WPF Toolkit DataGrid MultiSelect with MVVM

Question

We're using the WPF DataGrid from the WPF Toolkit and are employing MVVM. I'm finding some challenges in using MultiSelect in MVVM and am sure that I'm just missing something simple. I can use the "IsSelected" in the ViewModel to get the event when selecting a row in the DataGrid. This works fine for a single selection.

If I set "SelectionMode=Extended" I still only get the event on the selection of the first row in the DataGrid.SelectionChanged in the codebehind gets each selection event but I really want to make this work in the ViewModel. There is probably a simple solution to this multiSelect that I am just missing. I also tried binding SelectedItems (plural) to a collection to get all of these, but SelectedItems is readonly so it can't be bound to. I sure would appreciate any ideas on how to do this as I can't get this method moved from the codebehind to the ViewModel.

Answer 1

You can listen to the SelectionChanged event in the code-behind file and delegate the call to the ViewModel.

The M-V-VM pattern is not about to eliminate ALL code from the code-behind file. It’s about separating of concerns - to put view logic into the ViewModel and let the view be as stupid as possible.

If you are interested in a concrete example then you might have a look at the ViewModel sample of the WPF Application Framework (WAF).

I hope this helps.