My CollectionViewSource is not picking up changes

Question

I have a ListView which I'm binding to a CollectionViewSource in code behind with:

collectionView = CollectionViewSource.GetDefaultView(TableView.ItemsSource);
collectionView.SortDescriptions.Clear();
collectionView.SortDescriptions.Add(new SortDescription(propertyName, direction));

The TableView is the ListView, the propertyName is the name of the column I want sorted, and direction is either ascending or descending.

The XAML has the following for ItemSource:

ItemsSource="{Binding Rows}"

The code behind has the following for the Rows:

List<TableRow> rows;

public List<TableRow> Rows
{
    get { return rows; }
    set 
    {
        rows = value;
        UpdateProperty("Rows");
    }
}

the update is as follows:

public void Update()
{
     ...generate a list of rows...

     Rows = ...rows...
}

The problem occurs when the Update is called, the list view does update, but loses the sorting set previously on the CollectionViewSource.

Answer 1

If you are "newing" rows then any setting on the prior rows is gone. If you clear (not new) the rows then I think they will hold the setting.

And you don't even want Rows = rows in update. After assign rows then.

NotifyPropertyChange("Rows"); 

So the UI know to update

If you are going to new then reassign

collectionView = CollectionViewSource.GetDefaultView(TableView.ItemsSource);
collectionView.SortDescriptions.Clear();
collectionView.SortDescriptions.Add(new SortDescription(propertyName, direction));

Maybe

private List<TableRow> rows = new List<TableRow>();  

and have that the only place you new it

Answer 2

The answer is to reapply the sort descriptions after the update, as in:

collectionView = CollectionViewSource.GetDefaultView(TableView.ItemsSource);  
collectionView.SortDescriptions.Clear();
collectionView.SortDescriptions.Add(new SortDescription(propertyName, direction));

Then the sorting isn't lost. Refresh on the collection view doesn't help.