HtmlInputHidden.OnPreRender(EventArgs) Metodo

  • Riferimento

Definizione

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

Genera l'evento PreRender.

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)

Parametri

e
EventArgs

Oggetto EventArgs che contiene i dati dell'evento.

Esempio

Nell'esempio di codice seguente viene illustrato come eseguire l'override del OnPreRender metodo in modo che applichi la codifica HTML al valore di input in un controllo server personalizzato HtmlInputHidden .

<%@ 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 HtmlInputHidden - OnPreRender - C# Example</title>
    <script runat="server">
      void Page_Load(Object sender, EventArgs e) 
      {
        HtmlInputHidden1.Value = "<Hello Html Input Hidden World.>";
      }
    </script>
    </head>
    <body onload="alert('View the source to see the HTML Hidden Input value.')">
        <form id="Form1" method="post" runat="server">
            <h3>Custom HtmlInputHidden - OnPreRender - C# Example</h3>
        
          <aspSample:CustomHtmlInputHiddenOnPreRender 
            id="HtmlInputHidden1" 
            name="HtmlInputHidden1"
            runat="server" 
            type="hidden">
            
        </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 HtmlInputHidden - OnPreRender - Visual Basic Example</title>
    
    <script runat="server">
      Sub Page_Load(sender As Object, e As EventArgs)
        HtmlInputHidden1.Value = "<Hello HtmlInputHidden World>"
      End Sub
    </script>
    </head>
    <body onload="alert('View the source to see the HTML Hidden Input value.')">
        <form id="Form1" method="post" runat="server">
            <h3>Custom HtmlInputHidden - OnPreRender - Visual Basic Example</h3>
        
          <aspSample:CustomHtmlInputHiddenOnPreRender 
            id="HtmlInputHidden1" 
            runat="server" 
            type="hidden">
            
        </form>
    </body>
</html>

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

namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomHtmlInputHiddenOnPreRender : System.Web.UI.HtmlControls.HtmlInputHidden
    {
        protected override void OnPreRender(System.EventArgs e)
        {
            // Call the base class's OnPreRender method.
            base.OnPreRender(e);
            
            // Encode the Hidden Input value as HTML.
            this.Value = System.Web.HttpContext.Current.Server.HtmlEncode(this.Value);
        }
    }
}

<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
Public NotInheritable Class CustomHtmlInputHiddenOnPreRender
    Inherits System.Web.UI.HtmlControls.HtmlInputHidden

    Protected Overrides Sub OnPreRender(ByVal e As System.EventArgs)

        ' Call the base class's OnPreRender method.
        MyBase.OnPreRender(e)

        ' Encode the Hidden Input value as HTML.
        Me.Value = System.Web.HttpContext.Current.Server.HtmlEncode(Me.Value)
    End Sub
End Class

Commenti

Il OnPreRender metodo viene chiamato subito prima del rendering del HtmlInputHidden controllo. Il OnPreRender metodo viene usato principalmente dagli sviluppatori di controlli che estendono la funzionalità del HtmlInputHidden controllo.

Si applica a

Vedi anche