TreeView.TreeNodeCheckChanged TreeView.TreeNodeCheckChanged TreeView.TreeNodeCheckChanged TreeView.TreeNodeCheckChanged Event

Definizione

Si verifica quando lo stato di una casella di controllo nel controllo TreeView viene modificato tra gli invii al server.Occurs when a check box in the TreeView control changes state between posts to the server.

public:
 event System::Web::UI::WebControls::TreeNodeEventHandler ^ TreeNodeCheckChanged;
public event System.Web.UI.WebControls.TreeNodeEventHandler TreeNodeCheckChanged;
member this.TreeNodeCheckChanged : System.Web.UI.WebControls.TreeNodeEventHandler 
Public Custom Event TreeNodeCheckChanged As TreeNodeEventHandler 

Esempi

Nell'esempio di codice riportato di seguito viene illustrato TreeNodeCheckChanged come utilizzare l'evento Label per aggiornare un controllo quando TreeView le caselle di controllo del controllo cambiano stato tra gli invii al server.The following code example demonstrates how to use the TreeNodeCheckChanged event to update a Label control when the check boxes of the TreeView control change state between posts to the server.


<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  void LinksTreeView_CheckChanged(Object sender, TreeNodeEventArgs e)
  {

    if(LinksTreeView.CheckedNodes.Count > 0)
    {

      // Clear the message label.
      Message.Text = "You selected: <br /><br />";

      // Iterate through the CheckedNodes collection and display 
      // the selected nodes.
      foreach (TreeNode node in LinksTreeView.CheckedNodes)
      {

        Message.Text += node.Text + "<br />";

      }

    }

    else
    {

      Message.Text = "No items selected.";

    }

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>TreeView CheckChanged Example</title>
</head>
<body>
    <form id="form1" runat="server">
    
      <h3>TreeView CheckChanged Example</h3>
    
      <!-- Set the ShowCheckBoxes property declaratively.   -->
      <!-- Because the ShowCheckBoxes property uses a flag  -->
      <!-- enumeration, you can combine multiple values by  -->
      <!-- using the bitwise OR operator. In declarative    -->
      <!-- syntax, this is done using a comma separated     -->
      <!-- list.                                            -->  
      <asp:TreeView id="LinksTreeView"
        ForeColor="Blue"
        ExpandDepth="2"
        ShowCheckBoxes="Parent,Leaf" 
        OnTreeNodeCheckChanged="LinksTreeView_CheckChanged" 
        runat="server">
         
        <LevelStyles>
        
          <asp:TreeNodeStyle ChildNodesPadding="10" 
            Font-Bold="true" 
            Font-Size="12pt" 
            ForeColor="DarkGreen"/>
          <asp:TreeNodeStyle ChildNodesPadding="5" 
            Font-Bold="true" 
            Font-Size="10pt"/>
          <asp:TreeNodeStyle ChildNodesPadding="5" 
            Font-UnderLine="true" 
            Font-Size="10pt"/>
          <asp:TreeNodeStyle ChildNodesPadding="10" 
            Font-Size="8pt"/>
             
        </LevelStyles>
         
        <Nodes>
        
          <asp:TreeNode Text="Table of Contents"
            SelectAction="None">
             
            <asp:TreeNode Text="Chapter One">
            
              <asp:TreeNode Text="Section 1.0">
              
                <asp:TreeNode Text="Topic 1.0.1"/>
                <asp:TreeNode Text="Topic 1.0.2"/>
                <asp:TreeNode Text="Topic 1.0.3"/>
              
              </asp:TreeNode>
              
              <asp:TreeNode Text="Section 1.1">
              
                <asp:TreeNode Text="Topic 1.1.1"/>
                <asp:TreeNode Text="Topic 1.1.2"/>
                <asp:TreeNode Text="Topic 1.1.3"/>
                <asp:TreeNode Text="Topic 1.1.4"/>
              
              </asp:TreeNode>
            
            </asp:TreeNode>
            
            <asp:TreeNode Text="Chapter Two">
            
              <asp:TreeNode Text="Section 2.0">
              
                <asp:TreeNode Text="Topic 2.0.1"/>
                <asp:TreeNode Text="Topic 2.0.2"/>
              
              </asp:TreeNode>
            
            </asp:TreeNode>
            
          </asp:TreeNode>
          <asp:TreeNode Text="Appendix A" />
          <asp:TreeNode Text="Appendix B" />
          <asp:TreeNode Text="Appendix C" />
        
        </Nodes>
        
      </asp:TreeView>
      
      <br /><br />
      
      <asp:Button id="Submit"
        Text="Select Items"
        runat="server"/>
         
      <br /><br />
      
      <asp:Label id="Message"
        runat="server"/>

    </form>
  </body>
</html>


<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  Sub LinksTreeView_CheckChanged(ByVal sender As Object, ByVal e As TreeNodeEventArgs)

    If LinksTreeView.CheckedNodes.Count > 0 Then

      ' Clear the message label.
      Message.Text = "You selected: <br /><br />"

      ' Iterate through the CheckedNodes collection and display 
      ' the selected nodes.
      Dim node As TreeNode

      For Each node In LinksTreeView.CheckedNodes

        Message.Text &= node.Text & "<br />"

      Next

    Else

      Message.Text = "No items selected."

    End If

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>TreeView CheckChanged Example</title>
</head>
<body>
    <form id="form1" runat="server">
    
      <h3>TreeView CheckChanged Example</h3>
    
      <!-- Set the ShowCheckBoxes property declaratively.   -->
      <!-- Because the ShowCheckBoxes property uses a flag  -->
      <!-- enumeration, you can combine multiple values by  -->
      <!-- using the bitwise OR operator. In declarative    -->
      <!-- syntax, this is done using a comma separated     -->
      <!-- list.                                            -->  
      <asp:TreeView id="LinksTreeView"
        ForeColor="Blue"
        ExpandDepth="2"
        ShowCheckBoxes="Parent,Leaf" 
        OnTreeNodeCheckChanged="LinksTreeView_CheckChanged" 
        runat="server">
         
        <LevelStyles>
        
          <asp:TreeNodeStyle ChildNodesPadding="10" 
            Font-Bold="true" 
            Font-Size="12pt" 
            ForeColor="DarkGreen"/>
          <asp:TreeNodeStyle ChildNodesPadding="5" 
            Font-Bold="true" 
            Font-Size="10pt"/>
          <asp:TreeNodeStyle ChildNodesPadding="5" 
            Font-UnderLine="true" 
            Font-Size="10pt"/>
          <asp:TreeNodeStyle ChildNodesPadding="10" 
            Font-Size="8pt"/>
             
        </LevelStyles>
         
        <Nodes>
        
          <asp:TreeNode Text="Table of Contents"
            SelectAction="None">
             
            <asp:TreeNode Text="Chapter One">
            
              <asp:TreeNode Text="Section 1.0">
              
                <asp:TreeNode Text="Topic 1.0.1"/>
                <asp:TreeNode Text="Topic 1.0.2"/>
                <asp:TreeNode Text="Topic 1.0.3"/>
              
              </asp:TreeNode>
              
              <asp:TreeNode Text="Section 1.1">
              
                <asp:TreeNode Text="Topic 1.1.1"/>
                <asp:TreeNode Text="Topic 1.1.2"/>
                <asp:TreeNode Text="Topic 1.1.3"/>
                <asp:TreeNode Text="Topic 1.1.4"/>
              
              </asp:TreeNode>
            
            </asp:TreeNode>
            
            <asp:TreeNode Text="Chapter Two">
            
              <asp:TreeNode Text="Section 2.0">
              
                <asp:TreeNode Text="Topic 2.0.1"/>
                <asp:TreeNode Text="Topic 2.0.2"/>
              
              </asp:TreeNode>
            
            </asp:TreeNode>
            
          </asp:TreeNode>
          <asp:TreeNode Text="Appendix A" />
          <asp:TreeNode Text="Appendix B" />
          <asp:TreeNode Text="Appendix C" />
        
        </Nodes>
        
      </asp:TreeView>
      
      <br /><br />
      
      <asp:Button id="Submit"
        Text="Select Items"
        runat="server"/>
         
      <br /><br />
      
      <asp:Label id="Message"
        runat="server"/>

    </form>
  </body>
</html>

Commenti

L' TreeNodeCheckChanged evento viene generato quando una casella di controllo TreeView nel controllo modifica lo stato tra gli invii al server.The TreeNodeCheckChanged event is raised when a check box in the TreeView control changes state between posts to the server. Questo consente di fornire un metodo di gestione degli eventi che esegue una routine personalizzata, ad esempio l'aggiornamento di un database o il contenuto visualizzato, ogni volta che si verifica questo evento.This allows you to provide an event-handling method that performs a custom routine, such as updating a database or the displayed content, whenever this event occurs.

Anche se l' TreeNodeCheckChanged evento viene generato durante il postback, la modifica di una casella di controllo non comporta un postback.Even though the TreeNodeCheckChanged event is fired on post back, changing a check box does not cause a post back.

Per altre informazioni su come gestire gli eventi, vedere la gestione e generazione di eventi.For more information about how to handle events, see Handling and Raising Events.

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