How do I select a collection within a collection using LINQ?

Question

I have the following structure.

public class ToolSettings
{
  public string Extension { get; set; }
  public ObservableCollection<Tool> Tools { get; set; }
}

public class Tool
{
  public string Name { get; set; }
  public string Command { get set; }
}

// Within app code
public ObservableCollection<ToolSettings> settings { get; set; }

I'd like to grab the Tools collection from the settings collection where the Extension equals a certain string.

Below is my LINQ code, but I'm only getting one item in my collection when I know there's more. It looks like it produces a collection of a collection, which is why there's only one item.

myListBox.ItemsSource = from i in settings 
                        where i.Extension == myExtension 
                        select i.Tools;

EDIT:

Thanks for all the good (and quick) answers. It turns out I only need the first item, but I know that the SelectMany method will come in handy in the future. So, thanks for all the heads up. Here is the full solution I used.

myListBox.ItemsSource = (from i in settings 
                         where i.Extension == myExtension 
                         select i.Tools).First();

Answer 1

myListBox.ItemsSource = settings.Where(s => s.Extension == myExtension)
                                .SelectMany(s => s.Tools);

Or, if you prefer query syntax to the fluent syntax:

myListBox.ItemsSource = from s in settings
                        where (s.Extension == myExtension)
                        from t in s.Tools
                        select t;

Answer 2

That will give you an IEnumerable<ObservableCollection<Tool>>. It willprobably only have one item in it, but that item will be a ObservableCollection. If you want that collection itself, tack .First() (or .FirstOrDefault()) at the end.

If i.Extension == myExtension could find several ToolsSettings in the collection (I'm guessing not), then you will need to use .SelectMany()