TextBox.TextChanged & ICommandSource

Question

I am following the M-V-VM pattern for my WPF UI. I would like to hook up a command to the TextChanged event of a TextBox to a command that is in my ViewModel class. The only

Answer 1

First off, you've surely considered two-way data binding to your viewmodel, with an UpdateSourceTrigger of PropertyChanged? That way the property setter of the property you bind to will be called every time the text is changed?

If that's not enough, then I would tackle this problem using Attached Behaviours. On Julian Dominguez’s Blog you'll find an article about how to do something very similar in Silverlight, which should be easily adaptable to WPF.

Basically, in a static class (called, say TextBoxBehaviours) you define an Attached Property called (perhaps) TextChangedCommand of type ICommand. Hook up an OnPropertyChanged handler for that property, and within the handler, check that the property is being set on a TextBox; if it is, add a handler to the TextChanged event on the textbox that will call the command specified in the property.

Then, assuming your viewmodel has been assigned to the DataContext of your View, you would use it like: