GridFooterCommandContext.SummaryItems Property

Returns total summaries contained in the target cell.

Namespace: DevExpress.Blazor

Assembly: DevExpress.Blazor.v25.2.dll

Declaration

public IReadOnlyList<IGridSummaryItem> SummaryItems { get; }

Property Value

Type	Description
IReadOnlyList<IGridSummaryItem>	A total summary collection.

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. 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.

When the target element is a footer cell, the Context property returns a GridFooterCommandContext object. Use the object’s SummaryItems property to access total summaries contained in the target cell.

Example

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

Razor

@inject WeatherForecastService ForecastService

<DxGrid Data="@forecasts"
        PageSize="5" 
        FooterDisplayMode="GridFooterDisplayMode.Always"
        ContextMenus="GridContextMenus.Footer"
        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" />
        <DxGridDataColumn FieldName=@nameof(WeatherForecast.Date) DisplayFormat="dd/MM/yyyy" />
    </Columns>
    <TotalSummary>
        @foreach (var item in SummaryItems) {
            <DxGridSummaryItem FieldName="@item.FieldName"
                               SummaryType="item.Type"
                               ValueDisplayFormat="@item.DisplayFormat"
                               @key="item" />
        }
    </TotalSummary>
</DxGrid>

@code {
    string[]? summaries;
    private List<WeatherForecast>? forecasts;

    IList<SummaryItem> SummaryItems { 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;
        SummaryItems = 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 GridFooterCommandContext footerCommandContext) {
            column = footerCommandContext.Column;
            contextSummaryItems = footerCommandContext.SummaryItems;
            summaryItemsCollection = SummaryItems;
        }
        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