@page "/test"
@using System.Collections.ObjectModel

<TelerikToolBar Class="toolbar-size" Adaptive="false">    
    <ToolBarButton Icon="@SvgIcon.FileAdd" OnClick="@OnAdd">Add</ToolBarButton>
</TelerikToolBar>

<TelerikSplitter Height="500px">
    <SplitterPanes>
        <SplitterPane Size="20%" Collapsible="true">
            <TelerikTreeView Data="@Items" @bind-CheckedItems="@CheckedItems"                             
                             CheckBoxMode="TreeViewCheckBoxMode.Multiple">
                <TreeViewBindings>
                    <TreeViewBinding ParentIdField="ParentIdValue"></TreeViewBinding>
                </TreeViewBindings>
            </TelerikTreeView>
        </SplitterPane>
        <SplitterPane Collapsible="true">
        </SplitterPane>
    </SplitterPanes>
</TelerikSplitter>

@code {

    public class TreeItem
    {
        public int Id { get; set; }
        public string Text { get; set; }
        public int? ParentIdValue { get; set; }
        public bool HasChildren { get; set; }
        public ISvgIcon Icon { get; set; }
    }

    public ObservableCollection<TreeItem> Items { get; set; } = new ObservableCollection<TreeItem>();
    public IEnumerable<object> CheckedItems { get; set; } = new List<object>();

    private int counter;

    private void OnAdd()
    {
        this.Items.Add(new TreeItem { Id = counter, Text = $"test {counter}" });
        counter++;
    }
}

<QuickGrid Items="@_Items" ItemKey="(item) => item.Guid" Theme="">

https://docs.telerik.com/blazor-ui/components/grid/export/excel#basics


<TelerikGrid Data="@GridData" Pageable="true" Sortable="true" Resizable="true" Reorderable="true"
             FilterMode="@GridFilterMode.FilterRow" Groupable="true" >

    <GridToolBarTemplate>
        <GridCommandButton Command="ExcelExport" Icon="@SvgIcon.FileExcel">Export to Excel</GridCommandButton>
        <label class="k-checkbox-label"><TelerikCheckBox @bind-Value="@ExportAllPages" />Export All Pages</label>
    </GridToolBarTemplate>

    <GridExport>
        <GridExcelExport FileName="telerik-grid-export" AllPages="@ExportAllPages" />
    </GridExport>

    <GridColumns>
        Columns..
    </GridColumns>
</TelerikGrid>

@typeparam TEntity where TEntity : class, IEntity, new()

<div>
    <TelerikGrid 
        @ref="GridRef"
        Pageable="true"
        Sortable="true"
        Resizable="true"
        ShowColumnMenu="true"
        Reorderable="true"
        PageSize="50"
        SelectionMode="@GridSelectionMode.Single"
        SelectedItems="@_selectedItems"
        SelectedItemsChanged="@((IEnumerable<TEntity> list) => OnGridSelectedItemsChanged(list))"
        OnRowClick="@OnGridRowClick"
        OnRead="GetGridData"
        EnableLoaderContainer="true">
        @* toolbar, columns, etc. *@
    </TelerikGrid>

    <EditForm EditContext="@_editContext" OnSubmit="OnSubmitAsync">

        <TelerikDateTimePicker Placeholder=" "
            Value="(DateTime?)PropertyValue"
            ValueExpression="ValueExpression<DateTime?>()"
            ValueChanged="(DateTime? val) => OnValueChanged(val)"
            Readonly="true">
        </TelerikDateTimePicker>

    </EditForm>
</div>

@code {
    private EditContext? _editContext;
    private IEnumerable<TEntity> _selectedItems = Enumerable.Empty<TEntity>();
    private TEntity? _selectedItem;    

    [CascadingParameter] public TEntity? Entity { get; set; }

    protected override void OnInitialized()
    {
        _editContext = new(Entity);
        _editContext.OnFieldChanged += OnFieldChanged!;
    }

    // Override the grid's built-in row selection by handling the SelectedItemsChanged event. Do not execute any logic in it to let the OnGridRowClick handle the selection.
    // https://docs.telerik.com/blazor-ui/knowledge-base/grid-select-or-deselect-item-on-row-click
    private void OnGridSelectedItemsChanged(IEnumerable<TEntity> selectedList)
    {
    }

    private async Task OnGridRowClick(GridRowClickEventArgs args)
    {
        var currItem = args.Item as TEntity;

        if (currItem?.Id == _selectedItem?.Id) return;

        var discardChanges = await ConfirmDiscardFormChangesAsync();

        if (!discardChanges) return;

        _selectedItems = new[] { currItem };
        _selectedItem = _selectedItems.First();  
    }

    private async Task OnValueChanged(object? value)
    {
        // not getting fired when grid's selected item is changed, which is good
    }

    private void OnFieldChanged(object sender, FieldChangedEventArgs args)
    {
        // gets fired when grid's selected item is changed
        // _editContext.IsModified() is true here
    }
}