Product Data

public class Product : ObservableModel
{
    private int _productID;
    private string _productName;
    private Category _category;
    public int ProductID
    {
        get
        {
            return this._productID;
        }
        set
        {
            if (this._productID != value)
            {
                this._productID = value;
                OnPropertyChanged("ProductID");
            }
        }
    }
    public string ProductName
    {
        get
        {
            return this._productName;
        }
        set
        {
            if (this._productName != value)
            {
                this._productName = value;
                OnPropertyChanged("ProductName");
            }
        }
    }
    public Category Category
    {
        get
        {
            return this._category;
        }
        set
        {
            if (this._category != value)
            {
                this._category = value;
                OnPropertyChanged("Category");
            }
        }
    }
}
public class Category : ObservableModel
{
    private int _categoryID;
    private string _categoryName;
    private string _description;
    public int CategoryID
    {
        get
        {
            return this._categoryID;
        }
        set
        {
            if (this._categoryID != value)
            {
                this._categoryID = value;
                OnPropertyChanged("CategoryID");
            }
        }
    }
    public string CategoryName
    {
        get
        {
            return this._categoryName;
        }
        set
        {
            if (this._categoryName != value)
            {
                this._categoryName = value;
                OnPropertyChanged("CategoryName");
            }
        }
    }
    public string Description
    {
        get
        {
            return this._description;
        }
        set
        {
            if (this._description != value)
            {
                this._description = value;
                OnPropertyChanged("Description");
            }
        }
    }
}

public class ProductData
{
    private static ObservableCollection<Product> _products;
    public static ObservableCollection<Product> Products
    {
        get
        {
            if (_products == null)
            {
                _products = CreateProducts();
            }
            return _products;
        }
    }
    private static ObservableCollection<Product> CreateProducts()
    {
        return new ObservableCollection<Product>
        {
            new Product
            {
                ProductID = 1,
                ProductName = "Chai",
                Category = new Category()
                {
                    CategoryID = 1,
                    CategoryName = "Beverages",
                    Description = "Soft drinks, coffees, teas, beers, and ales"
                },
            },
            new Product
            {
                ProductID = 2,
                ProductName = "Chang",
                Category = new Category()
                {
                    CategoryID = 1,
                    CategoryName = "Beverages",
                    Description = "Soft drinks, coffees, teas, beers, and ales"
                },
             },
             new Product
             {
                 ProductID = 77,
                 ProductName = "Original Frankfurter grune So?e",
                 Category = new Category()
                 {
                     CategoryID = 2,
                     CategoryName = "Condiments",
                     Description = "Sweet and savory sauces, relishes, spreads, and seasonings"
                 },
              },
              new Product
              {
                  ProductID = 72,
                  ProductName = "Mozzarella di Giovanni",
                  Category = new Category()
                  {
                      CategoryID = 4,
                      CategoryName = "Dairy Product",
                      Description = "Cheeses"
                  },
              },
            };
        }
}

public class ObservableModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

Public Class Product
    Inherits ObservableModel
    Private _productID As Integer
    Private _productName As String
    Private _category As Category
    Public Property ProductID() As Integer
      Get
            Return Me._productID
      End Get
      Set
            If Me._productID <> value Then
                  Me._productID = value
                  OnPropertyChanged("ProductID")
            End If
      End Set
End Property
Public Property ProductName() As String
      Get
            Return Me._productName
      End Get
      Set
            If Me._productName <> value Then
                  Me._productName = value
                  OnPropertyChanged("ProductName")
            End If
      End Set
End Property
Public Property Category() As Category
      Get
            Return Me._category
      End Get
      Set
            If Me._category IsNot value Then
                  Me._category = value
                  OnPropertyChanged("Category")
            End If
      End Set
End Property
End Class
Public Class Category
    Inherits ObservableModel
    Private _categoryID As Integer
    Private _categoryName As String
    Private _description As String
    Public Property CategoryID() As Integer
      Get
            Return Me._categoryID
      End Get
      Set
            If Me._categoryID <> value Then
                  Me._categoryID = value
                  OnPropertyChanged("CategoryID")
            End If
      End Set
End Property
Public Property CategoryName() As String
      Get
            Return Me._categoryName
      End Get
      Set
            If Me._categoryName <> value Then
                  Me._categoryName = value
                  OnPropertyChanged("CategoryName")
            End If
      End Set
End Property
Public Property Description() As String
      Get
            Return Me._description
      End Get
      Set
            If Me._description <> value Then
                  Me._description = value
                  OnPropertyChanged("Description")
            End If
      End Set
End Property
End Class

Public Class ProductData
    Private Shared _products As ObservableCollection(Of Product)
    Public Shared ReadOnly Property Products() As ObservableCollection(Of Product)
      Get
          If _products Is Nothing Then
            _products = CreateProducts()
          End If
          Return _products
      End Get
    End Property
    Private Shared Function CreateProducts() As ObservableCollection(Of Product)
      Return New ObservableCollection(Of Product)() From {
          New Product() With {
            .ProductID = 1,
            .ProductName = "Chai",
            .Category = New Category() With {
                  .CategoryID = 1,
                  .CategoryName = "Beverages",
                  .Description = "Soft drinks, coffees, teas, beers, and ales"
                        }
          },
          New Product() With {
            .ProductID = 2,
            .ProductName = "Chang",
            .Category = New Category() With {
                  .CategoryID = 1,
                  .CategoryName = "Beverages",
                  .Description = "Soft drinks, coffees, teas, beers, and ales"
                  }
          },
          New Product() With {
            .ProductID = 77,
            .ProductName = "Original Frankfurter grune So?e",
            .Category = New Category() With {
                  .CategoryID = 2,
                  .CategoryName = "Condiments",
                  .Description = "Sweet and savory sauces, relishes, spreads, and seasonings"
                  }
          },
          New Product() With {
            .ProductID = 72,
            .ProductName = "Mozzarella di Giovanni",
            .Category = New Category() With {
                  .CategoryID = 4,
                  .CategoryName = "Dairy Product",
                  .Description = "Cheeses"
                  }
          }
      }
    End Function
End Class