Instead of loading the entire directory structure on application startup, this control loads directories on demand (when a user expands a specific directory). The navigationTreeList control in this demo displays directories of the file system.
DEVEXPRESS TREELIST HOW TO
The following demo shows how to use the TreeList.VirtualTreeGetChildNodes and TreeList.VirtualTreeGetCellValue events to specify data for a Tree List control. The VirtualTreeGetChildNodes event fires on demand.įor more information and examples, see Virtual Mode (Dynamic Data Loading) Using Events (Tree List Level). To respond to an end-user changing node cells, handle the TreeList.VirtualTreeSetCellValue event. Then handle the VirtualTreeGetChildNodes and TreeList.VirtualTreeGetCellValue events, to provide data. To implement this data loading mode, set the TreeList.DataSource property to any object, except objects that implement the IList or IVirtualTreeListData interface. Please refer to Virtual Mode (Dynamic Data Loading) Using Events (Tree List Level) to learn more.Ī Tree List control supports dynamic data loading.
The TreeList.VirtualTreeGetChildNodes, TreeList.VirtualTreeGetCellValue and TreeList.VirtualTreeSetCellValue events support dynamic data loading. Gets an instance of the business object being currently processed. Gets or sets the collection of children for the currently processed business object. The following properties provide information specific to this event: However, you can perform these operations in code.The VirtualTreeGetChildNodes event's data class is VirtualTreeGetChildNodesInfo. When column headers are hidden, an end-user cannot perform data sorting and filtering.The following features are disabled in the TreeView style: TreeListOptionsView.ShowIndicator is set to false TreeListOptionsView.ShowHorzLines, TreeListOptionsView.ShowVertLines and TreeListOptionsView.ShowFirstLines are set to false TreeListOptionsView.ShowColumns is set to false When you activate the TreeView style, certain TreeList properties are modified to imitate this visual style. The TreeList control will only display a single column specified by the TreeViewColumn/ TreeViewFieldName property. To display single-column data in the TreeView style, leave the TreeList.ViewStyle property set to Default (or set it explicitly to TreeView) and then specify the display column with the TreeList.TreeViewColumn or TreeList.TreeViewFieldName property.The TreeList control will display all visible columns from the TreeList.VisibleColumns collection. To display multi-column data in the TreeView style, set the TreeList.ViewStyle property to TreeView.The TreeView visual style can be activated using one of the following methods: To learn how to provide data for the TreeList control and organize it into a hierarchy, see Data Binding. Unlike the standard TreeView control which can only display single-column data, the TreeList control can display single-column and multi-column data in the TreeView visual style. The latter imitates the standard TreeView control’s appearance, which is characterized by the following features: The TreeList control allows you to choose between the default TreeList and TreeView visual styles.
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