wpf - List<> collection does not update the View in MVVM

Question

I used the List<Person> collection as the ItemsSource for the DataGrid control.

But it did not update the View if i remove the item from the List collection. I was struggling for a long time for the solution.

Then Instead of the List<Person> collection in my ViewModel. I changed this into ObservableCollection<Person> collection. Now it updates the view when ever there is a change in the collection.

I am not sure why it updates only for ObservableCollection<Person> ? Anyone ?

Answer 1

Well its in the name. A simple List doesn't tell the ui to update, in other words "the view can't observe the list". There is no weird magic behind Databinding. WPF and DataBinding needs the Data model to tell them "this is new" or "this is changed", you propably already saw INotifyPropertyChanged, INotifyCollectionChanged is the same but for collections, and the List<> doesn't implement it, ObservableCollection does.