只能在执行 Render() 的过程中调用 RegisterForEventValidation

https://www.cnblogs.com/gsk99/archive/2011/10/17/2215364.html

当在导出Execl或Word的时候，会发生只能在执行 Render() 的过程中调用 RegisterForEventValidation的错误提示。
下面的2中方法是在网上找到的，没有应用：
1.修改web.config(不推荐)

<pages enableEventValidation ="false" ></pages>

 

2.直接在导出Execl的页面修改

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="ExportWordByIO.aspx.cs" Inherits="_Default" EnableEventValidation = "false"  %>

 

我自己应用的处理方法：

还有一种情况，是因为导出到excel文件的控件中包含内部控件（比如linkbutton，button，超链接等），需要将这些内部控件转换为文本才可以。
在导出数据之前，使用ClearControls()方法清除内部控件。

 

    /// <summary>
    /// 导出Excel功能
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void Btn_Excel_Click(object sender, EventArgs e)
    {
        //导出全部数据，取消分页
        GridView_BatchQuality.AllowPaging = false;
        GridView_BatchQuality.ShowFooter = false;

        BindGridView();

        Response.Clear();
        Response.Buffer = true;
        Response.Charset = "utf-8";
        Response.AppendHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode("导出" + System.DateTime.Now.Date.ToString("yyyyMMdd")) + ".xls");
        Response.ContentEncoding = System.Text.Encoding.GetEncoding("utf-8");//设置输出流为简体中文

        Response.ContentType = "application/ms-excel";//设置输出文件类型为excel文件。 
        this.EnableViewState = false;
        System.Globalization.CultureInfo myCItrad = new System.Globalization.CultureInfo("ZH-CN", true);
        System.IO.StringWriter oStringWriter = new System.IO.StringWriter(myCItrad);
        System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);

        ClearControls(GridView_BatchQuality);
        this.GridView_BatchQuality.RenderControl(oHtmlTextWriter);
        Response.Write(oStringWriter.ToString());
        Response.End();

        //还原分页显示
        GridView_BatchQuality.AllowPaging = true;
        GridView_BatchQuality.ShowFooter = true;
        BindGridView();
    }

    /// <summary>
    /// GridView如果需要实现导出Excel功能，则该函数需要重载
    /// </summary>
    /// <param name="control"></param>
    public override void VerifyRenderingInServerForm(Control control)
    {
        // Confirms that an HtmlForm control is rendered for
    }

    /// <summary>
    /// 清除控件中的所有控件，以便导出Excel
    /// </summary>
    /// <param name="control"></param>
    private void ClearControls(Control control)
    {
        for (int i = control.Controls.Count - 1; i >= 0; i--)
        {
            ClearControls(control.Controls[i]);
        }

        if (!(control is TableCell))
        {
            if (control.GetType().GetProperty("SelectedItem") != null)
            {
                LiteralControl literal = new LiteralControl();
                control.Parent.Controls.Add(literal);
                try
                {
                    literal.Text = (string)control.GetType().GetProperty("SelectedItem").GetValue(control, null);
                }
                catch
                {
                }
                control.Parent.Controls.Remove(control);
            }
            else if (control.GetType().GetProperty("Text") != null)
            {
                LiteralControl literal = new LiteralControl();
                control.Parent.Controls.Add(literal);
                literal.Text = (string)control.GetType().GetProperty("Text").GetValue(control, null);
                control.Parent.Controls.Remove(control);
            }
        }
        return;
    }