ASP.NET MVC学习笔记-Controller与View传值

在asp.net2.0的网页开发模式下，我们一般通过直将访问页面控件， 将值写入到页面， 但在Asp.net MVC模式下，已不能在Controller中再去访问页面控件了，要如何才能给View页面传值呢？

在Controller中有两个字典(ViewData和TempData)来实现View之间的值传递, 在ControllerBase类声明中我们就可以看到：

namespace System.Web.Mvc
{
// 摘要:
//     Represents the base class for all MVC controllers.
public abstract class ControllerBase : MarshalByRefObject, IController
{
protected ControllerBase();
// 摘要:
//     Gets or sets the controller context.
public ControllerContext ControllerContext { get; set; }
//
// 摘要:
//     Gets or sets the temporary data.
public TempDataDictionary TempData { get; set; }
//
// 摘要:
//     Gets or sets a value indicating whether the request is valid.
public bool ValidateRequest { get; set; }
//
// 摘要:
//     Gets or sets the value provider.
public IDictionary<string, ValueProviderResult> ValueProvider { get; set; }
//
// 摘要:
//     Gets or sets the view data.
public ViewDataDictionary ViewData { get; set; }
// 摘要:
//     Executes the specified request context.
//
// 參數:
//   requestContext:
//     The request context.
protected virtual void Execute(RequestContext requestContext);
//
// 摘要:
//     Executes the core.
protected abstract void ExecuteCore();
//
// 摘要:
//     Initializes the specified request context.
//
// 參數:
//   requestContext:
//     The request context.
protected virtual void Initialize(RequestContext requestContext);
}
}

而在ViewResultBase中我们同样可以看到它也含有这两个字典存在:

// 摘要:
//     Base class used to supply the model to the view and then render the view
//     to the response.
public abstract class ViewResultBase : ActionResult
{
protected ViewResultBase();
// 摘要:
//     Gets or sets the System.Web.Mvc.TempDataDictionary for this result.
public TempDataDictionary TempData { get; set; }
//
// 摘要:
//     Gets or sets the System.Web.Mvc.IView that is rendered to the response.
public IView View { get; set; }
//
// 摘要:
//     Gets or sets the view data System.Web.Mvc.ViewDataDictionary for this result.
public ViewDataDictionary ViewData { get; set; }
//
// 摘要:
//     Gets or sets the view engines (System.Web.Mvc.ViewEngineCollection) associated
//     with this result.
public ViewEngineCollection ViewEngineCollection { get; set; }
//
// 摘要:
//     Gets or sets the name of the view to be rendered.
public string ViewName { get; set; }
// 摘要:
//     When called by the action invoker, renders the view to the response.
//
// 參數:
//   context:
//     The context within which the result is executed.
public override void ExecuteResult(ControllerContext context);
//
// 摘要:
//     When overridden, returns the System.Web.Mvc.ViewEngineResult used to render
//     the view.
//
// 參數:
//   context:
//     The context.
//
// 傳回:
//     The view engine.
protected abstract ViewEngineResult FindView(ControllerContext context);
}

由此可以看出,Controller通过ViewData,TempData传通到ViewResult中， 然后再由ViewResult传递到ViewPage中来实现值传递的。

1.TempData和ViewData的应用

ViewData只对当前Action有效，而TempData有点类似于Session, 可在所有View访问， 一般用于记录错误信息.

Action代码:

public ActionResult Index()
{
ViewData["Message"] = "Welcome to ASP.NET MVC!";
return View();
}

页面代码：

<h2><%= Html.Encode(ViewData["Message"]) %></h2>

TempData使用方式与View使用方式一致.

2. ViewData与TextBox实现自动绑定

利用HtmlHelper创建TextBox时，使用名称与ViewData中的Key一致， 就会自动实现值绑定,如:

Name:<%= Html.TextBox("name") %>

名称不相同的情况下，也可以利用TextBox的重载传值:

Name:<%= Html.TextBox("name", ViewData["Nm"]) %>

3.View向Controller传值

1). 利用Action参数

<form name="form1" action="/Home/Index" method="post">
Name:<input type="text" name="name" /><br />
Sex: <input type="text" name="sex" />
<input type="submit" value="submit" />
</form>
<%
if (ViewData["name"] != null)
{
Response.Write("your name is:" + ViewData["name"] + ",  your sex is:" + ViewData["sex"]);
}
%>
Action代码:
public ActionResult Index(string name, string sex)
{
ViewData["Message"] = "Welcome to ASP.NET MVC!";
ViewData["name"] = name;
ViewData["sex"] = sex;
return View();
}

2).利用Request.From或Request.QueryString

public ActionResult Index()
{
ViewData["Message"] = "Welcome to ASP.NET MVC!";
ViewData["name"] = Request.Form["name"];
ViewData["sex"] = Request.Form["sex"];
return View();
}

3). 利用FormCollection获取页面值

public ActionResult Index(FormCollection form)
{
ViewData["Message"] = "Welcome to ASP.NET MVC!";
User u=new User();
u.Name = form["Name"];
u.Password = form["Password"];
return View(u);
}

4.传递强类型

1).添加一个传递强类型Model的Action

public ActionResult ModelDemo()
{
User u= new User() { UserName="li", Password="abcde" };
return View(u);
}

对应的View也需要继随于ViewPage<User>, 对应代码如下:

<p>
<%User u = (User)ViewData.Model;%>
UserName:
<%= Html.Encode(u.UserName) %>
</p>
<p>
Password:
<%= Html.Encode(u.Password) %>
</p