TreeNode::Expanded Property
Gets or sets a value that indicates whether the node is expanded.
Assembly: System.Web (in System.Web.dll)
Use the Expanded property to specify or determine whether the node is expanded.
You can expand and collapse a node by calling the Expand and Collapse methods, respectively. You can also expand and collapse a node and all its child nodes by calling the ExpandAll and CollapseAll methods, respectively.
Since the Expanded property is a tri-state property, the following C# code snippet causes a compile error:
protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e)
{
if (TreeView1.Nodes[0].Expanded)
{
// some work here
}
}
While VB.Net implicitly casts the Boolean value to a NullableBoolean, C# does not. Therefore, it is a best practice to explicitly check the state of the property. For example, the following code examples in Visual Basic and C# explicitly test the value of the Expanded property.
The following Visual Basic code example explicitly tests the value of the Expanded property. This example tests if the Expanded property is set to True; therefore Nothing and False fall through the If statement.
If TreeView1.Nodes(0).Expanded = True Then 'some work hereEnd IF
This C# code example explicitly tests the value of the Expanded property. This example tests if the Expanded property is set to True; therefore Null and False fall through the If statement.
if( TreeView1.Nodes[0].Expanded == true ) { //some work here}
| Topic | Location |
|---|---|
| How to: Add or Delete TreeView Node Elements (Visual Studio) | Building ASP .NET Web Applications in Visual Studio |
The following code example demonstrates how to use the Expanded property to programmatically expand a node. It initializes all nodes with a depth of one to an expanded state. Notice that when the root node is expanded, its child nodes are already expanded. For this example to work correctly, you must copy the sample XML data below to a file named Book.xml.
The following code is sample XML data for the previous example.
<Book Title="Book Title">
<Chapter Heading="Chapter 1">
<Section Heading="Section 1">
</Section>
<Section Heading="Section 2">
</Section>
</Chapter>
<Chapter Heading="Chapter 2">
<Section Heading="Section 1">
</Section>
</Chapter>
</Book>
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.