[DefaultValue(GridContextMenus.None)]
[Parameter]
public GridContextMenus ContextMenus { get; set; }

@inject WeatherForecastService ForecastService

<DxGrid Data="@Data" ContextMenus="AvailableContextMenus">
    <Columns>
        <DxGridDataColumn FieldName="Date" DisplayFormat="D" />
        <DxGridDataColumn FieldName="TemperatureC" Caption="@("Temp. (\x2103)")" Width="120px" />
        <DxGridDataColumn FieldName="TemperatureF" Caption="@("Temp. (\x2109)")" Width="120px" />
        <DxGridDataColumn FieldName="Forecast" />
        <DxGridDataColumn FieldName="CloudCover" />
    </Columns>
</DxGrid>

@code {
    object Data { get; set; }
    GridContextMenus AvailableContextMenus;

    protected override void OnInitialized() {
        Data = ForecastService.GetForecast();
        // Activates all context menus (including menus without built-in items)
        AvailableContextMenus = GridContextMenus.All;
        // Disables all context menus
        AvailableContextMenus = GridContextMenus.None;
        // Activates only context menus that contain built-in items
        AvailableContextMenus = GridContextMenus.Header 
                                    | GridContextMenus.GroupPanel | GridContextMenus.GroupRow;
        // Activates menus for all elements except data rows
        AvailableContextMenus = GridContextMenus.All & ~GridContextMenus.DataRow;
    }
}

using System;

public class WeatherForecast {
    public DateTime Date { get; set; }
    public int TemperatureC { get; set; }
    public double TemperatureF => Math.Round((TemperatureC * 1.8 + 32), 2);
    public string Forecast { get; set; }
    public string CloudCover { get; set; }
    public bool Precipitation { get; set; }
}

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

public class WeatherForecastService {
private List<WeatherForecast> Forecast { get; set; }

private static string[] CloudCover = new[] {
    "Sunny", "Partly cloudy", "Cloudy", "Storm"
};

Tuple<int, string>[] ConditionsForForecast = new Tuple<int, string>[] {
    Tuple.Create( 22 , "Hot"),
    Tuple.Create( 13 , "Warm"),
    Tuple.Create( 0 , "Cold"),
    Tuple.Create( -10 , "Freezing")
};

public WeatherForecastService() {
    Forecast = CreateForecast();
}

private List<WeatherForecast> CreateForecast() {
    var rng = new Random();
    DateTime startDate = DateTime.Now;
    return Enumerable.Range(1, 15).Select(index => {
        var temperatureC = rng.Next(-10, 30);
        return new WeatherForecast {
            Date = startDate.AddDays(index),               
            TemperatureC = temperatureC,
            CloudCover = CloudCover[rng.Next(0, 4)],
            Precipitation = Convert.ToBoolean(rng.Next(0, 2)),
            Forecast = ConditionsForForecast.First(c => c.Item1 <= temperatureC).Item2
        };
    }).ToList();
}

public IEnumerable<WeatherForecast> GetForecast() {
    return Forecast.ToArray();
}
// ...
}

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

@inject NwindDataService NwindDataService

<DxGrid Data="Data"
        ShowGroupPanel="true"
        ContextMenus="@(GridContextMenus.Header)"
        CustomizeContextMenu="CustomizeContextMenu">
    <Columns>
        <DxGridSelectionColumn />
        <DxGridDataColumn FieldName="City" />
        <DxGridDataColumn FieldName="Country" />
        <DxGridDataColumn FieldName="CustomerName" GroupIndex="0" />
        <DxGridDataColumn FieldName="ProductName" />
        <DxGridDataColumn FieldName="Total"
                          UnboundType="GridUnboundColumnType.Decimal"
                          UnboundExpression="[UnitPrice] * [Quantity]"
                          DisplayFormat="c"
                          MinWidth="100" />
    </Columns>
</DxGrid>

@code {
    BindingList<Invoice> Data { get; set; }

    void CustomizeContextMenu(GridCustomizeContextMenuEventArgs args) {
        if (args.Context is GridHeaderCommandContext headerContext) {
            // Customizes context menu commands for the Total column header
            if (headerContext.Column is IGridDataColumn dataColumn && dataColumn.FieldName == "Total") {
                args.Items.Remove(GridContextMenuDefaultItemNames.GroupByColumn);
                args.Items.Remove(GridContextMenuDefaultItemNames.UngroupColumn);
            }
            // Customizes context menu commands for the selection column header
            if (headerContext.Column is IGridSelectionColumn selectionColumn) {
                var isFixed = selectionColumn.FixedPosition != GridColumnFixedPosition.None;
                string itemText = isFixed ? "Unfix Column" : "Fix Column to the Left";
                var newValue = isFixed ? GridColumnFixedPosition.None : GridColumnFixedPosition.Left;

                args.Items.AddCustomItem(itemText, () => {
                    headerContext.Grid.BeginUpdate();
                    headerContext.Column.FixedPosition = newValue;
                    headerContext.Grid.EndUpdate();
                });
            }
        }
    }

    protected override async Task OnInitializedAsync() {
        var invoices = await NwindDataService.GetInvoicesAsync();
        Data = new BindingList<Invoice>(invoices.ToList());
    }
}

public class Invoice {
    public string ShipName { get; set; }
    public string ShipAddress { get; set; }
    public string ShipCity { get; set; }
    public string ShipRegion { get; set; }
    public string ShipPostalCode { get; set; }
    public string ShipCountry { get; set; }
    public string CustomerId { get; set; }
    public string CustomerName { get; set; }
    public string Address { get; set; }
    public string City { get; set; }
    public string Region { get; set; }
    public string PostalCode { get; set; }
    public string Country { get; set; }
    public string Salesperson { get; set; }
    public int OrderId { get; set; }
    public DateTime? OrderDate { get; set; }
    public DateTime? RequiredDate { get; set; }
    public DateTime? ShippedDate { get; set; }
    public string ShipperName { get; set; }
    public int ProductId { get; set; }
    public string ProductName { get; set; }
    public decimal UnitPrice { get; set; }
    public short Quantity { get; set; }
    public float Discount { get; set; }
    public decimal? ExtendedPrice { get; set; }
    public decimal? Freight { get; set; }
}

public partial class NwindDataService {
    public Task<IEnumerable<Product>> GetProductsAsync(CancellationToken ct = default) {
        // Return your data here
    }
}

services.AddScoped<NwindDataService>();