How to get Items count from CollectionViewSource?

Question

I am using CollectionViewSource to filter the records displayed in a ListBox. The xaml follows.

Answer 1

You could also do _viewSource.View.Cast<object>().Count() for the filtered list and _viewSource.View.SourceCollection.Cast<object>().Count() for the original.

Answer 2

I think the better solution is, as usual, Linq!

_viewSource.View.Cast<[your_type]>().Count();

...or...

_viewSource.View.Cast<object>().Count();

...if you don't know the items' type at runtime!

Answer 3

The source collection and collectionview both implements IEnumerable so you can always iterate over them and count how many are in them. But I would only recommend doing this if you have no access to the actual collection you used as source.

private void SetSummary() 
{
    int initialCount = 0;
    foreach(var item in _viewSource.View.SourceCollection)
    {
        initialCount++;
    }

    int filteredCount = 0;
    foreach (var item in _viewSource.View)
    {
        filteredCount++;
    }
}

Answer 4

var count = DataGrid.ItemsSource.OfType<object>().Count();

Answer 5

public static int Count(this ICollectionView view)
    {
        var index = 0;
        foreach (var unused in view)
        {
            index++;
        }
        return index;
    }

Answer 6

If you're doing MVVM, you could have your VM create a collection view rather than one being created on your behalf by the CollectionViewSource. Then, you have control over what type of CVS is created, so you can create a ListCollectionViewSource, which has a Count property. It really depends on the properties of the data you're filtering.