Datagrid not updated when item property for filter changes

Question

I have a simple form with datagrid and a button. Items in the datagrid are bound to ObservableCollection of customers. The customer implements INotifyPropertyChanged interface. Each customer has a deleted property (type bool). I set a filter for the customers default view to filter out deleted customers based on the deleted property. So far it works.

Then I add an event for the button that marks selected customer as deleted. The problem is the grid is not updated after setting selected_customer.deleted = true. The deleted customer is still visible. The column bound to deleted property updates correctly. To remove the customer from the grid, I have to manually call Refresh() method of the customers default view.

Why is not the datagrid updated automaticaly when I use ObservableCollection and the customer implements INotifyPropertyChanged interface? How to make it update automatically?

Answer 1

I assume you use a CollectionViewSource for filtering. Below code will subscribe to changes to Deleted property of customer and refresh the collectioviewsource when Deleted changes. Customers is an ObservableCollection of class Customer. Customer has a bool property called Deleted and implements INotifyPropertyChanged. InitAutoRefresh() should be called before populating Customers.

private void InitAutoRefresh(ObservableCollection<Customer> observableCollection, CollectionViewSource collectionViewSource)
{
    observableCollection.CollectionChanged += 
        (sender, e) =>
        {
            foreach(Customer newItem in e.NewItems)
            {
                newItem.PropertyChanged += 
                    (sender2, e2) =>
                    {
                        if (e2.PropertyName == "Deleted")
                        {
                            collectionViewSource.View.Refresh();
                        }
                    };
            }
        };
}

Call it before you populate the observable collection. If you declared your collectionViewSource in XAML you can use FindResource to get the instance.

InitAutoRefresh(Customers, FindResource("cvsCustomers") as CollectionViewSource);