@using Telerik.DataSource
@using Telerik.DataSource.Extensions
@using System.IO

<TelerikGrid TItem="@object"
             LoadGroupsOnDemand="true"
             Groupable="true"
             OnStateInit="@((GridStateEventArgs<object> args) => OnStateInitHandler(args))"
             OnRead="@ReadItems"
             ScrollMode="@GridScrollMode.Virtual" PageSize="20" RowHeight="60"
             Navigable="true" Sortable="true" FilterMode="@GridFilterMode.FilterRow" Height="600px">
    <GridColumns>
        <GridColumn Field="@nameof(Employee.Name)" FieldType="@typeof(string)" Groupable="false" />
        <GridColumn Field="@nameof(Employee.Team)" FieldType="@typeof(string)" Title="Team" />
        <GridColumn Field="@nameof(Employee.Salary)" FieldType="@typeof(decimal)" Groupable="false" />
        <GridColumn Field="@nameof(Employee.IsOnLeave)" FieldType="@typeof(bool)" Title="On Vacation" />
    </GridColumns>
</TelerikGrid>

@code {
    List<object> GridData { get; set; }

    protected async Task ReadItems(GridReadEventArgs args)
    {
        DataEnvelope<Employee> result = await MyService.GetData(args.Request);

        if (args.Request.Groups.Count > 0)
        {
            args.Data = result.GroupedData.Cast<AggregateFunctionsGroup>().ToList();
        }
        else
        {
            args.Data = result.CurrentPageData.Cast<Employee>().ToList();
        }

        args.Total = result.TotalItemCount;

        if (args.Request.Groups.Count > 0)
        {
            try
            {
                List<AggregateFunctionsGroup> items = result.GroupedData.Cast<AggregateFunctionsGroup>().ToList();

                await using var s = new MemoryStream();
                await System.Text.Json.JsonSerializer.SerializeAsync(s, items);
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
            }
        }
    }

    void OnStateInitHandler(GridStateEventArgs<object> args)
    {
        // set initial grouping
        GridState<object> desiredState = new GridState<object>()
        {
            GroupDescriptors = new List<GroupDescriptor>()
    {
                new GroupDescriptor()
                {
                    Member = "Team",
                    MemberType = typeof(string)
                },
                new GroupDescriptor()
                {
                    Member = "IsOnLeave",
                    MemberType = typeof(bool)
                }
            }
        };

        args.GridState = desiredState;
    }

    public class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
        public string Team { get; set; }
        public bool IsOnLeave { get; set; }
        public decimal Salary { get; set; }
    }

    public class DataEnvelope<T>
    {
        public List<AggregateFunctionsGroup> GroupedData { get; set; }
        public List<T> CurrentPageData { get; set; }
        public int TotalItemCount { get; set; }
    }

    public static class MyService
    {
        private static List<Employee> SourceData { get; set; }
        public static async Task<DataEnvelope<Employee>> GetData(DataSourceRequest request)
        {
            if (SourceData == null)
            {
                SourceData = new List<Employee>();
                var rand = new Random();
                for (int i = 1; i <= 2500; i++)
                {
                    SourceData.Add(new Employee()
                    {
                        EmployeeId = i,
                        Name = "Employee " + i.ToString(),
                        Team = "Team " + i % 100,
                        IsOnLeave = i % 3 == 0,
                        Salary = rand.Next(1000, 5000)
                    });
                }
            }

            await Task.Delay(500);// deliberate delay to showcase async operations, remove in a real app

            // retrieve data as needed, you can find more examples and runnable projects here
            // https://github.com/telerik/blazor-ui/tree/master/grid/datasourcerequest-on-server
            var datasourceResult = SourceData.ToDataSourceResult(request);

            DataEnvelope<Employee> dataToReturn;

            if (request.Groups.Count > 0)
            {
                dataToReturn = new DataEnvelope<Employee>
                {
                    GroupedData = datasourceResult.Data.Cast<AggregateFunctionsGroup>().ToList(),
                    TotalItemCount = datasourceResult.Total
                };
            }
            else
            {
                dataToReturn = new DataEnvelope<Employee>
                {
                    CurrentPageData = datasourceResult.Data.Cast<Employee>().ToList(),
                    TotalItemCount = datasourceResult.Total
                };
            }

            return await Task.FromResult(dataToReturn);
        }
    }
}

 <GridSettings>
        <GridPopupEditFormSettings ButtonsLayout="FormButtonsLayout.Center"/>
 </GridSettings>

@using System.Net.Http.Json
@using System.Text.RegularExpressions
@using Telerik.Blazor.Extensions
@using WasmApp.Shared
@inject HttpClient Http

<TelerikGrid Data=@GridData
             Height="460px"
             RowHeight="60"
             PageSize="10"
             Pageable="true"
             Sortable="true"
             FilterMode="@GridFilterMode.FilterRow"
             SortMode="@SortMode.Multiple"
             OnRead=@ReadItems
             TotalCount=@Total>
    <GridColumns>
        <GridColumn Field="ProductID" />
        <GridColumn Field="ProductName" />
        <GridColumn Field="Discontinued" />
    </GridColumns>
</TelerikGrid>

@code{
    public List<ODataProduct> GridData { get; set; } = new List<ODataProduct>();
    public int Total { get; set; } = 0;

    protected async Task ReadItems(GridReadEventArgs args)
    {
        var baseUrl = "https://demos.telerik.com/kendo-ui/service-v4/odata/Products?";

        string OdataUrl = args.Request.ToODataString();

        // replace the original orederby clause with one that contains all the order rules
        Regex x = new Regex("(orderby=)(.*?)(&)", RegexOptions.IgnoreCase);
        string actualOrderByClause = "orderby=";

        for (int i = 0; i < args.Request.Sorts.Count; i++)
        {
            if (i > 0)
            {
                actualOrderByClause += ",";
            }
            string order = args.Request.Sorts[i].SortDirection == Telerik.DataSource.ListSortDirection.Ascending ? "" : "%20desc";
            actualOrderByClause += $"{args.Request.Sorts[i].Member}{order}";
        }

        actualOrderByClause += "&";

        string OdataQueryWithMultipleOrder = x.Replace(OdataUrl, actualOrderByClause);

        //do the request as usual
        var requestUrl = $"{baseUrl}{OdataQueryWithMultipleOrder}";

        ODataResponseOrders response = await Http.GetFromJsonAsync<ODataResponseOrders>(requestUrl);

        GridData = response.Products;
        Total = response.Total;
    }
}

CS1729: GridExcelExportColumn does not contain a constructor that takes 0 arguments.