Converting SelectedItems to IEnumerable<MyType>

Question

I'm using a GridView with the SelectionMode set to Multiple. I select a few items, then on my button click event, I want to process those selected items.

I'm able to grab the collection of these items with the GridView.SelectedItems property, and treat this as a generic list. I want to be able to treat this as a list of the type of underlying objects within that list.

I can validate all the items in the list are of the correct type:

if(items.Any(item => !(item is MyType))) throw new ArgumentException("Invalid list of items");

But what I'm unable to do is treat that list as anything other than a list of objects. For example:

items is IList<object> = true
items is IEnumerable<object> = true;

however

items is IList<MyType> = false
items is IEnumerable<MyType> = false

such that something like return (items as List<MyType>) fails

Short of enumerating the list and creating a new one of type MyType I'm at a loss.

var myItems = new List<MyItem>(items.Count);
foreach (var item in items)
{
    myItems.Add(item as MyItem);
}

any tips?

Answer 1

• list.Cast<MyType>() will throw exception if any single element is not of given type
• list.OfType<MyType>() will filter out by give type

Also:

• list.Count() != list.OfType<MyType>() will iterate sequence twice if it doesn't implement IList, i.e. is pure enumerator and not List or Array

Answer 2

try

items.Cast<MyType>()