The NodeCollapse event is fired upon collapsing TreeNodes (clicking the "-" icon in front of the nodes).
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The NodeCollapse event fires only when load on demand is used - meaning only when the ExpandMode property of the respective TreeNode is set to ExpandMode.ServerSide. |
The most common approach is loading nodes on demand and clearing them upon collapsing. An example is shown below:
Example:
| ASPX |
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<rad:RadTreeView
ID="RadTreeView1"
runat="server"
OnNodeCollapse="RadTreeView1_NodeCollapse"
OnNodeExpand="RadTreeView1_NodeExpand">
<Nodes>
<rad:RadTreeNode runat="server" ExpandMode="ServerSide" Text="New Item1">
</rad:RadTreeNode>
<rad:RadTreeNode runat="server" ExpandMode="ServerSide" Text="New Item2">
</rad:RadTreeNode>
</Nodes>
</rad:RadTreeView>
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| C# |
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protected void RadTreeView1_NodeExpand(object o, Telerik.WebControls.RadTreeNodeEventArgs e)
{
e.NodeClicked.Nodes.Add(new RadTreeNode("child1"));
e.NodeClicked.Nodes.Add(new RadTreeNode("child2"));
}
protected void RadTreeView1_NodeCollapse(object o, Telerik.WebControls.RadTreeNodeEventArgs e)
{
e.NodeClicked.Nodes.Clear();
}
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| VB.NET |
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Protected Sub RadTreeView1_NodeExpand(ByVal o As Object, ByVal e As Telerik.WebControls.RadTreeNodeEventArgs)
e.NodeClicked.Nodes.Add(New RadTreeNode("child1"))
e.NodeClicked.Nodes.Add(New RadTreeNode("child2"))
End Sub
Protected Sub RadTreeView1_NodeCollapse(ByVal o As Object, ByVal e As Telerik.WebControls.RadTreeNodeEventArgs)
e.NodeClicked.Nodes.Clear
End Sub
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Note: You should keep into account that the NodeCollapse event can be only applied to nodes loaded on the server-side. Therefore, you should load the nodes on the server-side (ExpandMode.ServerSide). |