ValidationSummary.OnPreRender(EventArgs) 方法

定义

引发 PreRender 事件。Raises the PreRender event.

protected:
 override void OnPreRender(EventArgs ^ e);
protected public:
 override void OnPreRender(EventArgs ^ e);
protected override void OnPreRender (EventArgs e);
protected internal override void OnPreRender (EventArgs e);
override this.OnPreRender : EventArgs -> unit
Protected Overrides Sub OnPreRender (e As EventArgs)
Protected Friend Overrides Sub OnPreRender (e As EventArgs)

参数

e
EventArgs

包含事件数据的 EventArgsAn EventArgs that contains the event data.

示例

下面的代码示例演示如何重写 OnPreRender 方法,以便它始终在自定义服务器控件中将错误消息显示为粗体 ValidationSummaryThe following code example demonstrates how to override the OnPreRender method so that it always displays error messages as bold in a custom ValidationSummary server control.

重要

此示例具有一个接受用户输入的文本框,这是一个潜在的安全威胁。This example has a text box that accepts user input, which is a potential security threat. 默认情况下,ASP.NET 网页验证用户输入是否不包含脚本或 HTML 元素。By default, ASP.NET Web pages validate that user input does not include script or HTML elements. 有关详细信息,请参阅脚本侵入概述For more information, see Script Exploits Overview.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page Language="C#" AutoEventWireup="True" %>
<!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>
        <title>Custom ValidationSummary - AddAttributesToRender - C# Example</title>
    </head>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom ValidationSummary - AddAttributesToRender - C# Example</h3>

      <table id="Table1" cellpadding="4" cellspacing="0">
        <tr>
          <td>
            <table id="Table2" cellpadding="4" cellspacing="0"
             style="background-color:#eeeeee;">
              <tr>
                <td colspan="3"><b>Credit Card Information</b> </td>
              </tr>
              <tr>
                <td align="right">Card Type: </td>
                <td>
                  <asp:RadioButtonList id="RadioButtonList1" runat="server" RepeatLayout="Flow">
                      <asp:ListItem>MasterCard</asp:ListItem>
                      <asp:ListItem>Visa</asp:ListItem>
                  </asp:RadioButtonList>
                </td>
                <td align="center" rowspan="1">
                  <asp:RequiredFieldValidator 
                    id="RequiredFieldValidator1" 
                    runat="server" 
                    ErrorMessage="Card Type" 
                    Width="100%" 
                    Display="Static" 
                    ControlToValidate="RadioButtonList1">*
                  </asp:RequiredFieldValidator>
                </td>
              </tr>
              <tr>
                <td align="right">Card Number: </td>
                <td><asp:TextBox id="TextBox1" runat="server"></asp:TextBox></td>
                <td>
                  <asp:RequiredFieldValidator 
                    id="RequiredFieldValidator2" 
                    runat="server" 
                    ErrorMessage="Card Number" 
                    Width="100%" 
                    Display="Static" 
                    ControlToValidate="TextBox1">*
                  </asp:RequiredFieldValidator>
                </td>
              </tr>
              <tr>
                <td></td>
                <td><asp:Button id="Button1" runat="server" text="Validate"></asp:Button></td>
                <td></td>
              </tr>
            </table>
          </td>
        </tr>
        <tr>
          <td valign="top">
            <aspSample:CustomValidationSummaryAddAttributesToRender
              id="ValidationSummary1" 
              runat="server" 
              DisplayMode="BulletList" 
              HeaderText="You must enter a value in the following fields:" />
          </td>
        </tr>
      </table>

        </form>
    </body>
</html>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page Language="VB" AutoEventWireup="True" %>
<!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>
        <title>Custom ValidationSummary - AddAttributesToRender - VB.NET Example</title>
    </head>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom ValidationSummary - AddAttributesToRender - VB.NET Example</h3>


                <table id="Table1" cellpadding="4" cellspacing="0">
                    <tr>
                        <td>
                            <table id="Table2" cellpadding="4" cellspacing="0" style="background-color:#eeeeee">
                                <tr>
                                    <td colspan="3"><b>Credit Card Information</b> </td>
                                </tr>
                                <tr>
                                    <td align="right">Card Type: </td>
                                    <td><asp:RadioButtonList id="RadioButtonList1" runat="server" RepeatLayout="Flow">
                                            <asp:ListItem>MasterCard</asp:ListItem>
                                            <asp:ListItem>Visa</asp:ListItem>
                                        </asp:RadioButtonList>
                                    </td>
                                    <td align="center" rowspan="1">
                                        <asp:RequiredFieldValidator id="RequiredFieldValidator1" 
                                         runat="server" ErrorMessage="Card Type. " Width="100%" 
                                         Display="Static" ControlToValidate="RadioButtonList1">*</asp:RequiredFieldValidator>
                                    </td>
                                </tr>
                                <tr>
                                    <td align="right">Card Number: </td>
                                    <td><asp:TextBox id="TextBox1" runat="server"></asp:TextBox></td>
                                    <td>
                                        <asp:RequiredFieldValidator id="RequiredFieldValidator2" 
                                         runat="server" ErrorMessage="Card Number. " Width="100%" 
                                         Display="Static" ControlToValidate="TextBox1">*</asp:RequiredFieldValidator>
                                    </td>
                                </tr>
                                <tr>
                                    <td></td>
                                    <td><asp:Button id="Button1" runat="server" text="Validate"></asp:Button></td>
                                    <td></td>
                                </tr>
                            </table>
                        </td>
                        <td valign="top">
                            <table id="Table3" cellpadding="4" cellspacing="0" >
                                <tr>
                                    <td><aspSample:CustomValidationSummaryAddAttributesToRender
                                        id="ValidationSummary1" runat="server" DisplayMode="BulletList"
                                        HeaderText="You must enter a value in the following fields:" />
                                    </td>
                                </tr>
                            </table>
                        </td>
                     </tr>
                </table>

        </form>
    </body>
</html>
using System.Web;
using System.Security.Permissions;

namespace Samples.AspNet.CS.Controls
{
  [AspNetHostingPermission(SecurityAction.Demand, Level=AspNetHostingPermissionLevel.Minimal)]
  public sealed class CustomValidationSummaryAddAttributesToRender : System.Web.UI.WebControls.ValidationSummary
  {
    protected override void AddAttributesToRender(System.Web.UI.HtmlTextWriter writer)
    {
      // Show the error message as bold.
      writer.AddStyleAttribute(System.Web.UI.HtmlTextWriterStyle.FontWeight, "bold");
      
      // Call the Base's AddAttributesToRender method.
      base.AddAttributesToRender(writer);
    }
  }
}
Imports System.Web
Imports System.Security.Permissions

Namespace Samples.AspNet.VB.Controls
    <AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
    Public NotInheritable Class CustomValidationSummaryAddAttributesToRender
        Inherits System.Web.UI.WebControls.ValidationSummary

        Protected Overrides Sub AddAttributesToRender(ByVal writer As System.Web.UI.HtmlTextWriter)

            ' Show the error message as bold.
            writer.AddStyleAttribute(System.Web.UI.HtmlTextWriterStyle.FontWeight, "bold")

            ' Call the Base's AddAttributesToRender method.
            MyBase.AddAttributesToRender(writer)
        End Sub
    End Class
End Namespace

适用于