@using System.Collections.ObjectModel

<TelerikButton OnClick="@AddChildClick">Add Child</TelerikButton>

@if (TreeViewVisible)
{
    <TelerikTreeView Data="@ProductTypesFlatData">
        <TreeViewBindings>
            <TreeViewBinding ParentIdField="ParentIdValue" ExpandedField="Expanded"></TreeViewBinding>
        </TreeViewBindings>
    </TelerikTreeView>
}

@code{
    bool TreeViewVisible { get; set; } = true;
    async Task RepaintTree()
    {
        TreeViewVisible = false;
        await Task.Delay(30);
        TreeViewVisible = true;
        StateHasChanged();
    }

    private ObservableCollection<TreeItem> ProductTypesFlatData { get; set; }

    private int _childCounter = 1;

    protected override void OnInitialized()
    {
        ProductTypesFlatData = new ObservableCollection<TreeItem>();
        ProductTypesFlatData.Add(new TreeItem() { Expanded = true, HasChildren = true, Icon = IconName.Folder, Id = "1", ParentIdValue = null, Text = "Parent1" });
        AddChild();
        AddChild();
        AddChild();
    }

    private async Task AddChildClick()
    {
        AddChild();
        await RepaintTree();
    }

    private void AddChild()
    {
        ProductTypesFlatData.Add(new TreeItem() { Expanded = false, HasChildren = false, Icon = IconName.Gear, Id = $"1.{_childCounter.ToString()}", ParentIdValue = "1", Text = $"Child{_childCounter}" });
        _childCounter++;
    }

    public class TreeItem
    {
        public string Id { get; set; }
        public string Text { get; set; }
        public string ParentIdValue { get; set; }
        public bool HasChildren { get; set; }
        public string Icon { get; set; }
        public bool Expanded { get; set; }
    }
}