Losing Check State on rebind?

[Thomas]

I have the following page:

@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++;
    }
}

If I add some items with the add button, then check some items, and then add some more items, the check state seems to be lost.

However, if I collapse and expand the split panel, the items get checked again.

Is this a bug, or what am I doing wrong?

[Hristian Stefanov]

Hi Thomas,

A bug report has already been submitted on our public feedback portal that covers the described behavior: TreeView does not respect any overriden implementation of "Equals" on the model. I voted for it on your behalf and raised its priority.

You can also subscribe to receive email notifications for further status updates.

Regards,
Hristian Stefanov
Progress Telerik