TreeListView.ChildNodesSelector Property

Gets or sets a selector that returns the list of child nodes for the processed node. This is a dependency property.

Namespace: DevExpress.Xpf.Grid

Assembly: DevExpress.Xpf.Grid.v23.2.dll

NuGet Package: DevExpress.Wpf.Grid.Core

Declaration

C#

public IChildNodesSelector ChildNodesSelector { get; set; }

VB.NET

Public Property ChildNodesSelector As IChildNodesSelector

Property Value

Type	Description
IChildNodesSelector	The child nodes selector.

Remarks

Run Demo: Child Nodes Selector View Example: Use the Child Nodes Selector to Display Hierarchical Data

Use the Child Nodes Selector to create a hierarchical data structure in the TreeListView. An example of this structure is shown below:

C#

public class ProjectObject : BaseObject {
    public ObservableCollection<ProjectStage> Stages { get; set; }
}

public class ProjectStage : BaseObject {
    public ObservableCollection<Task> Tasks { get; set; }
}

public class Task : BaseObject {
    State state;
    // ...
}

VB.NET

Public Class ProjectObject
    Inherits BaseObject

    Public Property Stages As ObservableCollection(Of ProjectStage)
End Class

Public Class ProjectStage
    Inherits BaseObject

    Public Property Tasks As ObservableCollection(Of Task)
End Class

Public Class Task
    Inherits BaseObject

    Private state As State
    ' ...
End Class 

1. Create a selector class that implements IChildNodesSelector, and override the SelectChildren(Object) method that returns node children.

   For the Project-Stage-Task class structure, the selector class is as follows:

   C#

   public class CustomChildrenSelector : IChildNodesSelector {
       public IEnumerable SelectChildren(object item) {
           if (item is ProjectStage)
               return ((ProjectStage)item).Tasks;
           else if (item is ProjectObject)
               return ((ProjectObject)item).Stages;
           return null;
       }
   }
   

   VB.NET

   Public Class CustomChildrenSelector
       Inherits IChildNodesSelector
   
       Public Function SelectChildren(ByVal item As Object) As IEnumerable
           If TypeOf item Is ProjectStage Then
               Return (CType(item, ProjectStage)).Tasks
           ElseIf TypeOf item Is ProjectObject Then
               Return (CType(item, ProjectObject)).Stages
           End If
   
           Return Nothing
       End Function
   End Class 
   

2. Assign the Child Nodes Selector to the ChildNodesSelector property.

3. Set the TreeListView.TreeDerivationMode property to ChildNodesSelector.

   XAML

   <dxg:TreeListControl ...>
       <dxg:TreeListControl.Resources>
           <local:CustomChildrenSelector x:Key="childrenSelector"/>
       </dxg:TreeListControl.Resources>
       <dxg:TreeListControl.View>
           <dxg:TreeListView TreeDerivationMode="ChildNodesSelector"
                             ChildNodesSelector="{StaticResource childrenSelector}"/>
       </dxg:TreeListControl.View>
   </dxg:TreeListControl>
   

Tip

If all objects have the same children field, assign its name to the TreeListView.ChildNodesPath property. Otherwise, create a Child Nodes Selector.

Refer to the following help topic for more information: Bind to Hierarchical Data Structure.

Related GitHub Examples

The following code snippets (auto-collected from DevExpress Examples) contain references to the ChildNodesSelector property.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

XAML

wpf-spreadsheetcontrol-api-part-3/CS/SpreadsheetControl_WPF_API_Part03/MainWindow.xaml#L59

<dxg:TreeListControl.View>
    <dxg:TreeListView x:Name="view" TreeDerivationMode="ChildNodesSelector" ChildNodesSelector="{StaticResource childrenSelector}" ShowIndicator="False" ShowColumnHeaders="False" AutoWidth="True" AllowPerPixelScrolling="False" CustomColumnDisplayText="view_CustomColumnDisplayText" />
</dxg:TreeListControl.View>

wpf-spreadsheet-pivot-table-api-examples/CS/SpreadsheetWPFPivotTableExamples/MainWindow.xaml#L52

<dxg:TreeListControl.View>
    <dxg:TreeListView x:Name="view" TreeDerivationMode="ChildNodesSelector" ChildNodesSelector="{StaticResource childrenSelector}" ShowIndicator="False" ShowColumnHeaders="False" AutoWidth="True" AllowPerPixelScrolling="False" CustomColumnDisplayText="view_CustomColumnDisplayText" />
</dxg:TreeListControl.View>

wpf-richedit-document-api/CS/DXRichEditControlAPISample/MainWindow.xaml#L57

<dxg:TreeListControl.View>
    <dxg:TreeListView x:Name="view" TreeDerivationMode="ChildNodesSelector" ChildNodesSelector="{StaticResource childrenSelector}" ShowIndicator="False" ShowColumnHeaders="False" AutoWidth="True" AllowPerPixelScrolling="False" CustomColumnDisplayText="view_CustomColumnDisplayText" />
</dxg:TreeListControl.View>

wpf-spreadsheet-chart-api/CS/SpreadsheetWPFChartAPISamples/MainWindow.xaml#L52

<dxg:TreeListControl.View>
    <dxg:TreeListView x:Name="view" TreeDerivationMode="ChildNodesSelector" ChildNodesSelector="{StaticResource childrenSelector}" ShowIndicator="False" ShowColumnHeaders="False" AutoWidth="True" AllowPerPixelScrolling="False" CustomColumnDisplayText="view_CustomColumnDisplayText" />
</dxg:TreeListControl.View>