WPF - DataGrid non aggiorna la variabile Binding C#

Mi è capitato di avere il seguente problema:
Ho una DataGrid  che binda ad una Collection, ma modificando un parametro questo non viene aggiornato nella collection. Casualmente mi sono imbattuto nel seguente consiglio:
http://stackoverflow.com/questions/17211462/wpf-bound-datagrid-does-not-update-items-properties 


La soluzione è molto semplice ed è quella di far ereditare alla classe degli item la

ObservableCollection

Ecco l'esempio:

Code:

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel; // ObservableCollection
using System.ComponentModel; // INotifyPropertyChanged
using System.Collections.Specialized; // NotifyCollectionChangedEventHandler
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ObservableCollectionTest
{
    class Program
    {
        static void Main(string[] args)
        {
            // ATTN: Please note it's a "TrulyObservableCollection" that's instantiated. Otherwise, "Trades[0].Qty = 999" will NOT trigger event handler "Trades_CollectionChanged" in main.
            // REF: http://stackoverflow.com/questions/8490533/notify-observablecollection-when-item-changes
            TrulyObservableCollection<Trade> Trades = new TrulyObservableCollection<Trade>();
            Trades.Add(new Trade { Symbol = "APPL", Qty = 123 });
            Trades.Add(new Trade { Symbol = "IBM", Qty = 456});
            Trades.Add(new Trade { Symbol = "CSCO", Qty = 789 });

        Trades.CollectionChanged += Trades_CollectionChanged;
        Trades.ItemPropertyChanged += PropertyChangedHandler;
        Trades.RemoveAt(2);

        Trades[0].Qty = 999;

        Console.WriteLine("Hit any key to exit");
        Console.ReadLine();

        return;
    }

    static void PropertyChangedHandler(object sender, PropertyChangedEventArgs e)
    {
        Console.WriteLine(DateTime.Now.ToString() + ", Property changed: " + e.PropertyName + ", Symbol: " + ((Trade) sender).Symbol + ", Qty: " + ((Trade) sender).Qty);
        return;
    }

    static void Trades_CollectionChanged(object sender, EventArgs e)
    {
        Console.WriteLine(DateTime.Now.ToString() + ", Collection changed");
        return;
    }
}

#region TrulyObservableCollection
public class TrulyObservableCollection<T> : ObservableCollection<T>
    where T : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler ItemPropertyChanged;

    public TrulyObservableCollection()
        : base()
    {
        CollectionChanged += new NotifyCollectionChangedEventHandler(TrulyObservableCollection_CollectionChanged);
    }

    void TrulyObservableCollection_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        if (e.NewItems != null)
        {
            foreach (Object item in e.NewItems)
            {
                (item as INotifyPropertyChanged).PropertyChanged += new PropertyChangedEventHandler(item_PropertyChanged);
            }
        }
        if (e.OldItems != null)
        {
            foreach (Object item in e.OldItems)
            {
                (item as INotifyPropertyChanged).PropertyChanged -= new PropertyChangedEventHandler(item_PropertyChanged);
            }
        }
    }

    void item_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        NotifyCollectionChangedEventArgs a = new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset);
        OnCollectionChanged(a);

        if (ItemPropertyChanged != null)
        {
            ItemPropertyChanged(sender, e);
        }
    }
}
#endregion

#region Sample entity
class Trade : INotifyPropertyChanged
{
    protected string _Symbol;
    protected int _Qty = 0;
    protected DateTime _OrderPlaced = DateTime.Now;

    public DateTime OrderPlaced
    {
        get { return _OrderPlaced; }
    }

    public string Symbol
    {
        get
        {
            return _Symbol;
        }
        set
        {
            _Symbol = value;
            NotifyPropertyChanged("Symbol");
        }
    }

    public int Qty
    {
        get
        {
            return _Qty;
        }
        set
        {
            _Qty = value;
            NotifyPropertyChanged("Qty");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    private void NotifyPropertyChanged(String propertyName = "")
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}
#endregion
}