[Flags]
public enum GridContextMenus

@inject WeatherForecastService ForecastService

<DxGrid Data="@Data" ContextMenu="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>();