DataUtil

Imports System.Collections.ObjectModel
Imports System.ComponentModel
Public Class DataUtil
#Region "private members"
#Region "private fields"
    Private Shared m_categories As ObservableCollection(Of Category)
    Private Shared m_products As ObservableCollection(Of Product)
    Private Shared m_categoriesAndProducts As ObservableCollection(Of Category)
#End Region
#Region "private methods"
    Private Shared Function CreateCategories() As ObservableCollection(Of Category)
        Dim retVal As New ObservableCollection(Of Category)()
        retVal.Add(New Category With {.CategoryID = 1, .CategoryName = "Beverages", .Description = "Soft drinks, coffees, teas, beers, and ales"})
        retVal.Add(New Category With {.CategoryID = 2, .CategoryName = "Condiments", .Description = "Sweet and savory sauces, relishes, spreads, and seasonings"})
        retVal.Add(New Category With {.CategoryID = 3, .CategoryName = "Confections", .Description = "Desserts, candies, and sweet breads"})
        retVal.Add(New Category With {.CategoryID = 4, .CategoryName = "Dairy Products", .Description = "Cheeses"})
        retVal.Add(New Category With {.CategoryID = 5, .CategoryName = "Grains/Cereals", .Description = "Breads, crackers, pasta, and cereal"})
        retVal.Add(New Category With {.CategoryID = 6, .CategoryName = "Meat/Poultry", .Description = "Prepared meats"})
        retVal.Add(New Category With {.CategoryID = 7, .CategoryName = "Produce", .Description = "Dried fruit and bean curd"})
        retVal.Add(New Category With {.CategoryID = 8, .CategoryName = "Seafood", .Description = "Seaweed and fish"})
        Return retVal
    End Function
    Private Shared Function CreateProducts() As ObservableCollection(Of Product)
        Dim retVal As New ObservableCollection(Of Product)()
        retVal.Add(New Product With {.ProductID = 1, .ProductName = "Chai", .CategoryID = 1, .QuantityPerUnit = "10 boxes x 20 bags", .UnitPrice = 18D, .UnitsInStock = 39, .UnitsOnOrder = 0, .ReorderLevel = 10, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 2, .ProductName = "Chang", .CategoryID = 1, .QuantityPerUnit = "24 - 12 oz bottles", .UnitPrice = 19D, .UnitsInStock = 17, .UnitsOnOrder = 40, .ReorderLevel = 25, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 24, .ProductName = "Guaraná Fantástica", .CategoryID = 1, .QuantityPerUnit = "12 - 355 ml cans", .UnitPrice = 4.5D, .UnitsInStock = 20, .UnitsOnOrder = 0, .ReorderLevel = 0, .Discontinued = True})
        retVal.Add(New Product With {.ProductID = 77, .ProductName = "Original Frankfurter grüne Soße", .CategoryID = 2, .QuantityPerUnit = "12 boxes", .UnitPrice = 13D, .UnitsInStock = 32, .UnitsOnOrder = 0, .ReorderLevel = 15, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 61, .ProductName = "Sirop d'érable", .CategoryID = 2, .QuantityPerUnit = "24 - 500 ml bottles", .UnitPrice = 28.5D, .UnitsInStock = 113, .UnitsOnOrder = 0, .ReorderLevel = 25, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 63, .ProductName = "Vegie-spread", .CategoryID = 2, .QuantityPerUnit = "15 - 625 g jars", .UnitPrice = 43.9D, .UnitsInStock = 24, .UnitsOnOrder = 0, .ReorderLevel = 5, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 16, .ProductName = "Pavlova", .CategoryID = 3, .QuantityPerUnit = "32 - 500 g boxes", .UnitPrice = 17.45D, .UnitsInStock = 29, .UnitsOnOrder = 0, .ReorderLevel = 10, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 19, .ProductName = "Teatime Chocolate Biscuits", .CategoryID = 3, .QuantityPerUnit = "10 boxes x 12 pieces", .UnitPrice = 9.2D, .UnitsInStock = 25, .UnitsOnOrder = 0, .ReorderLevel = 5, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 20, .ProductName = "Sir Rodney's Marmalade", .CategoryID = 3, .QuantityPerUnit = "30 gift boxes", .UnitPrice = 81D, .UnitsInStock = 40, .UnitsOnOrder = 0, .ReorderLevel = 0, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 69, .ProductName = "Gudbrandsdalsost", .CategoryID = 4, .QuantityPerUnit = "10 kg pkg.", .UnitPrice = 36D, .UnitsInStock = 26, .UnitsOnOrder = 0, .ReorderLevel = 15, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 71, .ProductName = "Flotemysost", .CategoryID = 4, .QuantityPerUnit = "10 - 500 g pkgs.", .UnitPrice = 21.5D, .UnitsInStock = 26, .UnitsOnOrder = 0, .ReorderLevel = 0, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 72, .ProductName = "Mozzarella di Giovanni", .CategoryID = 4, .QuantityPerUnit = "24 - 200 g pkgs.", .UnitPrice = 34.8D, .UnitsInStock = 14, .UnitsOnOrder = 0, .ReorderLevel = 0, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 22, .ProductName = "Gustaf's Knäckebröd", .CategoryID = 5, .QuantityPerUnit = "24 - 500 g pkgs.", .UnitPrice = 21D, .UnitsInStock = 104, .UnitsOnOrder = 0, .ReorderLevel = 25, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 23, .ProductName = "Tunnbröd", .CategoryID = 5, .QuantityPerUnit = "12 - 250 g pkgs.", .UnitPrice = 9D, .UnitsInStock = 61, .UnitsOnOrder = 0, .ReorderLevel = 25, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 64, .ProductName = "Wimmers gute Semmelknödel", .CategoryID = 5, .QuantityPerUnit = "20 bags x 4 pieces", .UnitPrice = 33.25D, .UnitsInStock = 22, .UnitsOnOrder = 80, .ReorderLevel = 30, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 53, .ProductName = "Perth Pasties", .CategoryID = 6, .QuantityPerUnit = "48 pieces", .UnitPrice = 32.8D, .UnitsInStock = 0, .UnitsOnOrder = 0, .ReorderLevel = 0, .Discontinued = True})
        retVal.Add(New Product With {.ProductID = 54, .ProductName = "Tourtière", .CategoryID = 6, .QuantityPerUnit = "16 pies", .UnitPrice = 7.45D, .UnitsInStock = 21, .UnitsOnOrder = 0, .ReorderLevel = 10, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 55, .ProductName = "Pâté chinois", .CategoryID = 6, .QuantityPerUnit = "24 boxes x 2 pies", .UnitPrice = 24D, .UnitsInStock = 115, .UnitsOnOrder = 0, .ReorderLevel = 20, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 28, .ProductName = "Rössle Sauerkraut", .CategoryID = 7, .QuantityPerUnit = "25 - 825 g cans", .UnitPrice = 45.6D, .UnitsInStock = 26, .UnitsOnOrder = 0, .ReorderLevel = 0, .Discontinued = True})
        retVal.Add(New Product With {.ProductID = 7, .ProductName = "Uncle Bob's Organic Dried Pears", .CategoryID = 7, .QuantityPerUnit = "12 - 1 lb pkgs.", .UnitPrice = 30D, .UnitsInStock = 15, .UnitsOnOrder = 0, .ReorderLevel = 10, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 14, .ProductName = "Tofu", .CategoryID = 7, .QuantityPerUnit = "40 - 100 g pkgs.", .UnitPrice = 23.25D, .UnitsInStock = 35, .UnitsOnOrder = 0, .ReorderLevel = 0, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 45, .ProductName = "Rogede sild", .CategoryID = 8, .QuantityPerUnit = "1k pkg.", .UnitPrice = 9.5D, .UnitsInStock = 5, .UnitsOnOrder = 70, .ReorderLevel = 15, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 46, .ProductName = "Spegesild", .CategoryID = 8, .QuantityPerUnit = "4 - 450 g glasses", .UnitPrice = 12D, .UnitsInStock = 95, .UnitsOnOrder = 0, .ReorderLevel = 0, .Discontinued = False})
        retVal.Add(New Product With {.ProductID = 58, .ProductName = "Escargots de Bourgogne", .CategoryID = 8, .QuantityPerUnit = "24 pieces", .UnitPrice = 13.25D, .UnitsInStock = 62, .UnitsOnOrder = 0, .ReorderLevel = 20, .Discontinued = False})
        Return retVal
    End Function
    Private Shared Function CreateCategoriesAndProducts() As ObservableCollection(Of Category)
        Dim retVal As ObservableCollection(Of Category) = CreateCategories()
        Dim tempProducts As ObservableCollection(Of Product) = CreateProducts()
        Dim parentCategory As Category = Nothing
        For Each p As Product In tempProducts
            If parentCategory Is Nothing OrElse parentCategory.CategoryID <> p.CategoryID Then
                parentCategory = retVal.First(Function(category) category.CategoryID = p.CategoryID)
            End If
            parentCategory.Products.Add(p)
        Next
        Return retVal
    End Function
#End Region
#End Region
#Region "public members"
#Region "public properties"
    Public Shared ReadOnly Property Categories() As ObservableCollection(Of Category)
        Get
            If m_categories Is Nothing Then
                m_categories = CreateCategories()
            End If
            Return m_categories
        End Get
    End Property
    Public Shared ReadOnly Property Products() As ObservableCollection(Of Product)
        Get
            If m_products Is Nothing Then
                m_products = CreateProducts()
            End If
            Return m_products
        End Get
    End Property
    Public Shared ReadOnly Property CategoriesAndProducts() As ObservableCollection(Of Category)
        Get
            If m_categoriesAndProducts Is Nothing Then
                m_categoriesAndProducts = CreateCategoriesAndProducts()
            End If
            Return m_categoriesAndProducts
        End Get
    End Property
#End Region
#End Region
End Class
Public Class Category
    Implements INotifyPropertyChanged
#Region "private fields"
    Private m_categoryID As Integer
    Private m_categoryName As String
    Private m_description As String
    Private m_products As ObservableCollection(Of Product)
#End Region
#Region "public properties"
    Public Property CategoryID() As Integer
        Get
            Return Me.m_categoryID
        End Get
        Set(ByVal value As Integer)
            If Me.m_categoryID <> value Then
                Me.m_categoryID = value
                OnPropertyChanged("CategoryID")
            End If
        End Set
    End Property
    Public Property CategoryName() As String
        Get
            Return Me.m_categoryName
        End Get
        Set(ByVal value As String)
            If Me.m_categoryName <> value Then
                Me.m_categoryName = value
                OnPropertyChanged("CategoryName")
            End If
        End Set
    End Property
    Public Property Description() As String
        Get
            Return Me.m_description
        End Get
        Set(ByVal value As String)
            If Me.m_description <> value Then
                Me.m_description = value
                OnPropertyChanged("Description")
            End If
        End Set
    End Property
    Public ReadOnly Property Products() As ObservableCollection(Of Product)
        Get
            If m_products Is Nothing Then
                m_products = New ObservableCollection(Of Product)()
            End If
            Return Me.m_products
        End Get
    End Property
#End Region
#Region "INotifyPropertyChanged Members"
    Public Event PropertyChanged(ByVal sender As Object, ByVal e As PropertyChangedEventArgs) Implements INotifyPropertyChanged.PropertyChanged
    Protected Overridable Sub OnPropertyChanged(ByVal propertyName As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
    End Sub
#End Region
End Class
Public Class Product
    Implements INotifyPropertyChanged
#Region "INotifyPropertyChanged Members"
    Public Event PropertyChanged(ByVal sender As Object, ByVal e As PropertyChangedEventArgs) Implements INotifyPropertyChanged.PropertyChanged
    Protected Overridable Sub OnPropertyChanged(ByVal propertyName As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
    End Sub
#End Region
#Region "private members"
    Private m_productID As Integer
    Private m_productName As String
    Private m_categoryID As Integer
    Private m_quantityPerUnit As String
    Private m_unitPrice As Decimal
    Private m_unitsInStock As Integer
    Private m_unitsOnOrder As Integer
    Private m_reorderLevel As Integer
    Private m_discontinued As Boolean
#End Region
#Region "public properties"
    Public Property ProductID() As Integer
        Get
            Return Me.m_productID
        End Get
        Set(ByVal value As Integer)
            If Me.m_productID <> value Then
                Me.m_productID = value
                OnPropertyChanged("ProductID")
            End If
        End Set
    End Property
    Public Property ProductName() As String
        Get
            Return Me.m_productName
        End Get
        Set(ByVal value As String)
            If Me.m_productName <> value Then
                Me.m_productName = value
                OnPropertyChanged("ProductName")
            End If
        End Set
    End Property
    Public Property CategoryID() As Integer
        Get
            Return Me.m_categoryID
        End Get
        Set(ByVal value As Integer)
            If Me.m_categoryID <> value Then
                Me.m_categoryID = value
                OnPropertyChanged("CategoryID")
            End If
        End Set
    End Property
    Public Property QuantityPerUnit() As String
        Get
            Return Me.m_quantityPerUnit
        End Get
        Set(ByVal value As String)
            If Me.m_quantityPerUnit <> value Then
                Me.m_quantityPerUnit = value
                OnPropertyChanged("QuantityPerUnit")
            End If
        End Set
    End Property
    Public Property UnitPrice() As Decimal
        Get
            Return Me.m_unitPrice
        End Get
        Set(ByVal value As Decimal)
            If value < 0 Then
                Throw New Exception("Negative numbers are not allowed")
            End If
            Me.m_unitPrice = value
            OnPropertyChanged("UnitPrice")
        End Set
    End Property
    Public Property UnitsInStock() As Integer
        Get
            Return Me.m_unitsInStock
        End Get
        Set(ByVal value As Integer)
            If value < 0 Then
                Throw New Exception("Negative numbers are not allowed")
            End If
            Me.m_unitsInStock = value
            OnPropertyChanged("UnitsInStock")
        End Set
    End Property
    Public Property UnitsOnOrder() As Integer
        Get
            Return Me.m_unitsOnOrder
        End Get
        Set(ByVal value As Integer)
            If Me.m_unitsOnOrder <> value Then
                Me.m_unitsOnOrder = value
                OnPropertyChanged("UnitsOnOrder")
            End If
        End Set
    End Property
    Public Property ReorderLevel() As Integer
        Get
            Return Me.m_reorderLevel
        End Get
        Set(ByVal value As Integer)
            If Me.m_reorderLevel <> value Then
                Me.m_reorderLevel = value
                OnPropertyChanged("ReorderLevel")
            End If
        End Set
    End Property
    Public Property Discontinued() As Boolean
        Get
            Return Me.m_discontinued
        End Get
        Set(ByVal value As Boolean)
            If Me.m_discontinued <> value Then
                Me.m_discontinued = value
                OnPropertyChanged("Discontinued")
            End If
        End Set
    End Property
#End Region
End Class

using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System;
namespace IGDocumentation
{
    public class DataUtil
    {
        #region private members
        #region private fields
        private static ObservableCollection<Category> categories;
        private static ObservableCollection<Product> products;
        private static ObservableCollection<Category> categoriesAndProducts;
        #endregion
        #region private methods
        private static ObservableCollection<Category> CreateCategories()
        {
            return new ObservableCollection<Category>
            {
                new Category
                {
                    CategoryID = 1,
                    CategoryName = "Beverages",
                    Description = "Soft drinks, coffees, teas, beers, and ales"
                },
                new Category
                {
                    CategoryID = 2,
                    CategoryName = "Condiments",
                    Description = "Sweet and savory sauces, relishes, spreads, and seasonings"
                },
                new Category
                {
                    CategoryID = 3,
                    CategoryName = "Confections",
                    Description = "Desserts, candies, and sweet breads",
                },
                new Category
                {
                    CategoryID = 4,
                    CategoryName = "Dairy Product",
                    Description = "Cheeses",
                },
                new Category
                {
                    CategoryID = 5,
                    CategoryName = "Grains/Cereals",
                    Description = "Breads, crackers, pasta, and cereal",
                },
                new Category
                {
                    CategoryID = 6,
                    CategoryName = "Meat/Poultry",
                    Description = "Prepared meats",
                },
                new Category
                {
                    CategoryID = 7,
                    CategoryName = "Produce",
                    Description = "Dried fruit and bean curd",
                },
                new Category
                {
                    CategoryID = 8,
                    CategoryName = "Seafood",
                    Description = "Seaweed and fish",
                }
            };
        }
        private static ObservableCollection<Product> CreateProducts()
        {
            return new ObservableCollection<Product>
            {
                new Product
                {
                    ProductID = 1,
                    ProductName = "Chai",
                    CategoryID = 1,
                    QuantityPerUnit = "10 boxes x 20 bags",
                    UnitPrice = 18.0000m,
                    UnitsInStock = 39,
                    UnitsOnOrder = 0,
                    ReorderLevel = 10,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 2,
                    ProductName = "Chang",
                    CategoryID = 1,
                    QuantityPerUnit = "24 - 12 oz bottles",
                    UnitPrice = 19.0000m,
                    UnitsInStock = 17,
                    UnitsOnOrder = 40,
                    ReorderLevel = 25,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 24,
                    ProductName = "Guaraná Fantástica",
                    CategoryID = 1,
                    QuantityPerUnit = "12 - 355 ml cans",
                    UnitPrice = 4.5000m,
                    UnitsInStock = 20,
                    UnitsOnOrder = 0,
                    ReorderLevel = 0,
                    Discontinued = true
                },
                new Product
                {
                    ProductID = 77,
                    ProductName = "Original Frankfurter grüne Soße",
                    CategoryID = 2,
                    QuantityPerUnit = "12 boxes",
                    UnitPrice = 13.0000m,
                    UnitsInStock = 32,
                    UnitsOnOrder = 0,
                    ReorderLevel = 15,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 61,
                    ProductName = "Sirop d'érable",
                    CategoryID = 2,
                    QuantityPerUnit = "24 - 500 ml bottles",
                    UnitPrice = 28.5000m,
                    UnitsInStock = 113,
                    UnitsOnOrder = 0,
                    ReorderLevel = 25,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 63,
                    ProductName = "Vegie-spread",
                    CategoryID = 2,
                    QuantityPerUnit = "15 - 625 g jars",
                    UnitPrice = 43.9000m,
                    UnitsInStock = 24,
                    UnitsOnOrder = 0,
                    ReorderLevel = 5,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 16,
                    ProductName = "Pavlova",
                    CategoryID = 3,
                    QuantityPerUnit = "32 - 500 g boxes",
                    UnitPrice = 17.4500m,
                    UnitsInStock = 29,
                    UnitsOnOrder = 0,
                    ReorderLevel = 10,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 19,
                    ProductName = "Teatime Chocolate Biscuits",
                    CategoryID = 3,
                    QuantityPerUnit = "10 boxes x 12 pieces",
                    UnitPrice = 9.2000m,
                    UnitsInStock = 25,
                    UnitsOnOrder = 0,
                    ReorderLevel = 5,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 20,
                    ProductName = "Sir Rodney's Marmalade",
                    CategoryID = 3,
                    QuantityPerUnit = "30 gift boxes",
                    UnitPrice = 81.0000m,
                    UnitsInStock = 40,
                    UnitsOnOrder = 0,
                    ReorderLevel = 0,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 69,
                    ProductName = "Gudbrandsdalsost",
                    CategoryID = 4,
                    QuantityPerUnit = "10 kg pkg.",
                    UnitPrice = 36.0000m,
                    UnitsInStock = 26,
                    UnitsOnOrder = 0,
                    ReorderLevel = 15,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 71,
                    ProductName = "Flotemysost",
                    CategoryID = 4,
                    QuantityPerUnit = "10 - 500 g pkgs.",
                    UnitPrice = 21.5000m,
                    UnitsInStock = 26,
                    UnitsOnOrder = 0,
                    ReorderLevel = 0,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 72,
                    ProductName = "Mozzarella di Giovanni",
                    CategoryID = 4,
                    QuantityPerUnit = "24 - 200 g pkgs.",
                    UnitPrice = 34.8000m,
                    UnitsInStock = 14,
                    UnitsOnOrder = 0,
                    ReorderLevel = 0,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 22,
                    ProductName = "Gustaf's Knäckebröd",
                    CategoryID = 5,
                    QuantityPerUnit = "24 - 500 g pkgs.",
                    UnitPrice = 21.0000m,
                    UnitsInStock = 104,
                    UnitsOnOrder = 0,
                    ReorderLevel = 25,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 23,
                    ProductName = "Tunnbröd",
                    CategoryID = 5,
                    QuantityPerUnit = "12 - 250 g pkgs.",
                    UnitPrice = 9.0000m,
                    UnitsInStock = 61,
                    UnitsOnOrder = 0,
                    ReorderLevel = 25,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 53,
                    ProductName = "Perth Pasties",
                    CategoryID = 6,
                    QuantityPerUnit = "48 pieces",
                    UnitPrice = 32.8000m,
                    UnitsInStock = 0,
                    UnitsOnOrder = 0,
                    ReorderLevel = 0,
                    Discontinued = true
                },
                new Product
                {
                    ProductID = 54,
                    ProductName = "Tourtière",
                    CategoryID = 6,
                    QuantityPerUnit = "16 pies",
                    UnitPrice = 7.4500m,
                    UnitsInStock = 21,
                    UnitsOnOrder = 0,
                    ReorderLevel = 10,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 55,
                    ProductName = "Pâté chinois",
                    CategoryID = 6,
                    QuantityPerUnit = "24 boxes x 2 pies",
                    UnitPrice = 24.0000m,
                    UnitsInStock = 115,
                    UnitsOnOrder = 0,
                    ReorderLevel = 20,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 28,
                    ProductName = "Rössle Sauerkraut",
                    CategoryID = 7,
                    QuantityPerUnit = "25 - 825 g cans",
                    UnitPrice = 45.6000m,
                    UnitsInStock = 26,
                    UnitsOnOrder = 0,
                    ReorderLevel = 0,
                    Discontinued = true
                },
                new Product
                {
                    ProductID = 7,
                    ProductName = "Uncle Bob's Organic Dried Pears",
                    CategoryID = 7,
                    QuantityPerUnit = "12 - 1 lb pkgs.",
                    UnitPrice = 30.0000m,
                    UnitsInStock = 15,
                    UnitsOnOrder = 0,
                    ReorderLevel = 10,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 14,
                    ProductName = "Tofu",
                    CategoryID = 7,
                    QuantityPerUnit = "40 - 100 g pkgs.",
                    UnitPrice = 23.2500m,
                    UnitsInStock = 35,
                    UnitsOnOrder = 0,
                    ReorderLevel = 0,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 45,
                    ProductName = "Rogede sild",
                    CategoryID = 8,
                    QuantityPerUnit = "1k pkg.",
                    UnitPrice = 9.5000m,
                    UnitsInStock = 5,
                    UnitsOnOrder = 70,
                    ReorderLevel = 15,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 46,
                    ProductName = "Spegesild",
                    CategoryID = 8,
                    QuantityPerUnit = "4 - 450 g glasses",
                    UnitPrice = 12.0000m,
                    UnitsInStock = 95,
                    UnitsOnOrder = 0,
                    ReorderLevel = 0,
                    Discontinued = false
                },
                new Product
                {
                    ProductID = 58,
                    ProductName = "Escargots de Bourgogne",
                    CategoryID = 8,
                    QuantityPerUnit = "24 pieces",
                    UnitPrice = 13.2500m,
                    UnitsInStock = 62,
                    UnitsOnOrder = 0,
                    ReorderLevel = 20,
                    Discontinued = false
                }
            };
        }
        private static ObservableCollection<Category> CreateCategoriesAndProducts()
        {
            ObservableCollection<Category> retVal = CreateCategories();
            ObservableCollection<Product> tempProducts = CreateProducts();
            Category parentCategory = null;
            foreach (Product p in tempProducts)
            {
                if (parentCategory == null || parentCategory.CategoryID != p.CategoryID)
                {
                    parentCategory = retVal.First<Category>(category => category.CategoryID == p.CategoryID);
                }
                parentCategory.Products.Add(p);
            }
            return retVal;
        }
        #endregion
        #endregion
        #region public members
        #region public properties
        public static ObservableCollection<Category> Categories
        {
            get
            {
                if (categories == null)
                    categories = CreateCategories();
                return categories;
            }
        }
        public static ObservableCollection<Product> Products
        {
            get
            {
                if (products == null)
                    products = CreateProducts();
                return products;
            }
        }
        public static ObservableCollection<Category> CategoriesAndProducts
        {
            get
            {
                if (categoriesAndProducts == null)
                    categoriesAndProducts = CreateCategoriesAndProducts();
                return categoriesAndProducts;
            }
        }
        #endregion
        #endregion
    }
    public class Category : INotifyPropertyChanged
    {
        #region private fields
        private int categoryID;
        private string categoryName;
        private string description;
        private ObservableCollection<Product> products;
        #endregion
        #region public properties
        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 ObservableCollection<Product> Products
        {
            get
            {
                if (products == null)
                {
                    products = new ObservableCollection<Product>();
                }
                return this.products;
            }
        }
        #endregion
        #region INotifyPropertyChanged Members
        public event PropertyChangedEventHandler PropertyChanged;
        protected virtual void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        #endregion
    }
    public class Product : INotifyPropertyChanged
    {
        #region INotifyPropertyChanged Members
        public event PropertyChangedEventHandler PropertyChanged;
        protected virtual void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        #endregion
        #region private members
        private int productID;
        private string productName;
        private int categoryID;
        private string quantityPerUnit;
        private decimal unitPrice;
        private int unitsInStock;
        private int unitsOnOrder;
        private int reorderLevel;
        private bool discontinued;
        #endregion
        #region public properties
        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 int CategoryID
        {
            get
            {
                return this.categoryID;
            }
            set
            {
                if (this.categoryID != value)
                {
                    this.categoryID = value;
                    OnPropertyChanged("CategoryID");
                }
            }
        }
        public string QuantityPerUnit
        {
            get
            {
                return this.quantityPerUnit;
            }
            set
            {
                if (this.quantityPerUnit != value)
                {
                    this.quantityPerUnit = value;
                    OnPropertyChanged("QuantityPerUnit");
                }
            }
        }
        public decimal UnitPrice
        {
            get
            {
                return this.unitPrice;
            }
            set
            {
                if (value < 0)
                    throw new Exception("Negative numbers are not allowed.");
                this.unitPrice = value;
                OnPropertyChanged("UnitPrice");
            }
        }
        public int UnitsInStock
        {
            get
            {
                return this.unitsInStock;
            }
            set
            {
                if (value < 0)
                    throw new Exception("Negative numbers are not allowed.");
                    this.unitsInStock = value;
                    OnPropertyChanged("UnitsInStock");
            }
        }
        public int UnitsOnOrder
        {
            get
            {
                return this.unitsOnOrder;
            }
            set
            {
                if (this.unitsOnOrder != value)
                {
                    this.unitsOnOrder = value;
                    OnPropertyChanged("UnitsOnOrder");
                }
            }
        }
        public int ReorderLevel
        {
            get
            {
                return this.reorderLevel;
            }
            set
            {
                if (this.reorderLevel != value)
                {
                    this.reorderLevel = value;
                    OnPropertyChanged("ReorderLevel");
                }
            }
        }
        public bool Discontinued
        {
            get
            {
                return this.discontinued;
            }
            set
            {
                if (this.discontinued != value)
                {
                    this.discontinued = value;
                    OnPropertyChanged("Discontinued");
                }
            }
        }
        #endregion
    }
}