public GroceryItemPurchase(GroceryItem gi, decimal price)
{
this.Name = gi.Name;
this.Type = gi.Type;
this.Id = Guid.NewGuid();
Price = price;
}
public void Add(GroceryItem newItem, Decimal price = 0)
{
GroceryItemPurchase gIP = new GroceryItemPurchase(newItem, price);
this.GroceryList.Add(gIP);
}