MVVM Tabcontrol change tab

Question

I am developing an mvvm app with wpf. A requirement just got added on to block the user from changing tabs if a textbox has text.

What is the best way to do this completely in the viewmodel? I don't know how to block a tabitem because there is no dependencyobject command in the tabcontrol to tie into, do i need to roll my own tabcontrol and build an ICommand around the SelectionChanged event?

Should I simply (eegad..don't say it) put code in the code behind of the view in the SelectionChanged event?

Do I have an alternative that I haven't thought of?

Answer 1

You might consider binding each of the TabItems' IsEnabled property to a property in your ViewModel (e.g. ViewModel.TabsEnabled) and set that property to False when the textbox has text. That way, you'll be able to enable/disable those tabs from your ViewModel without having to have a code behind file for that particular view.

Which means you'll have something like the following in your view (assuming your ViewModel is a static class named ViewModel):

<TabItem IsEnabled="{Binding Source={x:Static local:ViewModel.TabsEnabled}}"/>

Then you just have to set the TabsEnabled property on the ViewModel when one of the textboxes has content; there are a couple of ways to do this, but if they are bound to your ViewModel you should have plenty of opportunities to listen for changes and set TabsEnabled as appropriate.