ASP.NET AJAX Advance Tips & Tricks （2）

ASP.NET AJAX Advance Tips & Tricks （2）2011-10-18 cnblogs Lance Zhang动态创建Rating控件不能保存ViewState的解决方案

前言：

Rating控件用来标识分级，目前已经有广泛应用。AJAX Control Toolkit中的Rating也做的相当成熟，也算是ASP.NET AJAX扩展中做的最像传统服务端控件的一个了。然而，最近很多朋友抱怨说如果在后台代码中动态创建Rating控件，那么在PostBack发生后，Rating的状态将会丢失（未存入ViewState）。本文介绍两种方法来解决此问题。

问题重现：

如果按以下代码动态创建Rating控件，则点击Button后，Rating选取的值将会丢失：

<%@ Page Language="C#" %><%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %><！DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><script runat="server">protected void Page_Load（object sender, EventArgs e）{AjaxControlToolkit.Rating rt = new Rating（）;Page.Form.Controls.Add（rt）;rt.ID = "LikeRating";rt.MaxRating = 5;rt.CurrentRating = 2;rt.StarCssClass = "ratingStar";rt.WaitingStarCssClass = "savedRatingStar";rt.FilledStarCssClass = "filledRatingStar";rt.EmptyStarCssClass = "emptyRatingStar";}</script><html xmlns="http://www.w3.org/1999/xhtml"><head runat="server"><title></title><style type="text/css">/* Rating */.ratingStar{font-size: 0pt;width: 13px;height: 12px;margin: 0px;padding: 0px;cursor: pointer;display: block;background-repeat: no-repeat;}.filledRatingStar{background-image: url（Images/FilledStar.png）;}.emptyRatingStar{background-image: url（Images/EmptyStar.png）;}.savedRatingStar{background-image: url（Images/SavedStar.png）;}</style></head><body><form id="form1" runat="server"><cc1:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server"></cc1:ToolkitScriptManager><div></div><asp:Button ID="Button1" runat="server" Text="Button" /></form><p>&nbsp;</p></body></html>