DxTreeList.FocusedRowChanged Event

Fires when row focus changes.

Namespace: DevExpress.Blazor

Assembly: DevExpress.Blazor.v24.1.dll

NuGet Package: DevExpress.Blazor

Declaration

[Parameter]
public EventCallback<TreeListFocusedRowChangedEventArgs> FocusedRowChanged { get; set; }

Parameters

Type	Description
TreeListFocusedRowChangedEventArgs	An object that contains data for this event.

Remarks

When the FocusedRowEnabled property is set to true, the TreeList displays the focused row. Use the FocusedRowChanged event to handle focused row changes. The following event argument properties allow you to get information about the focused row.

VisibleIndex

If a data row is focused, this property returns this row’s visible index. The property returns -1 if the TreeList displays no rows.

DataItem

If a data row is focused, this property returns the data item bound to this row. The property returns null if the TreeList displays no rows.

The FocusedRowChanged event fires in the following cases:

• A user clicks a row to focus it.
• You call the SetFocusedRowIndex(Int32) method.
• The TreeList moves focus to a row on the initial load or when visible rows change (for instance, when you apply a filter or sorting or a page changes).

Run Demo: TreeList - Focused Row

In the following code snippet, the TreeList component displays additional information about the focused space object:

Razor

@inject SpaceObjectDataProvider SpaceObjectDataProvider

<DxTreeList Data="TreeListData"
            ChildrenFieldName="Satellites"
            FocusedRowEnabled="true"
            FocusedRowChanged="TreeList_FocusedRowChanged">
    <Columns>
        <DxTreeListDataColumn FieldName="Name" />
        <DxTreeListDataColumn FieldName="TypeOfObject" Caption="Type" />
        <DxTreeListDataColumn FieldName="Mass10pow21kg" Caption="Mass, kg" DisplayFormat="N2">
            <HeaderCaptionTemplate>Mass, 10<sup>21</sup> &#215; kg</HeaderCaptionTemplate>
        </DxTreeListDataColumn>
        <DxTreeListDataColumn FieldName="MeanRadiusInKM" Caption="Radius, km" DisplayFormat="N2" />
        <DxTreeListDataColumn FieldName="Volume10pow9KM3" DisplayFormat="N2">
            <HeaderCaptionTemplate>Volume, 10<sup>9</sup> &#215; km<sup>3</sup></HeaderCaptionTemplate>
        </DxTreeListDataColumn>
        <DxTreeListDataColumn FieldName="SurfaceGravity" DisplayFormat="N2">
            <HeaderCaptionTemplate>Gravity, m/s<sup>2</sup></HeaderCaptionTemplate>
        </DxTreeListDataColumn>
    </Columns>
</DxTreeList>

@if (FocusedSpaceObject != null) {
    <h5>@FocusedSpaceObject.Name</h5>
    <ul>
        <li><b>Radius</b>: @FocusedSpaceObject.MeanRadiusInKM.ToString("N2") km</li>
        <li><b>Density</b>: @FocusedSpaceObject.Density.ToString("N2") g/cm<sup>3</sup></li>
        <li><b>Gravity</b>: @FocusedSpaceObject.SurfaceGravity.ToString("N2") m/s<sup>2</sup></li>
    </ul>
}

@code {
    object TreeListData { get; set; }
    SpaceObject FocusedSpaceObject { get; set; }

    protected override async Task OnInitializedAsync() {
        TreeListData = SpaceObjectDataProvider.GenerateData();
    }
    void TreeList_FocusedRowChanged(TreeListFocusedRowChangedEventArgs e) {
        FocusedSpaceObject = e.DataItem as SpaceObject;
    }
}

SpaceObject

using System.Collections.Generic;

public class SpaceObject {
    public string Name { get; set; }
    public double MeanRadiusInKM { get; set; }
    public double Volume10pow9KM3 { get; set; }
    public double Mass10pow21kg { get; set; }
    public double Density { get; set; }
    public double SurfaceGravity { get; set; }
    public string TypeOfObject { get; set; }
    public List<SpaceObject> Satellites { get; set; }
    public SpaceObject(
        string name,
        double meanRadiusInKM,
        double volume10pow9KM3,
        double mass10pow21kg,
        double density,
        double surfaceGravity,
        string typeOfObject,
        List<SpaceObject> satellites = null
    ) {
        Name = name;
        MeanRadiusInKM = meanRadiusInKM;
        Volume10pow9KM3 = volume10pow9KM3;
        Mass10pow21kg = mass10pow21kg;
        Density = density;
        SurfaceGravity = surfaceGravity;
        TypeOfObject = typeOfObject;
        Satellites = satellites ?? new List<SpaceObject>();
    }
}

SpaceObjectDataProvider

public class SpaceObjectDataProvider {
    public List<SpaceObject> GenerateData() {
        return new List<SpaceObject>() {
            new SpaceObject("Sun", 696000, 1412000000, 1989100000, 1.409, 274.0, "Star", new List<SpaceObject>() {
                new SpaceObject("Mercury", 2439.7, 60.83, 330.2, 5.43, 3.7, "Planet"),
                new SpaceObject("Venus", 6051.8, 928.43, 4868.5, 5.24, 8.872, "Planet"),
                new SpaceObject("Earth", 6371.0, 1083.21, 5973.6, 5.515, 9.78033, "Planet", new List<SpaceObject> () {
                    new SpaceObject("Moon", 1737.1, 21.958, 73.5, 3.3464, 1.625, "Satellite")
                }),
                new SpaceObject("Mars", 3390.0, 163.18, 641.85, 3.94, 3.7, "Planet"),
                new SpaceObject("Jupiter", 69911, 1431280, 1898600, 1.33, 24.79, "Planet", new List<SpaceObject>() {
                    new SpaceObject("Ganymede", 2631.2, 76.30, 148.2, 1.936, 1.428, "Satellite"),
                    new SpaceObject("Callisto", 2410.3, 58.65, 107.6, 1.83, 1.23603, "Satellite"),
                    new SpaceObject("Io", 1821.5, 25.32, 89.3, 3.528, 1.797, "Satellite"),
                    new SpaceObject("Europa", 1561, 15.93, 48, 3.01, 1.316, "Satellite"),
                }),
                new SpaceObject("Saturn", 58232, 827130, 568460, 0.70, 10.445, "Planet", new List<SpaceObject>() {
                    new SpaceObject("Titan", 2576, 71.52, 134.5, 1.88, 1.354, "Satellite"),
                    new SpaceObject("Rhea", 764.4, 1.87, 2.3166, 1.23, 0.26, "Satellite"),
                    new SpaceObject("Iapetus", 736, 1.55, 1.9739, 1.08, 0.223, "Satellite"),
                    new SpaceObject("Dione", 561.6, 0.73, 1.096, 1.48, 0.232, "Satellite"),
                    new SpaceObject("Tethys", 533, 0.624, 0.6173, 1.15, 0.145, "Satellite"),
                    new SpaceObject("Enceladus", 252.1, 0.067, 0.108, 1.61, 0.111, "Satellite"),
                    new SpaceObject("Mimas", 198.3, 0.033, 0.03749, 1.15, 0.06363, "Satellite")
                }),
                new SpaceObject("Uranus", 25362, 68340, 86832, 1.30, 8.87, "Planet", new List<SpaceObject>() {
                    new SpaceObject("Titania", 788.9, 2.06, 3.526, 1.72, 0.378, "Satellite"),
                    new SpaceObject("Oberon", 761.4, 1.85, 3.014, 1.63, 0.347, "Satellite"),
                    new SpaceObject("Umbriel", 584.7, 0.84, 1.2, 1.4, 0.234, "Satellite"),
                    new SpaceObject("Ariel", 578.9, 0.81, 1.35, 1.67, 0.269, "Satellite"),
                    new SpaceObject("Miranda", 235.8, 0.055, 0.0659, 1.20, 0.07910375, "Satellite"),
                }),
                new SpaceObject("Neptune", 24622, 62540, 102430, 1.76, 11.15, "Planet", new List<SpaceObject>() {
                    new SpaceObject("Triton", 1353.4, 10.38, 21.5, 2.061, 0.782, "Satellite"),
                    new SpaceObject("Proteus", 210, 0.038, 0.050, 1.3, 0.0666, "Satellite"),
                }),
                new SpaceObject("Eris", 1170, 7, 16.7, 2.25, 0.662, "Dwarf planet"),
                new SpaceObject("Pluto", 1153, 7.15, 13.105, 2.0, 0.61, "Dwarf planet"),
                new SpaceObject("Makemake", 710, 1.8, 3, 2.0, 0.4,  "Dwarf planet"),
                new SpaceObject("Haumea", 575, 1.3, 4.006, 3, 0.44, "Dwarf planet"),
                new SpaceObject("Ceres", 475, 0.437, 0.95, 2.08, 0.27, "Dwarf planet"),
                new SpaceObject("Pallas", 266, 0.078, 0.211, 2.8, 0.2, "Asteroid"),
                new SpaceObject("Vesta", 264.6, 0.078, 0.262, 3.42, 0.251, "Asteroid")
            })
        };
    }
}

Program.cs

// ...
builder.Services.AddSingleton<SpaceObjectDataProvider>();

For more information about row focus in the TreeList component, refer to the following topic: Selection and Focus in Blazor TreeList.