LinQ Statement for filterings

Question

Im trying to filter out an ObservableCollection<MainBusinessObject> where I need to filter all items in the collection that have Subobject.PropertyX == true.

  MainBusinessObject 
     - PropertyA int
     - PropertyB string
     - ListOfSubobject ObservableCollection<Subobject>

  Subobject
     - PropertyX bool
     - PropertyY int
     - PropertyZ - string

I really want to stay away from looping and if statements, but I can't seem to get the LinQ statements right. This is what I have so far:

return (MainBusinessObjectCollection) 
          listOfMainBusinessObject.Where(x =>
           (x as MainBusinessObject).CanBePartitioned == true);

EDIT I need to filter out the ListOfSubobject from the main business object

Answer 1

Depending if you want ANY sub-object to have that property or ALL sub-object to have that property:

var filteredList = listOfMainBusinessObject
                       .Where(x => x.ListOfSubobject.Any(s=>s.PropertyX));

or

var filteredList = listOfMainBusinessObject
                      .Where(x => x.ListOfSubobject.All(s=>s.PropertyX));

Also you have some casts that seem to be either invalid or unnecessary. To convert to a MainBusinessObjectCollection (assuming it is a collection of MainBusinessObjects), you're likely going to have to initialize it from the IEnumerable that Where returns:

var newList = new MainBusinessObjectCollection(filteredList);

Answer 2

If you want all Subobjects with Subobject.PropertyX == true:

listOfMainBusinessObject.SelectMany(x => x.ListOfSubobject)
                        .Where(x => x.PropertyX == true);