ASP.NET AJAX Advance Tips & Tricks (10) 解决使用AJAX Extender时的页面导出(Word/Excel)问题(Extender control 'XXX' is not a registered extender control)

前言：

有客户问到这么个问题：我们可以使用Response容易地将ASP.NET页面导出为Excel或Word。然而，如果有AJAX Control Toolkit的Extender在页面上的话，则会发生错误(Extender control 'XXX' is not a registered extender control)。我搜索了一下，ASP.NET forum里有很多这样的问题未能解决，故写了这个解决方案，与大家分享。

问题重现：

首先，使用Response将ASP.NET页面导出为Excel或Word，代码比较简单，如下所示：

    public void ExportControl(System.Web.UI.Control source, DocumentType type,string name)
    {
        if (type == DocumentType.Excel)
        {
            //Excel
            Response.AppendHeader("Content-Disposition", "attachment;filename="+name+".xls");
            Response.ContentType = "application/ms-excel";
        }
        else if (type == DocumentType.Word)
        {
            //Word
            Response.AppendHeader("Content-Disposition", "attachment;filename=" + name + ".doc");
            Response.ContentType = "application/ms-word";
        }
        Response.Charset = "UTF-8";
        Response.ContentEncoding = System.Text.Encoding.UTF8;

        source.Page.EnableViewState = false;

        System.IO.StringWriter writer = new System.IO.StringWriter();
        System.Web.UI.HtmlTextWriter htmlWriter = new System.Web.UI.HtmlTextWriter(writer);
        source.RenderControl(htmlWriter);

        Response.Write(writer.ToString());
        Response.End();
    }

    public enum DocumentType
    {
        Word,
        Excel
    }

然而，在下面的例子中，我们将会得到一个令人厌烦的错误：

<%@ Page Language="C#" EnableEventValidation = "false" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

protected void Button2_Click(object sender, EventArgs e)

{

ExportControl(this, DocumentType.Word, "ExportWord");

}

public override void VerifyRenderingInServerForm(Control control)

{

}

public void ExportControl(System.Web.UI.Control source, DocumentType type,string name)

{

if (type == DocumentType.Excel)

{

//Excel

Response.AppendHeader("Content-Disposition", "attachment;filename="+name+".xls");

Response.ContentType = "application/ms-excel";

}

else if (type == DocumentType.Word)

{

//Word

Response.AppendHeader("Content-Disposition", "attachment;filename=" + name + ".doc");

Response.ContentType = "application/ms-word";

}

Response.Charset = "UTF-8";

Response.ContentEncoding = System.Text.Encoding.UTF8;

source.Page.EnableViewState = false;

System.IO.StringWriter writer = new System.IO.StringWriter();

System.Web.UI.HtmlTextWriter htmlWriter = new System.Web.UI.HtmlTextWriter(writer);

source.RenderControl(htmlWriter);

Response.Write(writer.ToString());

Response.End();

}

public enum DocumentType

{

Word,

Excel

}

</script>

</head>

<body>

<div>

<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true" />

</div>

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

<ajaxToolkit:CalendarExtender ID="TextBox1_CalendarExtender" runat="server" Enabled="True"

TargetControlID="TextBox1">

</ajaxToolkit:CalendarExtender>

<br />

<asp:Panel ID="Panel1" runat="server" Height="100px" Width="194px" BackColor="Chocolate">

</asp:Panel>

<ajaxToolkit:RoundedCornersExtender ID="Panel1_RoundedCornersExtender" runat="server"

Enabled="True" TargetControlID="Panel1">

</ajaxToolkit:RoundedCornersExtender>

<br />

</p>

<asp:Button ID="Button2" runat="server" OnClick="Button2_Click" Text="Download" />

</form>

</body>

</html>

错误信息如下：

Server Error in '/AjaxControlToolkitWebSite2' Application.
--------------------------------------------------------------------------------

Extender control 'TextBox1_CalendarExtender' is not a registered extender control. Extender controls must be registered using RegisterExtenderControl() before calling RegisterScriptDescriptors().
Parameter name: extenderControl

分析：

显然，问题是出现在AJAX Extender上，如果把页面上的AJAX Extender全部删除，则工作正常。

有此，该问题的解决思路为“在导出之前移除页面上所有的Extender”

解决方案：

使用递归方式，在导出之前移除所有AJAX Extenders:

    private void DisableAJAXExtenders(Control parent)
    {
        for (int i = 0; i < parent.Controls.Count; i++)
        {
            if (parent.Controls[i].GetType().ToString().IndexOf("Extender") != -1 && parent.Controls[i].ID != null)
            {
                parent.Controls.RemoveAt(i);
                parent.Controls[i].Dispose();
            }
            if (parent.Controls[i].Controls.Count > 0)
            {
                DisableAJAXExtenders(parent.Controls[i]);
            }
        }
    }

如下例所示，页面可成功导出为Word/Excel:

<%@ Page Language="C#" EnableEventValidation = "false"  %>

<!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 Button2_Click(object sender, EventArgs e)
    {
        //DisableAJAXExtenders(this);
        ExportControl(this, DocumentType.Word, "ExportWord");
    }

    private void DisableAJAXExtenders(Control parent)
    {
        for (int i = 0; i < parent.Controls.Count; i++)
        {
            if (parent.Controls[i].GetType().ToString().IndexOf("Extender") != -1 && parent.Controls[i].ID != null)
            {
                parent.Controls.RemoveAt(i);
                parent.Controls[i].Dispose();
            }
            if (parent.Controls[i].Controls.Count > 0)
            {
                DisableAJAXExtenders(parent.Controls[i]);
            }
        }
    }

    public override void VerifyRenderingInServerForm(Control control)
    {

    }

    public void ExportControl(System.Web.UI.Control source, DocumentType type,string name)
    {
        if (type == DocumentType.Excel)
        {
            //Excel
            Response.AppendHeader("Content-Disposition", "attachment;filename="+name+".xls");
            Response.ContentType = "application/ms-excel";
        }
        else if (type == DocumentType.Word)
        {
            //Word
            Response.AppendHeader("Content-Disposition", "attachment;filename=" + name + ".doc");
            Response.ContentType = "application/ms-word";
        }
        Response.Charset = "UTF-8";
        Response.ContentEncoding = System.Text.Encoding.UTF8;

        source.Page.EnableViewState = false;

        System.IO.StringWriter writer = new System.IO.StringWriter();
        System.Web.UI.HtmlTextWriter htmlWriter = new System.Web.UI.HtmlTextWriter(writer);
        source.RenderControl(htmlWriter);

        Response.Write(writer.ToString());
        Response.End();
    }

    public enum DocumentType
    {
        Word,
        Excel
    }

</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true" />
    </div>
    <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
    <ajaxToolkit:CalendarExtender ID="TextBox1_CalendarExtender" runat="server" Enabled="True"
        TargetControlID="TextBox1">
    </ajaxToolkit:CalendarExtender>
    <br />
    <br />
    <br />
    <asp:Panel ID="Panel1" runat="server" Height="100px" Width="194px" BackColor="Chocolate">
    </asp:Panel>
    <ajaxToolkit:RoundedCornersExtender ID="Panel1_RoundedCornersExtender" runat="server"
        Enabled="True" TargetControlID="Panel1">
    </ajaxToolkit:RoundedCornersExtender>
    <br />
    <br />
    <asp:Button ID="Button2" runat="server" OnClick="Button2_Click" Text="Download" />
    </form>
</body>
</html>

PS：

一般情况下，如果想要移除页面上的所有AJAX Extender，也可以采用JavaScript的方式：

Code

ASP.NET AJAX Advance Tips & Tricks (10) 解决使用AJAX Extender时的页面导出(Word/Excel)问题(Extender control 'XXX' is not a registered extender control)

前言：

问题重现：

分析：

PS：

相关Case：

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