如何在Caliburn.Micro中使用View的结果调用ViewModel方法

Question

In my Caliburn.Micro project I have a Window view.

I use some Invoke in the View to call methods of the ViewModel:

private void ViewEvent1(object sender, RoutedEventArgs e)
{
  Caliburn.Micro.Action.Invoke(DataContext, "Event1Occured");
}

private void ViewEvent2(object sender, RoutedEventArgs e)
{
  Caliburn.Micro.Action.Invoke(DataContext, "Event2Occured");
}

They work just fine.

In my View, I have a method that closes the Window:

private void EventClose(object sender, RoutedEventArgs e)
{
  this.DialogResult = false;      
  Close();
}

Unfortunately I have to check some conditions in the ViewModel before the closing takes effect.

The problem is that Invoke return void , so I cannot call a method that returns a value.

Is there an alternative for Invoke to get the result from the ViewModel's method?

Answer 1

You don't want to be doing your method calls to viewmodels from the view in that nature.. kinda breaks the ideas behind CMs abilities even for the items that you claim work.

as eran otzap pointed out you need use convention or Message.Attach, to call a method on the viewmodel from the view is breaking a few things, might as well not use CM in this case. Some will go as far as deleting code behind files altogether, because they don't use them at all.

Secondly, if it's view related then it doesn't affect the viewmodel that is ok, but since you are calling the viewmodel the premise of SoC and MVVM are thrown out and testing becomes very difficult.

Invoking is bad, event passage might be slightly better but still requires some very smelly code to do it.

The documentation at caliburnmicro.com are pretty clear and the examples on the github repository are pretty thorough for ideals that are in place for CMs usage.