HtmlSelect.ClearSelection Método

Definición

Borra la selección de lista del control HtmlSelect y establece la propiedad Selected de todos los elementos en false.

protected:
 virtual void ClearSelection();
protected virtual void ClearSelection ();
abstract member ClearSelection : unit -> unit
override this.ClearSelection : unit -> unit
Protected Overridable Sub ClearSelection ()

Ejemplos

En el ejemplo de código siguiente se muestra cómo invalidar el ClearSelection método en un control de servidor personalizado para que siempre borre todos los elementos seleccionados de una HtmlSelect colección.

<%@ 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 HtmlSelect - ClearSelection - C# Example</title>
        <script runat="server">
      void HtmlInputButton1_ServerClick(Object sender, EventArgs e) 
      {
        if (HtmlSelect1.SelectedIndex >= 0)
        {
          if (HtmlSelect1.Multiple == true)
          {
            Div1.InnerHtml = "You selected:";
            for (int i=0; i<=HtmlSelect1.Items.Count - 1; i++)
            {
              if (HtmlSelect1.Items[i].Selected == true)
              {
                Div1.InnerHtml += "<br />    " + HtmlSelect1.Items[i].Value; 
              }     
            }
          }
          else
          {
            Div1.InnerHtml = "You selected " + HtmlSelect1.Value;
          }
        }
        else
        {
          Div1.InnerHtml = "You did not select an item.";
        }
      }
        </script>
    </head>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom HtmlSelect - ClearSelection - C# Example</h3>
            
            <p>
      <aspSample:CustomHtmlSelectClearSelection 
        id="HtmlSelect1" multiple
        name="HtmlSelect1" 
        runat="server">
        <option value="Option1">Option1</option>
        <option value="Option2">Option2</option>
        <option value="Option3">Option3</option>
        <option value="Option4">Option4</option>
      </aspSample:CustomHtmlSelectClearSelection>
      </p>
      
      <p>
      <input 
        id="HtmlInputButton1" 
        runat="server" 
        type="button" 
        onserverclick="HtmlInputButton1_ServerClick"
        value="Select" 
        name="HtmlInputButton1" />  
      </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">
<html xmlns="http://www.w3.org/1999/xhtml" >
    <head>
        <title>Custom HtmlSelect - ClearSelection - VB.NET Example</title>
        <script runat="server">
      Sub HtmlInputButton1_ServerClick(sender As Object, e As EventArgs)
        If HtmlSelect1.SelectedIndex >= 0 Then
            If HtmlSelect1.Multiple = True Then
              Div1.InnerHtml = "You selected:"
              Dim i As Integer
              For i = 0 To HtmlSelect1.Items.Count - 1
                  If HtmlSelect1.Items(i).Selected = True Then
                    Div1.InnerHtml += "<br />    " & HtmlSelect1.Items(i).Value
                  End If
              Next i
            Else
              Div1.InnerHtml = "You selected " & HtmlSelect1.Value
            End If
        Else
            Div1.InnerHtml = "You did not select an item."
        End If
      End Sub
        </script>
    </head>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom HtmlSelect - ClearSelection - VB.NET Example</h3>
            
            <p>
      <aspSample:CustomHtmlSelectClearSelection 
        id="HtmlSelect1" multiple
        name="HtmlSelect1" 
        runat="server">
        <option value="Option1">Option1</option>
        <option value="Option2">Option2</option>
        <option value="Option3">Option3</option>
        <option value="Option4">Option4</option>
      </aspSample:CustomHtmlSelectClearSelection>
      </p>
      
      <p>
      <input 
        id="HtmlInputButton1" 
        runat="server" 
        type="button" 
        onserverclick="HtmlInputButton1_ServerClick"
        value="Select" 
        name="HtmlInputButton1" />  
      </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 CustomHtmlSelectClearSelection : System.Web.UI.HtmlControls.HtmlSelect
    {
        protected override void ClearSelection()
        {
            // For each item in the Items collection, 
            // set the Selected property to false.
            for (int i=0; i < Items.Count; i++)
            Items[i].Selected = false;
        }
    }
}
<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
Public NotInheritable Class CustomHtmlSelectClearSelection
    Inherits System.Web.UI.HtmlControls.HtmlSelect

    Protected Overrides Sub ClearSelection()

        ' For each item in the Items collection, 
        ' set the Selected property to false.
        Dim i As Integer
        For i = 0 To Items.Count - 1
            Items(i).Selected = False
        Next i
    End Sub
End Class

Comentarios

El ClearSelection método recorre en iteración la ListItemCollection colección representada por la HtmlSelect propiedad del Items control y establece la Selected propiedad de cada ListItem objeto en false.

Se aplica a

Consulte también