@using Telerik.DataSource

<p>Group by a third column, so that it should come last in the Group Panel:</p>

<TelerikGrid @ref="@GridRef"
             Data="@GridData"
             Pageable="true"
             Sortable="true"
             Groupable="true"
             FilterMode="GridFilterMode.FilterRow"
             OnStateInit="@( (GridStateEventArgs<Employee> args) => OnGridStateInit(args) )"
             OnStateChanged="@( (GridStateEventArgs<Employee> args) => OnGridStateChanged(args) )">
    <GridColumns>
        <GridColumn Field="@nameof(Employee.Name)" />
        <GridColumn Field="@nameof(Employee.Team)" />
        <GridColumn Field="@nameof(Employee.Salary)" />
        <GridColumn Field="@nameof(Employee.OnVacation)" />
    </GridColumns>
</TelerikGrid>

@code {
    private TelerikGrid<Employee>? GridRef { get; set; }

    private List<Employee> GridData { get; set; } = new();

    private void OnGridStateInit(GridStateEventArgs<Employee> args)
    {
        args.GridState.GroupDescriptors = new List<GroupDescriptor>();

        args.GridState.GroupDescriptors.Add(new GroupDescriptor()
        {
            Member = nameof(Employee.Team),
            MemberType = typeof(string)
        });

        args.GridState.GroupDescriptors.Add(new GroupDescriptor()
        {
            Member = nameof(Employee.OnVacation),
            MemberType = typeof(bool)
        });
    }

    private async Task OnGridStateChanged(GridStateEventArgs<Employee> args)
    {
        if (args.PropertyName == "GroupDescriptors" && args.GridState.GroupDescriptors.Count > 2 && GridRef != null)
        {
            var secondGroupDescriptor = args.GridState.GroupDescriptors.ElementAt(1);

            args.GridState.GroupDescriptors.Remove(secondGroupDescriptor);
            args.GridState.GroupDescriptors.Add(secondGroupDescriptor);

            await GridRef.SetStateAsync(args.GridState);
        }
    }

    protected override void OnInitialized()
    {
        var rnd = new Random();

        for (int i = 1; i <= 20; i++)
        {
            GridData.Add(new Employee()
            {
                Id = i,
                Name = "Name " + i,
                Team = "Team " + (i % 4 + 1),
                Salary = (decimal)rnd.Next(1000, 3000),
                OnVacation = i % 3 == 0
            });
        }
    }

    public class Employee
    {
        public int Id { get; set; }
        public string Name { get; set; } = string.Empty;
        public string Team { get; set; } = string.Empty;
        public decimal Salary { get; set; }
        public bool OnVacation { get; set; }
    }
}

@using System.Collections.Generic;
@using System.Dynamic;
    <span>Selection bind not working as expected:</span>
    <TelerikGrid TItem="ExpandoObject"
    @bind-SelectedItems="@gSelectedItems"
                 OnRowClick="@OnGridRowClicked"
                 SelectionMode="GridSelectionMode.Multiple"
                 OnRead=@gHLReadItems
                 RowHeight="60">
        <RowTemplate Context="ctx">
            <td>
                @{
                    var it = (ctx as IDictionary<string, object>);
                    @(it["Name"].ToString())
                }
            </td>
        </RowTemplate>
        <GridColumns>
            <GridCheckboxColumn CheckBoxOnlySelection="true" Visible="false" @key="@("sIDX1")" SelectAll="false" />
            <GridColumn Field="Name" FieldType=@typeof(string) Title="Name" />
        </GridColumns>
    </TelerikGrid>
<span>WORKs OK:</span>
    <TelerikGrid TItem="ExpandoObject"
    @bind-SelectedItems="@gSelectedItems"
                 OnRowClick="@OnGridRowClicked"
                 SelectionMode="GridSelectionMode.Multiple"
                 OnRead=@gHLReadItems
                 RowHeight="60">
        <GridColumns>
            <GridCheckboxColumn CheckBoxOnlySelection="true" Visible="false" @key="@("sIDX2")" SelectAll="false" />
            <GridColumn Field="Name" FieldType=@typeof(string) Title="Name" />
        </GridColumns>
    </TelerikGrid>
        
@code
{
    private List<ExpandoObject> RowData;
    IEnumerable<ExpandoObject> gSelectedItems { get; set; } = Enumerable.Empty<ExpandoObject>();
    protected override void OnInitialized()
    {
        
        RowData = new List<ExpandoObject>();
        dynamic obj0 = new ExpandoObject();
        obj0.Name = "Tester";
        RowData.Add(obj0);
        dynamic obj1 = new ExpandoObject();
        obj1.Name = "Testovicz";
        RowData.Add(obj1);
        dynamic obj2 = new ExpandoObject();
        obj2.Name = "Selectant";
        RowData.Add(obj2);
    }
    protected async Task gHLReadItems(GridReadEventArgs args)
    {
        //RowData are readen from DYNAMIC source, cannot add any NEW property to it
        args.Data = RowData;
        args.Total = 3;
    }
    protected void OnGridRowClicked(GridRowClickEventArgs args)
    {
        var it = args.Item as ExpandoObject;
        if (gSelectedItems.Any(x => x == it))
        {
            gSelectedItems = gSelectedItems.Where(x => x != it);
        }
        else
        {
            gSelectedItems = gSelectedItems.Union(RowData.Where(x => x == it));
        }
    }
}

<TelerikRootComponent>
    <TelerikGrid Data="@GridData"
                 Height="350px"
                 Sortable="true"
                 Pageable="true"
                 SortMode="@SortMode.Single"
                 FilterMode="@GridFilterMode.FilterMenu"
                 FilterMenuType="@FilterMenuType.CheckBoxList"
                 PageSize="10">
        <GridColumns>
            <GridColumn Field="Col1" Width="80px" Locked="true" />
            <GridColumn Field="Col2" Width="140px" />
        </GridColumns>
    </TelerikGrid>
</TelerikRootComponent>

@code { public List<dynamic> GridData = new List<dynamic>();

    protected async override Task OnInitializedAsync()
    {
        for (int i = 1; i < 10; i++)
        {
            dynamic row = new ExpandoObject();
            row.Col1 = $"col1_{i}";
            row.Col2 = $"col2_{i}";
            GridData.Add(row);
        }

    } }

<TelerikGrid Data=@sysVars.Dtos Pageable="true" Sortable="true" FilterMode="Telerik.Blazor.GridFilterMode.FilterRow" PageSize="20" TotalCount=@sysVars.Count OnRead=@ReadItems>
        <GridColumns>
            <GridColumn Field=@nameof(SysVar.SysVarType.Name) Title="Type" Editable="false">
                <Template>
                    @{
                        var data = context as SysVar;
                        @data.SysVarType.Name
                    }
                </Template>
            </GridColumn>
            <GridColumn Field=@nameof(SysVar.Value) Title="Value">
                <Template>
                    @{
                        var data = context as SysVar;
                        var link = SysVarDto.FrontEndEditUrl(data.Id.Value);
                        <NavLink href=@link>@data.Value</NavLink>
                    }
                </Template>
            </GridColumn>
            <GridColumn Field=@nameof(SysVar.Hierarchy.Description) Title="Hierarchy">
                <Template>
                    @{
                        var data = context as SysVar;
                        @data.Hierarchy.Description
                    }
                </Template>
            </GridColumn>
        </GridColumns>
    </TelerikGrid>

 public class SysVar 
    {
        public string Value { get; set; }

        public Hierarchy Hierarchy { get; set; }

        public SysVarType SysVarType { get; set; }
}

public class Hierarchy 
{
      public string Description { get; set; }
}

public class SysVarType
{
      public string Name { get; set; }
}

https://localhost:44335/odata/v1/SysVarOData?$count=true&$expand=sysVarType($select=name),hierarchy($select=description)&$skip=0&$top=20&$orderby=value,sysVarType/name

https://localhost:44335/odata/v1/SysVarOData?$count=true&$expand=sysVarType($select=name),hierarchy($select=description)&$skip=0&top=20&$orderby=Name

System.NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.Blazor.Components.TelerikGridBase`1.FocusPagerAsync()
   at Telerik.Blazor.Components.TelerikGridBase`1.FocusCellAsync(GridNavigationCommandEventArgs args)
   at Telerik.Blazor.Components.TelerikGridBase`1.FocusAdjacentCellAsync(GridNavigationCommandEventArgs args, Int32 rowIndexOffset, Int32 columnIndexOffset)
   at Telerik.Blazor.Components.TelerikGridBase`1.FocusBottomCellAsync(GridNavigationCommandEventArgs args)
   at Telerik.Blazor.Components.TelerikGridBase`1.ExecuteNavigationCommandAsync(GridNavigationCommandEventArgs args)
   at Telerik.Blazor.Components.TelerikGridBase`1.ExecuteCommand(Object args)
   at Telerik.Blazor.Components.Grid.GridRowBase`1.OnExecuteCommand(GridCommandEventArgs commandArgs)
   at Telerik.Blazor.Components.Grid.GridDataCellBase`1.ExecuteCommandAsync(GridCommandEventArgs args)
   at Telerik.Blazor.Components.Grid.GridNavigableCellBase`1.ExecuteNavigationCommandAsync(String commandName, Int32 rowIndexOffset, Int32 columnIndexOffset, KeyboardEventArgs args)
   at Telerik.Blazor.Components.Grid.GridNavigableCellBase`1.ProcessKeyDown(KeyboardEventArgs args)
   at Telerik.Blazor.Components.Grid.GridContentCell`1.ProcessKeyDown(KeyboardEventArgs args)
   at Telerik.Blazor.Components.Grid.GridNavigableCellBase`1.OnKeyDown(KeyboardEventArgs args)
   at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle)