Filter ItemsSource

Question

With this code I'm setting the ItemsSource of my datagrid. However I've got more wpf controls that are needed to filter the datagrid, for example from a time range. I could write a new query for this but that seems unnecessary as the data is already available, I just need to filter it. What's the best way to do this?

Any help I could get would be really appreciated!

DateTime dateStart = CalenderSearch.SelectedDates.First();
DateTime dateEnd = CalenderSearch.SelectedDates.Last();

ObjectQuery<Fouten> fouten = eventsEntities.Foutens;

var query =
    (from fout in fouten
    where dateStart <= fout.Datum && dateEnd >= fout.Datum && fout.Rapporten.Treinen.NameTrein == trein.NameTrein
    orderby fout.Datum, fout.Time
    select new
    {
        Datum = fout.Datum,
        Time = fout.Time,
        FoutCode = fout.FoutCode,
        Omschrijving = fout.Omschrijving,
        Teller = fout.Teller,
        Module = fout.Module,
        FoutId = fout.FoutId

    }).AsEnumerable().Select(x => new Fouten
    {
        Datum = x.Datum,
        Time = x.Time,
        FoutCode = x.FoutCode,
        Omschrijving = x.Omschrijving,
        Teller = x.Teller,
        Module = x.Module,
        FoutId = x.FoutId
    }).ToList();

if (query.Count == 0)
    foutensDataGrid.ItemsSource = null;
else
    foutensDataGrid.ItemsSource = query;

Answer 1

In WPF, each collection that are used as an ItemsSource in a GUI element have an ICollectionView associated with it.
ICollectionView has a Filter property, which is of type Predicate<object>.

If you set this Filter and call Refresh() afterwards, the DataGrid will update itself to only show the items where Filter returned true.

An example how you could use this:

var collectionView = CollectionViewSource.GetDefaultView(foutensDataGrid.ItemsSource);
collectionView.Filter = o => {
    var fouten = o as Fouten;
    //do your filtering, e.g.
    return fouten.Datum <= dateEnd && fouten.Datum >= dateStart;
}
collectionView.Refresh();