WPF Event Binding to ViewModel (for non-Command classes)

c# xaml mvvm binding viewmodel
RobotNerd picture RobotNerd · Jun 21, 2011 · Viewed 38.7k times · Source

I'm working an the second version of an application, and as part of the rewrite I have to move to an MVVM architecture. I'm getting pressure to put absolutely every bit of code in the view model class--having c# in the code behind file is frowned upon. (I know, I know...I understand that code behind isn't a bad thing, but it isn't my call this time).

For objects which implement the command interface, it's easy. I've been able to find a ton of information on how to bind the Command of these objects to an ICommand in the view model. The problem is for objects which don't have this interface, e.g.

<ListBox
   x:Name="myListBox"
   MouseDoubleClick="myCallbackFunction">

<!-- ... -->

</ListBox>

I want to know how to bind the MouseDoubleClick event for the Listbox to myCallbackFunction, which is implemented in the view model. Is this even possible?

Thanks!

Answer

Reed Copsey picture Reed Copsey · Jun 21, 2011

This isn't directly possible. It could be done via an Attached Property or Behavior, though it would still be a little tricky to find and invoke the appropriate method (this could be done via Reflection fairly easily).

That being said, this is typically handled via ICommand - For example, MVVM Light has a great EventToCommand behavior to map any event to an ICommand on the ViewModel. The advantage of using ICommand is that you can still use DataBinding, since the ICommand is exposed as a property.

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