Question

I’ve been working with MVVM for a while, and this problem (if it is a problem) has me stumped all the time.

I have an ItemsControl bound to a collection in my MainViewModel

ViewModel

public class MainViewModel : ViewModelBase
{
    public ObservableCollection<string> Names { get; set; }
}

XAML

<ItemsControl ItemsSource="{Binding Names}">
  <ItemsControl.ItemTemplate>
    <DataTemplate>
      <view:NameView />
    </DataTemplate>
  </ItemsControl.ItemTemplate>
</ItemsControl>

The DataContext property of each is of type string (bound directly to the Model), but what if I wanted the DataContext’s to be bound to a ViewModel which is based on the property. How would I go about instantiating the ViewModel and feeding it the Model (string).

I hope that makes sense.

Answer 1

Why not do the following?

public ObservableCollection<NameViewModel> Names { get; set; }

This seems a bit odd, but AFAIK there isn’t a specific prohibition against one VM knowing about others.

In a case where you use DI for VM resolution, obviously your design would have to be adjusted. For instance, you might create a NamesView which is a UserControl with a public DependencyProperty of type IEnumerable<string>. Then, the NamesView‘s ViewModel is bound to this DP…