Maintaining the collection in a List/ObservableCollection

Question

i have been successfully adding an item to list in a MVVM, and now my problem is maintaining the list in the view model. Every time i navigate to a page or go back to a page and

Answer 1

Here if your ViewModel is CartingDataSource in that case it is being instatiated on every page load. Now if that is the case, then you are creating a new instance of your collection in your constructor as below:

public CartingDataSource() {


        CartData = new ObservableCollection<CartData>();

      }

As a result of which it re-initializes your collection.

You need to remove the initialization from your constructor and do something like this:

public ObservableCollection<CartData> _cartData;

public ObservableCollection<CartData> cartData
    {

     get {
            if(_cartData == null)
            {
                 _cartData = new ObservableCollection<CartData>();
            } 
         return _cartData;
         }
    set {

            _cartData = value;
       }
    }