Equivalent of PostMessage in C# to synchronize with the main thread with MVVM?

Question

I must be retarded with searching, because here\'s another seemingly common problem that I haven\'t been able to solve.

Here\'s my problem -- I am using WPF and MVVM

Answer 1

If you want to schedule some work from a background thread to the UI thread in WPF, use the DispatcherObject. Here's a nice article on how to Build More Responsive Apps with the Dispatcher.

Update: Note that if you use an event to send notifications from the Model to the ViewModel, you still need to switch to the UI thread somewhere. Whether that switch should be in the Model or the ViewModel is a good design discussion, but it's orthogonal to your question.

The event will be raised on the corresponding Dispatcher thread. Since you need to get to the UI thread, you need to use a Dispatcher that is created on the UI thread. The easiest way to get one is to use the DispatcherObject.Dispatcher property on one of the UI elements. The alternative is to create one in your Model or ViewModel. If you are a design purist, I would suggest you create the Dispatcher in your Model and dispatch the call back to the UI thread before you raise the event to which the ViewModel is listening. This way all the thread switching and management is contained in your Model and the ViewModel works as a single-threaded on the UI thread only.