WP7 Mango上的中央datacontext与否？

Question

I'm starting to migrate one app to WP7 Mango now. One of the reasons is the database support :-)

Technically the database thing is really clear. But I'm a bit unsure where should I put my datacontext. I see primary two options:

1. global datacontext for everything
2. a separate datacontext instance per app feature

I would like to have some thoughts on that.

Thanks!

Answer 1

The demo included with the SQLite2CE tool might help you in that it gives an example of how to use datacontext and ViewModels. Visit http://sqlite2ce.codeplex.com/ and download the package, the linked articles on this page will also be a help. As a bonus, if you haven't yet converted your database from SQLite then the tool will help you with that as well.

If you take a look at the demo there's a MainViewModel (set as the datacontext of the application's MainPage.xaml) which contains an ObservableCollection for each referenced class of data. A second ViewModel is used to compile a custom set of data from the database but is still referenced though an ObservableCollection in MainViewModel. This way each control you wish to bind in XAML only needs to reference a column within the appropriate ObservableCollection object.

Answer 2

At the moment I'm would use multiple datacontext for the different features. I'll tried to use a single one through the singleton pattern. This caused some exceptions because you'll need to syncronize the SubmitChanges() calls - especially if different threads are used.