Sharing state/changes across ViewModels

Posted by joshperry on Stack Overflow See other posts from Stack Overflow or by joshperry
Published on 2010-06-10T20:39:06Z Indexed on 2010/06/10 20:42 UTC
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wpf

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xaml

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mvvm

I have an App which has a Tasks tab and a Projects tab. I decided to make a separate ViewModel for each of the tabs, TasksViewModel and ProjectsViewModel.

The Tasks tab has a new task area with an associated project pulldown and the Projects tab (obviously) has a list of projects.

What I'd like is for the pulldown on the Tasks tab to share the same collection as the Projects tab list so that any time I add or remove a project on the Projects tab the list on the Tasks tab is up to date automatically. This worked well with a single ViewModel but it was beginning to become quite unruly.

Should I not have split into two ViewModels? Is there a common method of sharing data like this? Perhaps pass the same ObservableCollection<Project> into each of the ViewModels? Perhaps some type of notification back to the TasksViewModel along the lines of ICollectionChanged.

Appreciate any insight/input!

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