TreeListFooterCommandContext Class

Contains contextual information for a TreeList footer context menu.

Namespace: DevExpress.Blazor

Assembly: DevExpress.Blazor.v25.2.dll

NuGet Package: DevExpress.Blazor

Declaration

public class TreeListFooterCommandContext :
    GridFooterCommandContextBase,
    ITreeListCommandContext,
    ICommandContextBase

Remarks

The DevExpress Blazor TreeList allows you to display context menus with predefined and custom commands. Use the ContextMenus property to activate context menus for specific TreeList elements.

Run Demo: Context Menu

Handle the CustomizeContextMenu event to modify the menu item collection. Use the Context event argument to identify the target TreeList element and obtain contextual information.

Target Element	Context Type	Contextual information
Any	ITreeListCommandContext	TreeList
Data Row	TreeListDataRowCommandContext	TreeList, Column, DataItem, RowVisibleIndex
Footer	TreeListFooterCommandContext	TreeList, Column, SummaryItems
Header	TreeListHeaderCommandContext	TreeList, Column

Example

The following example adds context commands that display/hide total summaries:

Razor

@inject EmployeeTaskService EmployeeTaskService

<DxTreeList Data="TreeListData"
            PageSize="5"
            KeyFieldName="Id"
            ParentKeyFieldName="ParentId"
            FooterDisplayMode="TreeListFooterDisplayMode.Always"
            ContextMenus="TreeListContextMenus.Footer"
            CustomizeContextMenu="CustomizeContextMenu">
    <Columns>
        <DxTreeListSelectionColumn Width="80px" />
        <DxTreeListDataColumn FieldName="Name" Caption="Task" ShowInColumnChooser="false" />
        <DxTreeListDataColumn FieldName="EmployeeName" />
        <DxTreeListDataColumn FieldName="StartDate" />
        <DxTreeListDataColumn FieldName="DueDate" />
    </Columns>
    <TotalSummary>
        @foreach (var item in SummaryItems) {
            <DxTreeListSummaryItem FieldName="@item.FieldName"
                                   SummaryType="item.Type"
                                   ValueDisplayFormat="@item.DisplayFormat"
                                   @key="item" />
        }
    </TotalSummary>
</DxTreeList>

@code {
    List<EmployeeTask> TreeListData { get; set; }

    IList<SummaryItem> SummaryItems { get; set; }
    static readonly TreeListSummaryItemType[] SummaryTypes = Enum.GetValues<TreeListSummaryItemType>()
        .Where(s => s != TreeListSummaryItemType.None && s != TreeListSummaryItemType.Custom && s != TreeListSummaryItemType.Sum)
        .ToArray();
    bool IsStringColumn(string fieldName) => new[] { "Name", "EmployeeName" }.Contains(fieldName);

    record SummaryItem(string FieldName, TreeListSummaryItemType Type) {
        public string DisplayFormat { get; init; }
    }

    protected override void OnInitialized() {
        TreeListData = EmployeeTaskService.GenerateData();
        SummaryItems = new List<SummaryItem>([
            new SummaryItem("DueDate", TreeListSummaryItemType.Count),
        ]);
    }
    void CustomizeContextMenu(TreeListCustomizeContextMenuEventArgs args) {
        ITreeListColumn column = null;
        IReadOnlyList<ITreeListSummaryItem> contextSummaryItems = null;
        IList<SummaryItem> summaryItemsCollection = null;

        if (args.Context is TreeListFooterCommandContext footerCommandContext) {
            column = footerCommandContext.Column;
            contextSummaryItems = footerCommandContext.SummaryItems;
            summaryItemsCollection = SummaryItems;
        }
        if (column != null && column is ITreeListDataColumn dataColumn) {
            foreach (var summaryType in SummaryTypes) {
                var fieldName = dataColumn.FieldName;
                if (IsStringColumn(fieldName) && summaryType != TreeListSummaryItemType.Count)
                    continue;
                var existingItem = contextSummaryItems.FirstOrDefault(i => i.FieldName == fieldName && i.SummaryType == summaryType);
                var menuItem = args.Items.AddCustomItem(summaryType.ToString(), () => OnSummaryCommand(dataColumn, summaryType, summaryItemsCollection));
            }
        }
    }
    void OnSummaryCommand(ITreeListDataColumn dataColumn, TreeListSummaryItemType summaryType, IList<SummaryItem> summaryItemsCollection) {
        var fieldName = dataColumn.FieldName;
        var existingItem = summaryItemsCollection.FirstOrDefault(i => i.FieldName == fieldName && i.Type == summaryType);
        if (existingItem != null)
            summaryItemsCollection.Remove(existingItem);
        else
            summaryItemsCollection.Add(new SummaryItem(fieldName, summaryType) {
                DisplayFormat = summaryType == TreeListSummaryItemType.Count ? null : dataColumn.DisplayFormat
            });
        StateHasChanged();
    }
}

EmployeeTask.cs

public class EmployeeTask {
    public int Id { get; set; }
    public int ParentId { get; set; }
    public string Name { get; set; }
    public string EmployeeName { get; set; }
    public DateTime StartDate { get; set; }
    public DateTime DueDate { get; set; }
    public int Progress { get; set; }
    public EmployeeTask() { }
    public EmployeeTask(
        int id,
        int parentId,
        string name,
        string employeeName,
        DateTime startDate,
        DateTime dueDate,
        int progress
        )
    {
        Id = id;
        ParentId = parentId;
        Name = name;
        EmployeeName = employeeName;
        StartDate = startDate;
        DueDate = dueDate;
        Progress = progress;
    }
}

EmployeeTaskService.cs

public class EmployeeTaskService {
    public List<EmployeeTask> GenerateData() {
        return new List<EmployeeTask>() {
            new EmployeeTask(1, 0, "Simplify & Clarify Product Messaging", "John Heart", new DateTime(2018, 4, 3), new DateTime(2018, 4, 14), 14),
            new EmployeeTask(2, 1, "Prepare Financial Reports", "Samantha Bright", new DateTime(2018, 4, 3), new DateTime(2018, 4, 7), 17),
            new EmployeeTask(3, 1, "Prepare Marketing Plan", "Arthur Miller", new DateTime(2018, 4, 7), new DateTime(2018, 4, 14), 11),
            new EmployeeTask(4, 0, "Create Action Plan to Improve Customer Engagement", "Robert Reagan", new DateTime(2017, 8, 8), new DateTime(2018, 4, 8), 23),
            new EmployeeTask(5, 4, "Update Personnel Files", "Greta Sims", new DateTime(2017, 8, 8), new DateTime(2017, 10, 18), 100),
            new EmployeeTask(6, 4, "Review Health Insurance Options", "Brett Wade", new DateTime(2017, 9, 27), new DateTime(2017, 11, 10), 37),
            new EmployeeTask(7, 4, "Choose Between PPO and HMO Health Plan", "Sandra Johnson", new DateTime(2017, 12, 13), new DateTime(2018, 3, 23), 17),
            new EmployeeTask(8, 4, "Update Google Adwords Strategy", "Ed Holmes", new DateTime(2017, 8, 23), new DateTime(2017, 12, 23), 45),
            new EmployeeTask(9, 4, "Create New Brochure Design", "Barb Banks", new DateTime(2018, 1, 3), new DateTime(2018, 3, 14), 17),
            new EmployeeTask(10, 4, "Obtain Price Quote for New Brochure", "Kevin Carter", new DateTime(2018, 2, 1), new DateTime(2018, 3, 15), 18),
            new EmployeeTask(11, 4, "Brochure Design Review", "Cindy Stanwick", new DateTime(2017, 8, 22), new DateTime(2017, 10, 28), 4),
            new EmployeeTask(12, 4, "Review Website Redesign Strategy", "Sammy Hill", new DateTime(2017, 9, 16), new DateTime(2018, 3, 6), 73),
            new EmployeeTask(13, 4, "Roll Out New Website", "Davey Jones", new DateTime(2017, 11, 7), new DateTime(2018, 2, 6), 9),
            new EmployeeTask(14, 4, "Update Sales/Marketing Strategy", "Victor Norris", new DateTime(2017, 12, 13), new DateTime(2018, 4, 2), 5),
            new EmployeeTask(15, 4, "Update Sales/Revenue Report", "Mary Stern", new DateTime(2017, 12, 25), new DateTime(2018, 4, 2), 4),
            new EmployeeTask(16, 4, "Direct vs Online Sales Comparison Report", "Robin Cosworth", new DateTime(2018, 1, 2), new DateTime(2018, 3, 20), 14),
            new EmployeeTask(17, 4, "Review Sales Report and Approve Modifications", "Kelly Rodriguez", new DateTime(2017, 9, 4), new DateTime(2017, 10, 30), 8),
            new EmployeeTask(18, 4, "Update R&D Strategy", "James Anderson", new DateTime(2017, 11, 13), new DateTime(2017, 12, 4), 12),
            new EmployeeTask(19, 4, "Discuss Updated R&D Strategy", "Antony Remmen", new DateTime(2017, 10, 29), new DateTime(2017, 12, 31), 14),
            new EmployeeTask(20, 4, "Update QA Strategy", "Olivia Peyton", new DateTime(2017, 10, 31), new DateTime(2017, 11, 2), 18),
            new EmployeeTask(21, 4, "Schedule Training Events", "Taylor Riley", new DateTime(2017, 11, 19), new DateTime(2018, 4, 7), 21),
            new EmployeeTask(22, 4, "Approve Hiring of John Jeffers", "Amelia Harper", new DateTime(2018, 1, 7), new DateTime(2018, 4, 8), 10),
            new EmployeeTask(23, 0, "Increase Average Subscription Price", "Wally Hobbs", new DateTime(2017, 8, 9), new DateTime(2017, 9, 13), 96),
            new EmployeeTask(24, 23, "Update Non-Compete Agreements", "Brad Jameson", new DateTime(2017, 8, 9), new DateTime(2017, 9, 3), 96),
            new EmployeeTask(25, 23, "Update Employee Records with New NDA", "Karen Goodson", new DateTime(2017, 8, 23), new DateTime(2018, 9, 10), 100)
        };
    }
}

Program.cs

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

Run Demo: Context Menu

Implements

ITreeListCommandContext

ICommandContextBase

Inheritance

Object

DevExpress.Blazor.Grid.Internal.Base.ContextMenu.GridCommandContextBase

DevExpress.Blazor.Grid.Internal.Base.ContextMenu.GridHeaderCommandContextBase

DevExpress.Blazor.Grid.Internal.Base.ContextMenu.GridFooterCommandContextBase

TreeListFooterCommandContext