Asp.net MVC中的ViewData与ViewBag

Asp.net MVC中的ViewData与ViewBag

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

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);
    }
}