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RequiredFieldValidator.AddAttributesToRender-Methode

  • Artikel

Fügt dem angegebenen HtmlTextWriter-Objekt die HTML-Attribute und -Stile hinzu, die für das Steuerelement wiedergegeben werden sollen.

Namespace: System.Web.UI.WebControls
Assembly: System.Web (in system.web.dll)

Syntax

'Declaration
Protected Overrides Sub AddAttributesToRender ( _
    writer As HtmlTextWriter _
)
'Usage
Dim writer As HtmlTextWriter

Me.AddAttributesToRender(writer)

protected override void AddAttributesToRender (
    HtmlTextWriter writer
)

protected:
virtual void AddAttributesToRender (
    HtmlTextWriter^ writer
) override

protected void AddAttributesToRender (
    HtmlTextWriter writer
)

protected override function AddAttributesToRender (
    writer : HtmlTextWriter
)

Parameter

  • writer
    Ein HtmlTextWriter, der den Ausgabestream für die Wiedergabe des HTML-Inhalts auf dem Client darstellt.

Beispiel

Im folgenden Codebeispiel wird das Überschreiben der AddAttributesToRender-Methode in einem benutzerdefinierten Serversteuerelement veranschaulicht, sodass die RequiredFieldValidator-Fehlermeldung immer fett formatiert angezeigt wird.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page Language="VB" AutoEventWireup="True" %>
<HTML>
    <HEAD>
        <title>Custom RequiredFieldValidator - AddAttributesToRender - VB.NET Example</title>
        <script runat="server">
            Sub Button1_Click(sender As Object, e As EventArgs) 
            
                If Page.IsValid Then 
                
                    Label1.Text = "Required field is filled!"
                
                Else 
                
                    Label1.Text = "Required field is empty!"
                
                End If

            End Sub
        </script>
    </HEAD>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom RequiredFieldValidator - AddAttributesToRender - VB.NET Example</h3>

            <table border="0" cellpadding="4" cellspacing="0">
                <tr valign="top">
                    <td colspan="3">
                        <asp:Label ID="Label1" runat="server" 
                         Text="Fill in the required field below" />
                    </td>
                </tr>
                <tr>
                    <td align="right">Card Number:</td>
                    <td>
                        <asp:TextBox id="TextBox1" runat="server" />
                    </td>
                    <td>
                        <aspSample:CustomRequiredFieldValidatorAddAttributesToRender id="RequiredFieldValidator1" 
                         runat="server" ControlToValidate="TextBox1" Display="Static" ErrorMessage="Required" />
                    </td>
                </tr>
                <tr>
                    <td>&nbsp;</td>
                    <td>
                        <asp:Button id="Button1" runat="server" Text="Validate" 
                         OnClick="Button1_Click" />
                    </td>
                    <td>&nbsp;</td>
                </tr>
            </table>


        </form>
    </body>
</HTML>

...
Imports System.Web
Imports System.Security.Permissions

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

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

            ' Show the RequiredFieldValidator's 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

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page Language="C#" AutoEventWireup="True" %>
<HTML>
  <HEAD>
    <title>Custom RequiredFieldValidator - AddAttributesToRender - C# Example</title>
    <script runat="server">
      void Button1_Click(Object sender, EventArgs e) 
      {
        if (Page.IsValid) 
        {
          Label1.Text = "Required field is filled!";
        }
        else 
        {
          Label1.Text = "Required field is empty!";
        }
      }
    </script>
  </HEAD>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom RequiredFieldValidator - AddAttributesToRender - C# Example</h3>

      <table border="0" cellpadding="4" cellspacing="0">
        <tr valign="top">
          <td colspan="3">
            <asp:Label ID="Label1" runat="server" Text="Fill in the required field below" />
          </td>
        </tr>
        <tr>
          <td align="right">Card Number:</td>
          <td>
            <asp:TextBox id="TextBox1" runat="server" />
          </td>
          <td>
            <aspSample:CustomRequiredFieldValidatorAddAttributesToRender 
              id="RequiredFieldValidator1" 
              runat="server" 
              ControlToValidate="TextBox1" 
              Display="Static" 
              ErrorMessage="Required" />
          </td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td>
            <asp:Button id="Button1" runat="server" Text="Validate" OnClick="Button1_Click" />
          </td>
          <td>&nbsp;</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 CustomRequiredFieldValidatorAddAttributesToRender : System.Web.UI.WebControls.RequiredFieldValidator
  {
    protected override void AddAttributesToRender(System.Web.UI.HtmlTextWriter writer)
    {
      // Show the RequiredFieldValidator's error message as bold.
      writer.AddStyleAttribute(System.Web.UI.HtmlTextWriterStyle.FontWeight, "bold");
      
      // Call the Base's AddAttributesToRender method.
      base.AddAttributesToRender(writer);
    }
  }
}

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSL.Controls" Assembly="Samples.AspNet.JSL" %>
<%@ Page Language="VJ#" AutoEventWireup="True" %>
<HTML>
  <HEAD>
    <title>Custom RequiredFieldValidator - AddAttributesToRender - VJ# Example</title>
    <script runat="server">
        void Button1_Click(Object sender, EventArgs e) 
        {
            if (get_Page().get_IsValid()) {
                Label1.set_Text("Required field is filled!");
            }
            else {
                Label1.set_Text("Required field is empty!");
            }
        } //Button1_Click
    </script>
  </HEAD>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom RequiredFieldValidator - AddAttributesToRender - VJ# Example</h3>

      <table border="0" cellpadding="4" cellspacing="0">
        <tr valign="top">
          <td colspan="3">
            <asp:Label ID="Label1" runat="server" Text="Fill in the required field below" />
          </td>
        </tr>
        <tr>
          <td align="right">Card Number:</td>
          <td>
            <asp:TextBox id="TextBox1" runat="server" />
          </td>
          <td>
            <aspSample:CustomRequiredFieldValidatorAddAttributesToRender 
              id="RequiredFieldValidator1" 
              runat="server" 
              ControlToValidate="TextBox1" 
              Display="Static" 
              ErrorMessage="Required" />
          </td>
        </tr>
        <tr>
          <td>&nbsp;</td>
          <td>
            <asp:Button id="Button1" runat="server" Text="Validate" OnClick="Button1_Click" />
          </td>
          <td>&nbsp;</td>
        </tr>
      </table>


    </form>
  </body>
</HTML>

...
package Samples.AspNet.JSL.Controls; 

public class CustomRequiredFieldValidatorAddAttributesToRender
    extends System.Web.UI.WebControls.RequiredFieldValidator
{
    protected void AddAttributesToRender(System.Web.UI.HtmlTextWriter writer)
    {
        // Show the RequiredFieldValidator's error message as bold.
        writer.AddStyleAttribute(System.Web.UI.HtmlTextWriterStyle.FontWeight, 
            "bold");
        // Call the Base's AddAttributesToRender method.
        super.AddAttributesToRender(writer);
    } //AddAttributesToRender
} //CustomRequiredFieldValidatorAddAttributesToRender

Plattformen

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.

Versionsinformationen

.NET Framework

Unterstützt in: 2.0, 1.1, 1.0

Siehe auch

Referenz

RequiredFieldValidator-Klasse
RequiredFieldValidator-Member
System.Web.UI.WebControls-Namespace