WPF DataGrid Take() not working for ItemsSource

Question

Hi, I am trying to bind a DataGrid to an Array for testing purposes. As long as I am not trying to filter anything, the auto columns work nicely.

As soon as I try to filter the array by .Take(5) or any other filter, the rows stay empty, and there are only thing horizontal lines. I think it may have something to do, with the "anonymous" class generated by the Take. But this is a wild guess...

Let me show you some code which works nicely, and does what I want:

public partial class WindowLister : UserControl
{
    private int counter = 0;
    public WindowLister()
    {
        InitializeComponent();
        dataGrid1.ItemsSource = SystemWindow.FilterToplevelWindows(filterFunction);
    }

    private bool filterFunction(SystemWindow window)
    {
        counter++;
        if (counter > 5) return false;
        return true;
    }
}

And now the version which does not work:

public partial class WindowLister : UserControl
{
    public WindowLister()
    {
        InitializeComponent();
        dataGrid1.ItemsSource = SystemWindow.FilterToplevelWindows(filterFunction).Take(5);
    }

    private bool filterFunction(SystemWindow window)
    {
        return true;
    }
}

For anyone interested, the Source used is from the very nice Lib: ManagedWinapi.Windows;

Any help is appreciated... Chris

Answer 1

I expect you need a list (Take/Where etc will give you an IEnumerable<T>/IQueryable<T> sequence). Try using .Take(5).ToList(), or .Where(...).ToList() etc (where ... is your filter).