How to cancel change in textbox?

[bstrother1]

What is the best way to cancel input in a Uno textbox with x:Bind before it reaches the backend of a two way binding so that it reverts to prior value?

[jeromelaban]

You can generally hook onto the UIElement.LosingFocus event and modify the Text property at that time, as by default a binding on TextBox.Text uses UpdateSourceTrigger=LostFocus.

That being said, if you're looking for validation you can use packages like those https://github.com/MADE-Apps/MADE.NET-UI, which provide a validator.

[jeromelaban]

Where did you find this feature? Is it something you used in WPF ?

[bstrother1]

https://docs.microsoft.com/en-us/dotnet/api/system.windows.dependencyproperty.unsetvalue?view=windowsdesktop-6.0

[jeromelaban]

Ok. Did you try with WinUI on Windows? It may be that this specific behavior is not supported.

[bstrother1]

It should also be supported by UWP and WPF https://docs.microsoft.com/en-us/uwp/api/windows.ui.xaml.dependencyproperty.unsetvalue?view=winrt-22621 this is hosted under UWP documentation and I found this tom-englert/TomsToolbox#4 which is a WPF package that mentions this.

[jeromelaban]

Can you make a sample that shows it working?