c# - 在 Asp.Net 中使用复选框发送电子邮件

Question

我尝试在 asp.net 中发送电子邮件。当管理员选择复选框时，他/她能够将邮件发送到相应的电子邮件 ID，并且电子邮件也存储在用户表的数据库中。但是当我构建代码时，它会显示给我错误

代码是

protected void chkSelectAll_CheckedChanged(object sender, EventArgs e)
{
    CheckBox chkAll =
           (CheckBox)Repeateremail.HeaderRow.FindControl("chkSelectAll");
    if (chkAll.Checked == true)
    {
        foreach (GridViewRow gvRow in Repeateremail.Items)
        {
            CheckBox chkSel =
                     (CheckBox)gvRow.FindControl("chkSelect");
            chkSel.Checked = true;
        }
    }
    else
    {
        foreach (GridViewRow gvRow in Repeateremail.Items)
        {
            CheckBox chkSel = (CheckBox)gvRow.FindControl("chkSelect");
            chkSel.Checked = false;
        }
    }
}

在这一行

CheckBox chkAll =
           (CheckBox)Repeateremail.HeaderRow.FindControl("chkSelectAll");

它显示标题中的错误错误

'System.Web.UI.WebControls.Repeater' does not contain a definition for 'HeaderRow' and no extension method 'HeaderRow' accepting a first argument of type 'System.Web.UI.WebControls.Repeater' could be found (are you missing a using directive or an assembly
reference?)

在 html 中，我在标题模板中使用这样的地方

<td>
    Check
    <asp:CheckBox ID="chkSelectAll" runat="server"
                  AutoPostBack="true"
                  OnCheckedChanged="chkSelectAll_CheckedChanged"/>
    Send Mail To All ?                     
</td>

在项目模板中

<td>
    <asp:CheckBox ID="chkSelect" runat="server"/>
</td>

Answer 1

您不需要使用 FindControl() 方法，因为您正在处理要检查其属性值的控件的点击事件，请试试这个:

protected void chkSelectAll_CheckedChanged(object sender, EventArgs e)
{
    // Cast the sender to a CheckBox type
    CheckBox chkAll = sender as CheckBox;

    // The as operator will return null if the cast is not successful,
    // so check for null before we try to use it
    if(chkAll != null)
    {
        if (chkAll.Checked == true)
        {
            foreach (GridViewRow gvRow in Repeateremail.Items)
            {
                CheckBox chkSel =
                 (CheckBox)gvRow.FindControl("chkSelect");
                chkSel.Checked = true;
            }
        }
        else
        {
            foreach (GridViewRow gvRow in Repeateremail.Items)
            {
                CheckBox chkSel = (CheckBox)gvRow.FindControl("chkSelect");
                chkSel.Checked = false;
            }
        }
    }
}