Asp.net mvc 2 in action 笔记 -2 View Controller
View
第3、10章
ViewData 和强类型视图
一般情况下，定义presentation model，然后形成强类型视图，可以结合ViewData传递小的片段和简单数据，以增加代码的维护性
presentation model类中可以加入data annotations属性，控制数据的验证
HTML helper类
DisplayFor
DisplayTextFor
EditorFor
CheckBoxFor
DropDownListFor
HiddenFor
LabelFor
ListBoxFor
PasswordFor
RadioButtonFor
TextAreaFor
TextBoxFor
ValidateFor
ValidationMessageFor
以上类都在 System.Web.Mvc ..::. HtmlHelper 类中，MSDN文档可以察看明细，目前这些代码自能手工编写或使用T4自动生成，我估计以后IDE会提供类似WebForm的可视化支持
强类型模板
根据察看和编辑的不同，分为两类
■ Html.Display("Message")
■ Html.DisplayFor(m => m.Message)
■ Html.DisplayForModel()
■ Html.Editor("UserName")
■ Html.EditorFor(m => m.UserName)
■ Html.EditorForModel()
模板查找顺序和自定义
If the template helper method is used inside an area-specific view, these folders include
■ <Area>/<ControllerName>/EditorTemplates/<TemplateName>.ascx (or .aspx)
■ <Area>/Shared/EditorTemplates/<TemplateName>.ascx (or .aspx)
If a template isn’t found in these folders, or if the view isn’t in an area, the default view search locations are used:
■ <ControllerName>/EditorTemplates/<TemplateName>.ascx (or .aspx)
■ Shared/EditorTemplates/<TemplateName>.ascx (or .aspx)
对于察看模板在DisplayTemplates下[第20章有一个使用这个的例子]
Master pages
和Web Form基本类似
Partials
RenderPartial method or the Partial method in a parent view
对于RenderPartial中视图名称在Views目录下的查找顺序：
1 <Area>\<Controller>\<PartialName>.aspx and .ascx
2 <Area>\Shared\<PartialName>.aspx and .ascx
3 \<Controller>\<PartialName>.aspx and .ascx
4 \Shared\<PartialName>.aspx and .ascx
Building query-string parameter lists
处理RouteValueDictionary，使URL象以前的格式如：***?##=##
在MVC中使用Router基本上这种形式不再使用，除非和已有的一些老系统兼容处理可能用到
View Engine
默认是Web Form视图引擎
开源的Spark引擎，具体使用需要遵守这个的语法即可
在MVC 3中已经有Razor视图引擎，微软PI一体化简装包中安装后默认建立的页面使用的就是Razor，毕竟是新加的，没有历史包袱，比Web Form简化
Controller
第4、9、16章
所有的请求都通过这个进行服务
Post-Redirect-Get (PRG)
用于防止表单提交的问题，如果在同一个视图中展现提交结果，客户端刷新时会再次提交从而造成数据的重复和不一致
[HttpPost]
public ActionResult Edit(UserInput input)
{
if (ModelState.IsValid)
{
UpdateUserFromInput(input);
TempData["message"] = "The user was updated";
return RedirectToAction("index");
}
return View(input);
}
private void UpdateUserFromInput(UserInput input)
{
User user = UserRepository.GetByUsername(input.Username);
user.FirstName = input.FirstName;
user.LastName = input.LastName;
UserRepository.Save(user);
}
ActionFilter
This extensibility point allows you to intercept the execution of an action and inject behavior before or after the action is executed. This is similar to aspect-oriented programming, which is a technique for applying cross-cutting concerns to a code base without having lots of duplicate code to maintain.
自己实现只要从ActionFilterAttribute继承即可，如记录日志等
ChildActionOnlyAttribute是框架内置的，比较这个属性的Action，只能在Html.RenderAction的视图中使用
AuthorizeAttribute
Action selectors
The action selector is used to control which action method is selected to handle a particular route.
System.Web.Mvc ..::. ActionMethodSelectorAttribute
System.Web.Mvc ..::. AcceptVerbsAttribute
System.Web.Mvc ..::. HttpDeleteAttribute
System.Web.Mvc ..::. HttpGetAttribute
System.Web.Mvc ..::. HttpPostAttribute
System.Web.Mvc ..::. HttpPutAttribute
System.Web.Mvc ..::. NonActionAttribute
Action results
Custom action results can be used to remove code that’s duplicated across methods and to extract dependencies that can make an action difficult to test.
直接继承ActionResult类
System.Web.Mvc ..::. ActionResult
System.Web.Mvc ..::. ContentResult
System.Web.Mvc ..::. EmptyResult
System.Web.Mvc ..::. FileResult FileContentResult
System.Web.Mvc ..::. HttpUnauthorizedResult
System.Web.Mvc ..::. JavaScriptResult
System.Web.Mvc ..::. JsonResult
System.Web.Mvc ..::. RedirectResult
System.Web.Mvc ..::. RedirectToRouteResult
System.Web.Mvc ..::. ViewResultBase
直接实现一个ActionReslut可以共用，如结果输出CSV文件。
public class CsvActionResult : ActionResult
{
public IEnumerable ModelListing { get; set; }
public CsvActionResult(IEnumerable modelListing)
{
ModelListing = modelListing;
}
public override void ExecuteResult(ControllerContext context)
{
byte[] data = new CsvFileCreator().AsBytes(ModelListing);
var fileResult = new FileContentResult(data, "text/csv")
{
FileDownloadName = "CsvFile.csv"
};
fileResult.ExecuteResult(context);
}
}
主要是在Action方法的返回时实例化以上不同的实现即可。
Routing
URLRewriting
路由注册在Global.asax.cs完成
public static void RegisterRoutes(RouteCollection routes)
{
/* Desired URL schema:
* 1. example.com/ home page
* 2. example.com/privacy static page containing privacy policy
* 3. example.com/widgets show a list of the widgets
* 4. example.com/<widget code> Shows a product detail page for the relevant <widget code>
* 5. example.com/<widget code>/buy Add the relevant widget to the shopping basket
* 6. example.com/basket Shows the current users shopping basket
* 7. example.com/checkout Starts the checkout process for the current user
* 8. example.com/404 show a friendly 404 page
*/
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute("404", "404", new {controller = "Error", action = "NotFound"});
routes.MapRoute("privacy_policy", "privacy", new { controller = "Home", action = "Privacy" });
routes.MapRoute("widget", "{widgetCode}/{action}",
new { controller = "Catalog", action = "Show" },
new { widgetCode = @"WDG-\d{4}" });
routes.MapRoute("widgets", "widgets", new {controller = "Catalog", action = "index"});
routes.MapRoute("catalog", "{action}",
new { controller = "Catalog" },
new { action = @"basket|checkout|index" });
routes.MapRoute(
"Default", // Route name
"{controller}/{action}/{id}", // URL with parameters
new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
);
routes.MapRoute("404-catch-all", "{*catchall}", new {Controller = "Error", Action = "NotFound"});
}
路由处理的优先级从上到下，因此这个的设计是关键
URL生成
Html.ActionLink
Html.RouteLink
Url.Action
…
以上的缺点是参数都是字符串的形式，如果Action换名后，需要手动修改
T4MVC是一个自动化的辅助工具处理URL的生成问题，变成强类型，编译时完成处理。
