@using Telerik.Blazor
@using Telerik.Blazor.Components.Grid

<TelerikGrid Data=@GridData
             SelectionMode="GridSelectionMode.Multiple"
             @bind-SelectedItems="SelectedItems"
             Pageable="true"
             Height="400px">
    <TelerikGridToolBar>
        <TelerikGridCommandButton Command="MyDelete" OnClick="DeleteSelectedAsync"
                                         Enabled=@(SelectedItems?.Count() > 0) Icon="delete">Delete</TelerikGridCommandButton>
        <TelerikGridCommandButton Enabled="false" OnClick="DeleteSelectedAsync">I must always be disabled</TelerikGridCommandButton>
</TelerikGridToolBar>
    <TelerikGridColumns>
        <TelerikGridCheckboxColumn />
        <TelerikGridColumn Field=@nameof(Employee.Name) />
        <TelerikGridColumn Field=@nameof(Employee.Team) Title="Team" />
    </TelerikGridColumns>
</TelerikGrid>

@result

@if (SelectedItems != null)
{
    <ul>
        @foreach (Employee employee in SelectedItems)
        {
            <li>
                @employee.Name
            </li>
        }
    </ul>
}

@code {
    void DeleteSelectedAsync()
    {
        result = $"On {DateTime.Now} there are {SelectedItems?.Count()} items selected";
    }
    string result;

    public List<Employee> GridData { get; set; }
    public IEnumerable<Employee> SelectedItems { get; set; }

    protected override void OnInitialized()
    {
        GridData = new List<Employee>();
        for (int i = 0; i < 15; i++)
        {
            GridData.Add(new Employee()
            {
                EmployeeId = i,
                Name = "Employee " + i.ToString(),
                Team = "Team " + i % 3
            });
        }

        // select Employee with 3 through 5
        SelectedItems = GridData.Skip(2).Take(3).ToList();
    }

    public class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
        public string Team { get; set; }
    }
}

<TelerikGrid Data="salesTeamMembers" PageSize="4" Pageable="true" @bind-SelectedItems="@SelectedItemsMainGrid" SelectionMode="@GridSelectionMode.Single">
    <DetailTemplate>
        @{
            var employee = context as MainModel;
            <TelerikGrid Data="employee.Orders" Pageable="true" PageSize="7" SelectionMode="@GridSelectionMode.None">
                <GridColumns>
                    <GridColumn Field="OrderId"></GridColumn>
                    <GridColumn Field="DealSize"></GridColumn>
                </GridColumns>
            </TelerikGrid>
        }
    </DetailTemplate>
    <GridColumns>
        <GridColumn Field="Id"></GridColumn>
        <GridColumn Field="Name"></GridColumn>
    </GridColumns>
</TelerikGrid>

@foreach (var item in SelectedItemsMainGrid)
{
    <div>@item.Name</div>
}

@code {
    List<MainModel> salesTeamMembers { get; set; }
    public IEnumerable<MainModel> SelectedItemsMainGrid { get; set; } = Enumerable.Empty<MainModel>();

    protected override void OnInitialized()
    {
        salesTeamMembers = GenerateData();
    }

    private List<MainModel> GenerateData()
    {
        List<MainModel> data = new List<MainModel>();
        for (int i = 1; i < 16; i++)
        {
            MainModel mdl = new MainModel { Id = i, Name = $"Name {i}" };
            mdl.Orders = Enumerable.Range(1, 15).Select(x => new DetailsModel { OrderId = x, DealSize = x ^ i }).ToList();
            data.Add(mdl);
        }
        return data;
    }

    public class MainModel
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public List<DetailsModel> Orders { get; set; }
    }

    public class DetailsModel
    {
        public int OrderId { get; set; }
        public double DealSize { get; set; }
    }
}