GridGroupFooterCommandContext Class

Contains contextual information for a Grid group footer context menu.

Namespace: DevExpress.Blazor

Assembly: DevExpress.Blazor.v25.2.dll

Declaration

public class GridGroupFooterCommandContext :
    GridFooterCommandContextBase,
    IGridCommandContext,
    ICommandContextBase

Remarks

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

Run Demo: Context Menu

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

Target Element	Context Type	Contextual information
Any	GridCommandContext	Grid
Data Row	GridDataRowCommandContext	Grid, Column, DataItem, RowVisibleIndex
Footer	GridFooterCommandContext	Grid, Column, SummaryItems
Group Footer	GridGroupFooterCommandContext	Grid, Column, GroupRowVisibleIndex, SummaryItems
Group Panel	GridGroupPanelCommandContext	Grid
Group Row	GridGroupRowCommandContext	Grid, GroupColumn, RowVisibleIndex
Header	GridHeaderCommandContext	Grid, Column

Example

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

Razor

@inject WeatherForecastService ForecastService

<DxGrid Data="@forecasts" 
        ShowGroupPanel="true"
        ContextMenus="GridContextMenus.GroupFooter"
        CustomizeContextMenu="OnCustomizeContextMenu">
    <Columns>
        <DxGridSelectionColumn />
        <DxGridDataColumn FieldName=@nameof(WeatherForecast.TemperatureC) Caption="Temp. (C)" />
        <DxGridDataColumn FieldName=@nameof(WeatherForecast.TemperatureF) Caption="Temp. (F)" />
        <DxGridDataColumn FieldName=@nameof(WeatherForecast.Summary) Caption="Summary" GroupIndex="0" />
        <DxGridDataColumn FieldName=@nameof(WeatherForecast.Date) DisplayFormat="dd/MM/yyyy" />
    </Columns>
    <GroupSummary>
        @foreach (var item in GroupSummaryItems) {
            <DxGridSummaryItem FieldName="@item.FieldName" FooterColumnName="@item.FieldName"
                               SummaryType="item.Type"
                               ValueDisplayFormat="@item.DisplayFormat"
                               @key="item" />
        }
    </GroupSummary>
</DxGrid>

@code {
    string[]? summaries;
    private List<WeatherForecast>? forecasts;
    IList<SummaryItem> GroupSummaryItems { get; set; }

    static readonly GridSummaryItemType[] SummaryTypes = Enum.GetValues<GridSummaryItemType>()
        .Where(s => s != GridSummaryItemType.None && s != GridSummaryItemType.Custom && s != GridSummaryItemType.Sum)
        .ToArray();
    bool IsStringColumn(string fieldName) => new[] { "Summary" }.Contains(fieldName);

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

    protected override async Task OnInitializedAsync() {
        forecasts = await ForecastService.GetForecastAsync();
        summaries = ForecastService.Summaries;
        GroupSummaryItems = new List<SummaryItem>([
            new SummaryItem("TemperatureC", GridSummaryItemType.Count),
        ]);
    }

    void OnCustomizeContextMenu(GridCustomizeContextMenuEventArgs args) {
        IGridColumn column = null;
        IReadOnlyList<IGridSummaryItem> contextSummaryItems = null;
        IList<SummaryItem> summaryItemsCollection = null;

        if (args.Context is GridGroupFooterCommandContext groupFooterCommandContext) {
            column = groupFooterCommandContext.Column;
            contextSummaryItems = groupFooterCommandContext.SummaryItems;
            summaryItemsCollection = GroupSummaryItems;
        }
        if (column != null && column is IGridDataColumn dataColumn) {
            foreach (var summaryType in SummaryTypes) {
                var fieldName = dataColumn.FieldName;
                if (IsStringColumn(fieldName) && summaryType != GridSummaryItemType.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(IGridDataColumn dataColumn, GridSummaryItemType 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 == GridSummaryItemType.Count ? null : dataColumn.DisplayFormat
                });
        StateHasChanged();
    }
}

WeatherForecast

using System;

public class WeatherForecast {
    public int ID { get; set; }
    public DateTime Date { get; set; }
    public int TemperatureC { get; set; }
    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
    public string? Summary { get; set; }
}

WeatherForecastService

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

public class WeatherForecastService {
    public readonly string[] Summaries = new[] {
        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
    };
    private List<WeatherForecast>? Forecasts;
    public Task<List<WeatherForecast>> GetForecastAsync() {
        if (Forecasts == null) {
            var rnd = new Random();
            Forecasts = Enumerable.Range(1, 50).Select(index => new WeatherForecast {
                ID = index,
                Date = DateTime.Today.AddDays(index),
                TemperatureC = rnd.Next(-20, 55),
                Summary = Summaries[rnd.Next(Summaries.Length)]
            }).ToList();
        }
        return Task.FromResult(Forecasts);
    }
    public Task<List<WeatherForecast>> ChangeForecastAsync(WeatherForecast changed) {
        var originalForecast = Forecasts.FirstOrDefault(i => i.ID == changed.ID);
        if (originalForecast != null) {
            originalForecast.TemperatureC = changed.TemperatureC;
            originalForecast.Summary = changed.Summary;
            originalForecast.Date = changed.Date;
        } else {
            Forecasts.Add(changed);
        }
        return Task.FromResult(Forecasts);
    }
    public Task<List<WeatherForecast>> Remove(WeatherForecast forecast) {
        Forecasts.Remove(forecast);
        return Task.FromResult(Forecasts);
    }
}

Program.cs

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

Run Demo: Context Menu

Implements

IGridCommandContext

ICommandContextBase

Inheritance

Object

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

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

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

GridGroupFooterCommandContext