@page "/"

<TelerikGrid Data=@GridData
             SelectionMode="GridSelectionMode.Multiple"
             SelectedItemsChanged="@((IEnumerable<Employee> employeeList) => OnSelect(employeeList))"
             SelectedItems="@PersistedSelectedItems"
             @bind-Page="@CurrentPage"
             PageSize="@PageSize"
             Pageable="true"
             FilterMode="GridFilterMode.FilterRow"
             OnStateChanged="@((GridStateEventArgs<Employee> args) => OnStateChangedHandler(args))">
    <GridColumns>
        <GridCheckboxColumn />
        <GridColumn Field=@nameof(Employee.EmployeeId) />
        <GridColumn Field=@nameof(Employee.Name) />
        <GridColumn Field=@nameof(Employee.Team) />
    </GridColumns>
</TelerikGrid>

@if (PersistedSelectedItems != null)
{
    <ul>
        @foreach (Employee employee in PersistedSelectedItems.OrderBy(e => e.EmployeeId))
        {
            <li>
                @employee.EmployeeId
            </li>
        }
    </ul>
}

@code {
    public List<Employee> PersistedSelectedItems { get; set; } = new List<Employee>();
    int CurrentPage { get; set; }
    int PageSize { get; set; } = 5;

    private async void OnStateChangedHandler(GridStateEventArgs<Employee> args)
    {
        await Task.Delay(5000);
    }

    protected void OnSelect(IEnumerable<Employee> employees)
    {
        IEnumerable<Employee> CurrentPageEmployees = GridData.Skip(PageSize * (CurrentPage - 1)).Take(PageSize);

        if (employees == null || employees.Count() == 0)
        {
            //the user de-selected all items with the header checkbox
            PersistedSelectedItems = PersistedSelectedItems.Except(CurrentPageEmployees).ToList();
        }
        else
        {
            //handle any deselected items
            var UnselectedEmployees = CurrentPageEmployees.Except(employees);
            PersistedSelectedItems = PersistedSelectedItems.Except(UnselectedEmployees).ToList();

            //add any new items if they were not selected already
            foreach (var item in employees)
            {
                if (!PersistedSelectedItems.Contains(item))
                {
                    PersistedSelectedItems.Add(item);
                }
            }
        }
    }

    //data binding and sample data
    public List<Employee> GridData { 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
            });
        }
    }

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

<TelerikGrid Data=@GridData Pageable="true" Height="300px">
    <GridColumns>
        <GridColumn Field="@(nameof(Employee.EmployeeId))">
            <FooterTemplate>
                some footer
            </FooterTemplate>
        </GridColumn>
        <GridColumn Field=@nameof(Employee.Salary) Title="Salary">
        </GridColumn>
        <GridColumn Field=@nameof(Employee.Name)>
        </GridColumn>
    </GridColumns>
</TelerikGrid>

@code {
    public List<Employee> GridData { get; set; } // = new List<Employee>(); // workaround

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

<TelerikGrid Data="@MyData" Height="300px" Pageable="true" Sortable="true" FilterMode="@GridFilterMode.FilterMenu" Reorderable="true">
    <GridColumns>
        <GridColumn Field="@(nameof(SampleData.ID))" Title="This title will not be rendered">
            <HeaderTemplate>
                Continent <br />
                <div style="text-align:center">Id</div>
                <div @onclick:stopPropagation="true" data-draggable="false">
                    <TelerikComboBox Data="@Continents" Filterable="true" class="headerCombo"
                                     @bind-Value="@SelectedContinentId"
                                     TextField="@nameof(Continent.Name)" ValueField="@nameof(Continent.Id)" Id="MyId">
                    </TelerikComboBox>
                </div>
            </HeaderTemplate>
        </GridColumn>
        <GridColumn Field=@nameof(SampleData.Name) Title="First Name" />
    </GridColumns>
</TelerikGrid>

@code {
    /* Grid */
    string result { get; set; }
    void DoSomething()
    {
        result = $"button in header template clicked on {DateTime.Now}, something happened";
    }

    public class SampleData
    {
        public int ID { get; set; }
        public string Name { get; set; }
        public DateTime HireDate { get; set; }
    }

    public IEnumerable<SampleData> MyData = Enumerable.Range(1, 50).Select(x => new SampleData
    {
        ID = x,
        Name = "name " + x,
        HireDate = DateTime.Now.AddDays(-x)
    });

    /* ComboBox */

    public class Continent
    {
        public int Id { get; set; }
        public string Name { get; set; }
    }
    IEnumerable<Continent> Continents = new List<Continent>() { new Continent { Id = 1, Name = "Africa" }, new Continent { Id = 2, Name = "Asia" }, new Continent { Id = 3, Name = "South America" } };
    public int SelectedContinentId { get; set; } = 1;

}