我试图创建一个简单的用户控件,这是一个滑块。当我添加一个AjaxToolkit SliderExtender到用户控件时,我得到这个(*&$#()@#错误:

Server Error in '/' Application. The Controls collection cannot be modified because the control contains code blocks (i.e. `<% ... %>`). Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException: The Controls collection cannot be modified because the control contains code blocks (i.e. `<% ... %>`).

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[HttpException (0x80004005): The Controls collection cannot be modified because the control contains code blocks (i.e. `<% ... %>`).]    System.Web.UI.ControlCollection.Add(Control child) +8677431    AjaxControlToolkit.ScriptObjectBuilder.RegisterCssReferences(Control control) in d:\E\AjaxTk-AjaxControlToolkit\Release\AjaxControlToolkit\ExtenderBase\ScriptObjectBuilder.cs:293 AjaxControlToolkit.ExtenderControlBase.OnLoad(EventArgs e) in d:\E\AjaxTk-AjaxControlToolkit\Release\AjaxControlToolkit\ExtenderBase\ExtenderControlBase.cs:306 System.Web.UI.Control.LoadRecursive()
+50    System.Web.UI.Control.LoadRecursive()
+141    System.Web.UI.Control.LoadRecursive()
+141    System.Web.UI.Control.LoadRecursive()
+141    System.Web.UI.Control.LoadRecursive()             
+141    System.Web.UI.Control.LoadRecursive()
+141    System.Web.UI.Control.LoadRecursive()
+141    System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627


Version Information: Microsoft .NET Framework Version:2.0.50727.3074; ASP.NET Version:2.0.50727.3074

我尝试在用户控件中放置一个占位符,并以编程方式将文本框和滑块扩展器添加到占位符,但我仍然得到错误。

下面是简单的代码:

<table cellpadding="0" cellspacing="0" style="width:100%">
    <tbody>
        <tr>
            <td></td>
            <td>
                <asp:Label ID="lblMaxValue" runat="server" Text="Maximum" CssClass="float_right" />
                <asp:Label ID="lblMinValue" runat="server" Text="Minimum" />
            </td>
        </tr>
        <tr>
            <td style="width:60%;">
                <asp:CheckBox ID="chkOn" runat="server" />
                <asp:Label ID="lblPrefix" runat="server" />:&nbsp;
                <asp:Label ID="lblSliderValue" runat="server" />&nbsp;
                <asp:Label ID="lblSuffix" runat="server" />
            </td>
            <td style="text-align:right;width:40%;">                

                    <asp:TextBox ID="txtSlider" runat="server" Text="50" style="display:none;" />
                    <ajaxToolkit:SliderExtender ID="seSlider" runat="server" 
                        BehaviorID="seSlider" 
                        TargetControlID="txtSlider" 
                        BoundControlID="lblSliderValue" 
                        Orientation="Horizontal" 
                        EnableHandleAnimation="true" 
                        Length="200" 
                        Minimum="0" 
                        Maximum="100" 
                        Steps="1" />

            </td>
        </tr>
    </tbody>
</table>

有什么问题吗?


当前回答

标签<%= %>不能作为runat="server"的标签。将<%= %>的代码移到runat="server"到另一个标记(body, head,…),或从容器中删除runat="server"。

其他回答

将java脚本代码保存在body标记中

<body> 
   <script type="text/javascript">
   </script>
</body>

我在用户控件中也有同样的问题。我的页面,托管控件有评论在头部标签,我删除了那些评论,一切工作之后。一些帖子还建议将脚本从头部移到正文中。

“<%#”数据绑定技术不会直接在<head>标签中的<link>标签内工作:

<head runat="server">

  <link rel="stylesheet" type="text/css" 
        href="css/style.css?v=<%# My.Constants.CSS_VERSION %>" />

</head>

上面的代码将计算为

<head>

  <link rel="stylesheet" type="text/css" 
        href="css/style.css?v=&lt;%# My.Constants.CSS_VERSION %>" />

</head>

相反,你应该做以下事情(注意里面的两个双引号):

<head runat="server">

  <link rel="stylesheet" type="text/css" 
        href="css/style.css?v=<%# "" + My.Constants.CSS_VERSION %>" />

</head>

你会得到你想要的结果:

<head>

  <link rel="stylesheet" type="text/css" href="css/style.css?v=1.5" />

</head>

首先,用<%#开始代码块,而不是<%=:

<head id="head1" runat="server">
  <title>My Page</title>
  <link href="css/common.css" rel="stylesheet" type="text/css" />
  <script type="text/javascript" src="<%# ResolveUrl("~/javascript/leesUtils.js") %>"></script>
</head>

这将更改来自响应的代码块。将代码块写入数据绑定表达式。 自从<%#…%>数据绑定表达式不是代码块,CLR不会抱怨。然后在母版页的代码中,添加以下内容:

protected void Page_Load(object sender, EventArgs e)
{
  Page.Header.DataBind();    
}

试着写你的java脚本代码以外的头标签,它肯定会工作。当我复制并粘贴我的Java脚本代码到页面底部时,它就解决了。在以前它放在HEAD标签,现在只是在关闭表单标签之前。

    </div>
        <script>
                    function validate() {
                        try {

                        var username = document.getElementById("<%=txtUserName.ClientID%>").value;
                        var password = document.getElementById("<%=txtPWD.ClientID%>").value;

                            if (username == "" && password == "")
                                alert("Enter Username and Passowrd");
                            else {
                                if (username == "")
                                    alert("Enter Username");
                                else if (password == "")
                                    alert("Enter Password");
                            }

                        }

                    catch (err) {
                    }
                }
                </script>
</form>