WPF MVVM accessing item bound to child view in Command implementation

Hi I implemented something I asked in a thread here WPF MVVM Master detail view with a datagrid and a TabControl

It is a master details view with a datagrid as master and TabControl as child view. The SelectedItem of the grid is bound to the ItemsSource of the TabControl.

How can I access the Item bound to the TabControl in the Command written in the开发者_JAVA技巧 viewmodel? Basically I want to add new item in the bound collection (to child). But the bound item is the selectedItem of the datagrid - how do I find which one it is.

It would help to have some detail about the command you're trying to get to work, but you should be able to bind the CommandParameter on whatever control you're using to the same DataGrid.SelectedItem property that you're using for the TabControl's ItemsSource. That CommandParameter should then be available to you as a parameter into your command handler (might look different depending on what ICommand implementation you're using - DelegateCommand, RelayCommand, etc).

Do not wire the controls directly together but introduce some kind of a proxy property in your viewmodel that both controls bind to. One of them with Mode=TwoWay.

You can use CollectionViewSource.GetDefaultView() to return the ICollectionView that the TabControl is bound to. If you set IsSynchronizedWithCurrentItem to true on the TabControl then the ICollectionView's Current property will be what you can pass in to your command

You need a property in your ViewModel called SelectedCause . Bind the SelectedItem property for your DataGrid to this SelectedCause Property. Then, instead of binding the TabControl to SelectedItem.Solutions, bind that to SelectCause.Solutions . It's better to do it this way precisely because of the problem you are having. You need a property in your ViewModel that represents the currently selected Cause. The ViewModel is meant to be a representation of the state of the View. The selected item in the DataGrid is part of that state, so you should have a SelectedCause property in your ViewModel.