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HtmlSelect.ClearSelection Метод

  • Ссылка

Определение

Пространство имен:
System.Web.UI.HtmlControls
Сборка:
System.Web.dll

Отменяет выбор в списке элемента управления HtmlSelect и задает значение свойства Selected всех элементов равным false.

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

Примеры

В следующем примере кода показано, как переопределить ClearSelection метод в пользовательском серверном элементе управления, чтобы он всегда очищал все выбранные элементы HtmlSelect коллекции.

<%@ 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

Комментарии

Метод ClearSelection выполняет итерацию по ListItemCollection коллекции, представленной свойством HtmlSelect элемента управления Items , и задает Selected свойству каждого ListItem объекта значение false.

Применяется к

См. также раздел