(13)使用Ajax Helper 提高用户体验

问题

当你点击链接时,整个的网页都被重新加载。尤其是你仅仅一小点内容需要被更新时,这将被感觉是一个很慢的过程。

解决方案

更新之前创建的HTML.ActionLink 去调用ajax 帮助类。Ajax.ActionLink 仅仅去重新加载那些发生变化的内容。

讨论

MVC提供了几个给力的帮助类。到目前为止,这本书中已经广泛的应用了HTML Helper。在过去创建的所有view中,HTML helper至少都使用过一次。在这个秘方中,我们将使用AjaxHelper类替换掉Book/Index中的HtmlHelper 类。

实现Ajax需要一点额外的设置才可以使用。通常情况下我发现这个额外的工作,可以打消开发人员使用它的念头。我要让大家知道,额外的安装设置是值得的,因为带来的好处是获得了更好的用户体验,这是非常值得努力去做的。

步骤从web.config开始。2个关键的地方要被设置成true. ClientValidationEnabled 和UnobtrusiveJavaScriptEnabled。

译者:原书中代码引入了整个web.config文件。我们只需要到appSettings节点下即可找到这两个keys。

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< appSettings >
   < add key = "webpages:Version" value = "1.0.0.0" />
   < add key = "ClientValidationEnabled" value = "true" />
   < add key = "UnobtrusiveJavaScriptEnabled" value = "true" />
</ appSettings >
 

接下来的步骤是我们要引入几个javascript 文件。我们要在里shared 的layout文件夹里完成这件事,因为几乎我们创建所有的view时都会引用它(布局模板)。在Views/Shared /_Layout.cshtml 文件的<head>标签中。我们引入2个javascript 文件,代码如下:

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< head >
     < title >@ViewBag.Title</ title >
     < link href = "@Url.Content(" ~/Content/Site.css")" rel = "stylesheet" type = "text/css" />
     < script src = "@Url.Content(" ~/Scripts/jquery-1.5.1.min.js")" type = "text/javascript" ></ script >
     < script src = "@Url.Content(" ~/Scripts/jquery.unobtrusive-ajax.min.js")" type = "text/javascript" ></ script >
</ head >
 

这些文件被自动的包含在基础MVC3应用程序中。(译者:你可以从scripts文件夹中找到他们)。以上的步骤完成AJAX的核心配置。接下来,我们要更新Book/index view。在下边的例子里,三个filter link和sortable header link将用Ajax.ActionLink 替换Html.ActionLink.代码如下:

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@model PagedList.IPagedList< MvcApplication.Models.Book >
@if (IsAjax)
{
     Layout = null;
}
< h2 >
     Title</ h2 >
< p >
     @Html.ActionLink("Create New", "Create")
</ p >
< p >
     Show:
     @if (ViewBag.CurrentFilter != "")
     {
         @Ajax.ActionLink("All", "Index",
                             new
                             {
                                 sortOrder = ViewBag.CurrentSortOrder,
                                 Keyword = ViewBag.CurrentKeyword
                             },
                             new AjaxOptions { UpdateTargetId = "main" })
     }
     else
     {
         @:All
         }
     &nbsp; | &nbsp;
     @if (ViewBag.CurrentFilter != "NewReleases")
     {
         @Ajax.ActionLink("New Releases", "Index", new
                         {
                             filter = "NewReleases",
                             sortOrder = ViewBag.CurrentSortOrder,
                             Keyword = ViewBag.CurrentKeyword
                         },
                         new AjaxOptions { UpdateTargetId = "main" })
     }
     else
     {
         @:New Releases
         }
     &nbsp; | &nbsp;
     @if (ViewBag.CurrentFilter != "ComingSoon")
     {
         @Ajax.ActionLink("Coming Soon", "Index", new
                         {
                             filter = "ComingSoon",
                             sortOrder = ViewBag.CurrentSortOrder,
                             Keyword = ViewBag.CurrentKeyword
                         },
                         new AjaxOptions { UpdateTargetId = "main" })
     }
     else
     {
         @:Coming Soon
         }
</ p >
@using (Html.BeginForm())
{
     @:Search: @Html.TextBox("Keyword")< input type = "submit" value = "Search" />
 
}
@Html.Partial("_Paging")
< table >
     < tr >
         < th >
             @Ajax.ActionLink("Title", "Index", new
                             {
                                 sortOrder = ViewBag.TitleSortParam,
                                 filter = ViewBag.CurrentFilter,
                                 Keyword = ViewBag.CurrentKeyword
                             },
                             new AjaxOptions { UpdateTargetId = "main" })
         </ th >
         < th >
             @Ajax.ActionLink("Isbn", "Index", new
                             {
                                 sortOrder = ViewBag.IsbnSortParam,
                                 filter = ViewBag.CurrentFilter,
                                 Keyword = ViewBag.CurrentKeyword
                             },
                             new AjaxOptions { UpdateTargetId = "main" })
         </ th >
         < th >
             Summary
         </ th >
         < th >
             @Ajax.ActionLink("Author", "Index", new
                             {
                                 sortOrder = ViewBag.AuthorSortParam,
                                 filter = ViewBag.CurrentFilter,
                                 Keyword = ViewBag.CurrentKeyword
                             },
                             new AjaxOptions { UpdateTargetId = "main" })
         </ th >
         < th >
             Thumbnail
         </ th >
         < th >
             @Ajax.ActionLink("Price", "Index", new
                             {
                                 sortOrder = ViewBag.PriceSortParam,
                                 filter = ViewBag.CurrentFilter,
                                 Keyword = ViewBag.CurrentKeyword
                             },
                             new AjaxOptions { UpdateTargetId = "main" })
         </ th >
         < th >
             @Ajax.ActionLink("Published", "Index", new
                             {
                                 sortOrder = ViewBag.PublishedSortParam,
                                 filter = ViewBag.CurrentFilter,
                                 Keyword = ViewBag.CurrentKeyword
                             },
                             new AjaxOptions { UpdateTargetId = "main" })
         </ th >
         < th >
         </ th >
     </ tr >
     @foreach (var item in Model)
     {
         < tr >
             < td >
                 @Html.DisplayFor(modelItem => item.Title)
             </ td >
             < td >
                 @Html.DisplayFor(modelItem => item.Isbn)
             </ td >
             < td >
                 @Html.DisplayFor(modelItem => item.Summary)
             </ td >
             < td >
                 @Html.DisplayFor(modelItem => item.Author)
             </ td >
             < td >
                 @Html.DisplayFor(modelItem => item.Thumbnail)
             </ td >
             < td >
                 @Html.DisplayFor(modelItem => item.Price)
             </ td >
             < td >
                 @Html.DisplayFor(modelItem => item.Published)
             </ td >
             < td >
                 @Html.ActionLink("Edit","Edit", new { id = item.ID }) |
                 @Html.ActionLink("Details","Details", new { id = item.ID }) |
                 @Html.ActionLink("Delete","Delete", new { id = item.ID })
             </ td >
         </ tr >
     }
</ table >
@Html.Partial("_Paging")
 

译者:上边代码标绿的地方就是我们更新的地方。

转载于:https://www.cnblogs.com/lyaxx1314/p/3603504.html

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