </div>

     Project StartDate : @ViewBag.StartDate.ToString("dd-MMM-yyyy") <br />

     Project TotalPrice: @ViewBag.TotalPrice  ₹  <br />

     Project TotaDays  : @ViewBag.TotalDays

   </div>

 </div>

后面是在Controller中使用ViewBag:

public ActionResult UsingViewBagInControlAndViewDataInView()

{

    ViewBag.Title = " Using ViewBag In Control And ViewData In View";

    ViewBag.ProjectName = "My Test Project";

    ViewBag.ProjectDescription = "This is Test Project to demo Viewdata and viewbag details";

    ViewBag.StartDate = new DateTime(2011, 1, 1);

    ViewBag.TotalPrice = 1000;

    ViewBag.TotalDays = 100;

    Dictionary<string, string> stackholder = new Dictionary<string, string>();

    stackholder.Add("Client", "Mr.  Client");

    stackholder.Add("Manager", "Mr. Joy");

    stackholder.Add("Team Leader", "Mr.Toy");

    stackholder.Add("Sr. developer", "Mr.dojoy");

    stackholder.Add("developer", "Mr. nodoy");

    ViewBag.stackholder = stackholder;

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

    modules.Add("Admin module");

    modules.Add("ShoppingCart module");

    modules.Add("CMS module");

    ViewBag.modules = modules;

    return View();

}

在UsingViewBagInControlAndViewDataInView.cshtml中使用ViewData来取值：

<h1>@ViewData["Title"]</h1>

 <div>

   <div>

    <h2>Project Name : @ViewData["ProjectName"]</h2>

   </div>

   <div>

     ProjectDescription :

     <p>"@ViewData["ProjectDescription"]".</p>

   </div>

   <div>

      Stack Holder :

      <br />

      <ul id="stakholder">

      @foreach ( var stakerholder in ViewData["stackholder"] as Dictionary<string, string> )

      {

    <li>

        @stakerholder.Key &nbsp; : @stakerholder.Value

    </li>

      }

     </ul>

   </div>

   <div>

     Project Details:<br />

     <div>

       module List  :

       <ul id="modulelist">

      @foreach ( var module in ViewData["modules"] as List<string> )

      {

    <li>

        @module

    </li>

      }

     </ul>

     </div>

     Project StartDate : @ViewData["StartDate"]  <br />

     Project TotalPrice: @ViewData["TotalPrice"] <br />

     Project TotaDays  : @ViewData["TotalDays"]

   </div>

 </div>

反过来是这样的:

public ActionResult UsingViewDataInControlAndViewBagInView()

{

    ViewData["Title"] = " Using ViewData In Control And ViewBag In View";

    ViewData["ProjectName"] = "My Test Project";

    ViewData["ProjectDescription"] = "This is Test Project to demo Viewdata and viewbag details";

    ViewData["StartDate"] = new DateTime(2011, 1, 1);

    ViewData["TotalPrice"] = 1000;

    ViewData["TotalDays"] = 100;

    Dictionary<string, string> stackholder = new Dictionary<string, string>();

    stackholder.Add("Client", "Mr.  Client");

    stackholder.Add("Manager", "Mr. Joy");

    stackholder.Add("Team Leader", "Mr.Toy");

    stackholder.Add("Sr. developer", "Mr.dojoy");

    stackholder.Add("developer", "Mr. nodoy");

    ViewData["stackholder"] = stackholder;

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

    modules.Add("Admin module");

    modules.Add("ShoppingCart module");

    modules.Add("CMS module");

    ViewData["modules"] = modules;

    return View();

}

在UsingViewDataInControlAndViewBagInView.cshtml 的View中使用ViewBag来取值:

<h1>@ViewBag.Title</h1>

 <div>

   <div>

    <h2>Project Name : @ViewBag.ProjectName</h2>

   </div>

   <div>

     ProjectDescription :

     <p>"@ViewBag.ProjectDescription.</p>

   </div>

   <div>

      Stack Holder :

      <br />

      <ul id="stakholder">

      @foreach ( var stakerholder in ViewBag.stackholder )

      {

    <li>

        @stakerholder.Key &nbsp; : @stakerholder.Value

    </li>

      }

     </ul>

   </div>

   <div>

     Project Details:<br />

     <div>

       module List  :

       <ul id="modulelist">

      @foreach ( var module in ViewBag.modules )

      {

    <li>

        @module

    </li>

      }

     </ul>

     </div>

     Project StartDate : @ViewBag.StartDate.ToString("dd-MMM-yyyy") <br />

     Project TotalPrice: @ViewBag.TotalPrice  ₹  <br />

     Project TotaDays  : @ViewBag.TotalDays

   </div>

 </div>

这样对比看上去会比较清楚一些。在源代码中的ViewBag是这样的属性:

public dynamic ViewBag {

    get {

        if (_dynamicViewData == null) {

            _dynamicViewData = new DynamicViewDataDictionary(() => ViewData);

        }

        return _dynamicViewData;

    }

}

ViewData是：

public ViewDataDictionary ViewData {

    get {

        if (_viewData == null) {

            SetViewData(new ViewDataDictionary());

        }

        return _viewData;

    }

    set {

        SetViewData(value);

    }

}

具体细节在这儿不深入了，这里只是抛砖引玉。希望对您Asp.net MVC开发有帮助。

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