ViewData与ViewBag比较
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 : @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 : @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 : @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 : @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); } }