HtmlInputText.OnPreRender(EventArgs) Method

Reference

Definition

Namespace:: System.Web.UI.HtmlControls

Assembly:: System.Web.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

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)

Parameters

e: EventArgs

An EventArgs that contains the event data.

Examples

The following code example demonstrates how to override the OnPreRender method so that it sets the MaxLength property to 30 characters in a custom HtmlInputText server control.

<%@ 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">
<script runat="server">

  void Page_Load(Object sender, EventArgs e) 
  {
    if (!Page.IsPostBack)
    {
      HtmlInputText1.Value = "Hello HtmlInputText World.";
    }
  }

  void HtmlInputText1_ServerChange(object sender, System.EventArgs e)
  {

    // Diplay the value of the selected HtmlInputText control.
    System.Web.UI.HtmlControls.HtmlInputText htmlInputText1 = (System.Web.UI.HtmlControls.HtmlInputText) sender;
    Div1.InnerHtml = "Change the preceding text to:<br />" + htmlInputText1.Value;

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>Custom HtmlInputText OnPreRender Example</title>
  </head>

  <body>
    
    <form id="Form1" method="post" runat="server">

      <h3>Custom HtmlInputText OnPreRender Example</h3>

      <p>Make a change to the text, and then press the ENTER.<br />

      <aspSample:CustomHtmlInputTextOnPreRender 
        id="HtmlInputText1" 
        name="HtmlInputText1" 
        runat="server" 
        type="text"
        size="45"
        style="WIDTH: 305px; HEIGHT: 22px" 
        onserverchange="HtmlInputText1_ServerChange">

      </p>
      <br />
      <div 
        id="Div1" 
        runat="server" 
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px" />
          
    </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">
<script runat="server">

  Sub Page_Load(sender As Object, e As EventArgs)

    If Not Page.IsPostBack Then

      HtmlInputText1.Value = "Hello HtmlInputText World."

    End If

  End Sub

  Sub HtmlInputText1_ServerChange(sender As Object, e As System.EventArgs)

    Dim htmlInputText1 As System.Web.UI.HtmlControls.HtmlInputText = CType(sender, System.Web.UI.HtmlControls.HtmlInputText)
    Div1.InnerHtml = "Change the preceding text to:<br />" & htmlInputText1.Value

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>Custom HtmlInputText OnPreRender Example</title>
  </head>

  <body>
    <form id="Form1" method="post" runat="server">

      <h3>Custom HtmlInputText OnPreRender Example</h3>

      <p>Make a change to the text, and then press the ENTER.<br />

      <aspSample:CustomHtmlInputTextOnPreRender 
        id="HtmlInputText1" 
        name="HtmlInputText1" 
        runat="server" 
        type="text"
        size="45"
        style="WIDTH: 305px; HEIGHT: 22px" 
        onserverchange="HtmlInputText1_ServerChange">

      </p>
      <br />
      <div 
        id="Div1" 
        runat="server" 
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px" />
          
    </form>
  </body>
</html>

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

namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomHtmlInputTextOnPreRender : System.Web.UI.HtmlControls.HtmlInputText
    {
        protected override void OnPreRender(System.EventArgs e)
        {
            // Call the base class's OnPreRender method.
            base.OnPreRender(e);

            // Set the HtmlInputText object's MaxLength property to 30 characters.
            this.MaxLength = 30;
        }
    }
}

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

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

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

        ' Set the HtmlInputText object's MaxLength property to 30 characters.
        Me.MaxLength = 30
    End Sub
End Class

Remarks

The OnPreRender method is called just prior to rendering the HtmlInputText control. The OnPreRender method is used primarily by control developers extending the functionality of the HtmlInputText control.

Applies to

Share via