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CustomValidator.AddAttributesToRender(HtmlTextWriter) Metodo

  • Riferimento

Definizione

Spazio dei nomi:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Consente di aggiungere le proprietà del controllo CustomValidator al flusso di output per il rendering sul client.

protected:
 override void AddAttributesToRender(System::Web::UI::HtmlTextWriter ^ writer);
protected override void AddAttributesToRender (System.Web.UI.HtmlTextWriter writer);
override this.AddAttributesToRender : System.Web.UI.HtmlTextWriter -> unit
Protected Overrides Sub AddAttributesToRender (writer As HtmlTextWriter)

Parametri

writer
HtmlTextWriter

Oggetto HtmlTextWriter che contiene il flusso di output per il rendering nel client.

Esempio

Nell'esempio di codice seguente viene illustrato come eseguire l'override del AddAttributesToRender metodo in un controllo server personalizzato in modo che il CustomValidator messaggio di errore venga sempre visualizzato in grassetto.

Importante

L'esempio include una casella di testo che accetta l'input dell'utente e rappresenta quindi una potenziale minaccia alla sicurezza. Per impostazione predefinita, le pagine Web ASP.NET verificano che l'input dell'utente non includa script o elementi HTML. Per altre informazioni, vedere Cenni preliminari sugli attacchi tramite script.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet" 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 CustomValidator - AddAttributesToRender - C# Example</title>
    <script runat="server">
    void CustomValidator1_ServerValidate(Object source, ServerValidateEventArgs args) 
    {
      try 
      {
        // Test whether the value entered into the text box is even.
        int i = int.Parse(args.Value);
        args.IsValid = ((i%2) == 0);
      }
      catch(Exception ex)
      {
        args.IsValid = false;
      }
    }
    </script>
  </head>
<body>
  <form id="Form1" method="post" runat="server">
    <h3>Custom CustomValidator - AddAttributesToRender - C# Example</h3>
    
    <asp:Label id="Label1" runat="server" 
    Text="Enter an even number:" AssociatedControlID="TextBox1"/><br />
    
    <asp:TextBox id="TextBox1" runat="server" /> 
    
    <aspSample:CustomCustomValidatorAddAttributesToRender 
      id="Customvalidator1" 
      runat="server" 
      ControlToValidate="TextBox1" 
      Display="Static" 
      ErrorMessage="Not an even number!" 
      OnServerValidate="CustomValidator1_ServerValidate" /><br /><br />
    
    <asp:Button id="Button1" runat="server" Text="Validate" />
    
  </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 CustomValidator - AddAttributesToRender - VB.NET Example</title>
    <script runat="server">
      Sub CustomValidator1_ServerValidate(source As Object, args As ServerValidateEventArgs)
        args.IsValid = False
        Try
          ' Test whether the value entered into the text box is even or not.
          Dim i As Integer = Integer.Parse(args.Value)
          If (i Mod 2) = 0 Then
            args.IsValid = True
          End If
        Catch
        End Try
      End Sub
    </script>
  </head>
<body>
  <form id="Form1" method="post" runat="server">
    <h3>Custom CustomValidator - AddAttributesToRender - VB.NET Example</h3>
    <asp:Label id="Label1" runat="server" Text="Enter an even number:" AssociatedControlID="TextBox1" /><br />
    <asp:TextBox id="TextBox1" runat="server" /> 
    <aspSample:CustomCustomValidatorAddAttributesToRender id="Customvalidator1" runat="server" ControlToValidate="TextBox1" Display="Static" ErrorMessage="Not an even number!" OnServerValidate="CustomValidator1_ServerValidate" /><br /><br />
    <asp:Button id="Button1" runat="server" Text="Validate" />
  </form>
</body>
</html>

using System.Web;
using System.Security.Permissions;

namespace Samples.AspNet
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomCustomValidatorAddAttributesToRender : System.Web.UI.WebControls.CustomValidator
    {
        protected override void AddAttributesToRender(System.Web.UI.HtmlTextWriter writer)
        {
        // Show the CompareValidator's 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 CustomCustomValidatorAddAttributesToRender
        Inherits System.Web.UI.WebControls.CustomValidator

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

            ' Show the CompareValidator'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

Si applica a