Data Binding - Virtual Mode

In addition to bound and unbound modes, the ASPxTreeList can operate in Virtual Mode. This mode can be useful when binding to large data sets.

In virtual mode a tree is created on demand. In this instance, child nodes are created and initialized when their parent node is expanded.

The ASPxTreeList fires two events that you should process in code. These include:

• VirtualModeCreateChildren;
• VirtualModeNodeCreating.

Within the VirtualModeCreateChildren event handler you should create a list of business objects that correspond to the child nodes owned by the processed node.

The VirtualModeNodeCreating event is raised for each node object created within the VirtualModeCreateChildren event handler. This event enables you to initialize the corresponding node in a tree. Here you should specify the node's key value and cell values. If you are certain that the processed node has no child nodes, set the event parameter's e.IsLeaf property to true.

In this demo, the ASPxTreeList control uses this data binding method to display the file/folder tree of this demo web site.