How do I update the view after not changing the viewmodel binding source?

[Justin113D]

I have a TextBox with a Mode=TwoWay binding to a ViewModel and UpdateSourceTrigger=LostFocus. In the ViewModel, whitespace gets trimmed on setting, something like this:

        private string _text = string.Empty;

        public string Text
        {
            get => _text;
            set
            {
                _text = value.Trim();
                PropertyChanged?.Invoke(this, new(nameof(Text)));
            }
        }

In other words, upon losing focus, i want the TextBox to update and remove all whitespace at the start and end. The issue is that, when the only thing i do is add whitespace, the value behind the binding does not change, and so the text in the UI does not change either, meaning the whitespace remains.

I have no idea how to properly make it update and have it remove the whitespace after adding whitespace, but i did find a reliable workaround:

private string _workaroundText = string.Empty;

public string WorkaroundText
{
    get => _workaroundText;
    set
    {
        string previousValue = _workaroundText;
        _workaroundText = value.Trim();
        PropertyChanged?.Invoke(this, new(nameof(WorkaroundText)));

        if(previousValue == _workaroundText && value != _workaroundText)
        {
            string newValue = _workaroundText;
            _workaroundText += ' ';
            PropertyChanged?.Invoke(this, new(nameof(WorkaroundText)));
            _workaroundText = newValue;
            PropertyChanged?.Invoke(this, new(nameof(WorkaroundText)));
        }
    }
}

Essentially, i do make a change, tell the ui to update with it, change it back, and tell the UI to update again. This works, but is ugly. Is there a better solution?

Workaround in action: