How to add or remove one TreeViewItem from its parent TreeViewItem?

[stackdamage]

I am trying to manully add or remove a TreeViewItem from its parent TreeViewItem. In WPF, I can do such operation with following codes.

       // Get a TreeViewItem
        TreeViewItem parentTI = GetParentTI();
        
        // Append a new child TreeViewItem 
        var aSubTi = new TreeViewItem() { Header = "Sub Child #1" };
        parentTI.Items.Add(aSubTi);

        // Remove a existing child TreeViewItem
        parentTI.Items.Remove(aSubTi);

However, I tried many methods in Avalonia 11, still cannot find a right way to successfuly implement such operation. Sometimes it throws exception which says 'System.InvalidOperationException: The control already has a visual parent.'. Is there any path to solve the problem? This question took me a long time. Thanks in advanced if anyone can give any tips.

[timunie]

Thanks in advanced if anyone can give any tips.

Better to use the MVVM pattern and use a TreeDataTemplate, see: https://docs.avaloniaui.net/docs/reference/controls/detailed-reference/treeview-1#example

[stackdamage]

Thanks for your reply. The operation senario is when user right click one of the TreeViewItem, a context menu is shown. Then user click Insert menu, and it's desired to append a new TreeViewItem behid the selected TreeViewItem. It would be better if the new inserted TreeViewItem can be selected after the insert operation is done. I am not sure if the MVVM pattern can implement such operation. I am still doing research on this.

[workgroupengineering]

TreeViewSample.zip

[stackdamage]

I tested your codes. It does work in MVVM pattern. I will learn from the sample and make changes in my project. Thank you @workgroupengineering