ASP.net AJAX Toolkit —— DynamicPopulateExtender

<%@ Page Language="C#" AutoEventWireup="true" Title="DynamicPopulate Sample"%>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajaxToolkit" %>

<script runat="server">
    [System.Web.Services.WebMethod]
    [System.Web.Script.Services.ScriptMethod]
    public static string GetHtml(string contextKey)
    {
        // A little pause to mimic a latent call
        System.Threading.Thread.Sleep(250);

       string value = (contextKey == "U") ?
            DateTime.UtcNow.ToString() :
            String.Format("{0:" + contextKey + "}", DateTime.Now);
        return String.Format("<span style='font-family:courier new;font-weight:bold;'>{0}</span>", value);
    }
</script>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>Dynamic Populate 2</title>
</head>
<body>
    <form id="form1" runat="server">
        <ajaxToolkit:ToolkitScriptManager runat="Server" ID="ScriptManager1" />
        <script  type="text/javascript">
            function updateDateKey(value) {
                var behavior = $find('dp1');
                if (behavior) {
                    behavior.populate(value);
                }
            }
            Sys.Application.add_load(function () { updateDateKey('G'); });
        </script>
        <div class="demoarea">
            <p>
                <asp:Label ID="Label1" runat="server" Text="Label" CssClass="subheading">Time at the server:</asp:Label> 
            </p>
            <p>Choose a date/time format:</p>
            <p>
                <label for="r0">
                    <input type="radio" name="rbFormat" id="r0" value='G'
                        onclick="updateDateKey(this.value);" checked="checked" />Normal
                </label>
                <br />
                <label for="r1">
                    <input type="radio" name="rbFormat" id="r1" value='d'
                        onclick="updateDateKey(this.value);" />
                        Short Date
                </label>
                <br />
                <label for="r2">
                    <input type="radio" name="rbFormat" id="r2" value='D'
                        onclick="updateDateKey(this.value);" />Long Date
                </label>
                <br />
                <label for="r3">
                    <input type="radio" name="rbFormat" id="r3" value='U'
                        onclick="updateDateKey(this.value);" />UTC Date/Time
                </label>
                <br />
            </p>
            <br />
            <asp:Panel ID="Panel1" runat="server" CssClass="dynamicPopulate_Normal" />
            <ajaxToolkit:DynamicPopulateExtender ID="dp1" 
                    runat="server"
                    TargetControlID="Panel1"
                    PopulateTriggerControlID="Label1"
                    ServiceMethod="GetHtml" />
        </div>
    </form>
</body>
</html>

要特别注意添加DynamicPopulateExtender的PopulateTriggerControlID 属性。如果没有添加PopulateTriggerControlID 属性，页面会一直报错——

Can't find control with ID ''。

”

ASP.net AJAX Toolkit —— DynamicPopulateExtender

Can't find control with ID ''。

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