Visual Basic .NET Examples: Object Serialization

	Department Store: Object Serialization

Introduction to Serialization

In traditional file processing supported by most compiled languages such as C#, you learn to create values from primitive types (int, double, char, etc) and save them to a medium. Many libraries such as MFC, VCL, and the .NET Framework provide built-in classes you can use to save a variable of your class as if the variable had been created from a primitive data type.

Object serialization consists of saving the state of any object as a whole. Serialization makes it possible to easily create a file-based database since you are able to save and restore the object the same way you would use file processing of primitive types.

Practical Learning: Introducing File-Based Databases

Start a new Windows Forms Application named DepartmentStore3
To add a new form, on the main menu, click Project -> Add Windows Form...
In the Templates list of the Add New Item dialog box, make sure Windows Form is selected.
Set the Name to NewStoreItem and press Enter

Design the form as follows:

Control	Name	Text	Other Properties
Label		Item #:
TextBox	txtItemNumber
Label		Item Name:
TextBox	txtItemName
Label		Size:
TextBox	txtSize
Label		Unit Price:
TextBox	txtUnitPrice		AlignText: Right
Button	btnAddItem	Add Item
Button	btnClose	Close
Form			AcceptButton: btnAddItem MaximizeBox: False StartPosition: CenterScreen

Arrange the Tab Order (View . Tab Order) so the Item # text box is the last in the sequence:

Double-click an unoccupied area of the form and implement its Click event as follows:

Dim lstStoreItems As ArrayList

Private Sub NewStoreItem_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        lstStoreItems = New ArrayList
End Sub

In the Class Name combo box, select btnClose
In the Method Name combo box, select Click

Implement the event as follows:

Private Sub btnClose_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnClose.Click
        Close()
End Sub

Display the first form (Form1.vb [Design])
Add a button to it with the following properties:
Text: New Store Item
Name: btnNewStoreItem

Double-click the New Store Item button and implement its Click event as follows:

Private Sub btnNewStoreItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnNewStoreItem.Click
        Dim frmNewItem As New NewStoreItem

        frmNewItem.Show()
End Sub

Add a new Windows Form
Set its Name to StoreInventory and press Enter

Design the form as follows:

Control	Name	Text	Other Properties
DataGrid			Auto Format: Colorful 3
Button	bntLoad	Load
Button	btnClose	Close
Form			AcceptButton: bntLoad MaximizeBox: False StartPosition: CenterScreen

Double-click the Close button and implement its Click event as follows:

Private Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
        Close()
End Sub

Display the first form (Form1.vb [Design])
Add a button to it with the following properties:
Text: Store Inventory
Name: btnStoreInventory
Double-click the Store Inventory button

Implement its Click event as follows:

Private Sub btnStoreInventory_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStoreInventory.Click
        Dim frmInventory As New StoreInventory

        frmInventory.Show()
End Sub

Add a new Windows Form and name it CustomerOrder

Design the form as follows:

Control	Name	Text	Other Properties
Label		Item #
Label		Description
Label		Size
Label		Unit Price
Label		Qty
Label		Sub-Total
TextBox	txtItemNumber1
TextBox	txtDescription1
TextBox	txtSize1
TextBox	txtUnitPrice1	0.00	TextAlign: Right
TextBox	txtQuantity1	0	TextAlign: Right
TextBox	txtSubTotal1	0.00	TextAlign: Right
TextBox	txtItemNumber2
TextBox	txtDescription2
TextBox	txtSize2
TextBox	txtUnitPrice2	0.00	TextAlign: Right
TextBox	txtQuantity2	0	TextAlign: Right
TextBox	txtSubTotal2	0.00	TextAlign: Right
TextBox	txtItemNumber3
TextBox	txtDescription3
TextBox	txtSize3
TextBox	txtUnitPrice3	0.00	TextAlign: Right
TextBox	txtQuantity3	0	TextAlign: Right
TextBox	txtSubTotal3	0.00	TextAlign: Right
TextBox	txtItemNumber4
TextBox	txtDescription4
TextBox	txtSize4
TextBox	txtUnitPrice4	0.00	TextAlign: Right
TextBox	txtQuantity4	0	TextAlign: Right
TextBox	txtSubTotal4	0.00	TextAlign: Right
TextBox	txtItemNumber5
TextBox	txtDescription5
TextBox	txtSize5
TextBox	txtUnitPrice5	0.00	TextAlign: Right
TextBox	txtQuantity5	0	TextAlign: Right
TextBox	txtSubTotal5	0.00	TextAlign: Right
TextBox	txtItemNumber6
TextBox	txtDescription6
TextBox	txtSize6
TextBox	txtUnitPrice6	0.00	TextAlign: Right
TextBox	txtQuantity6	0	TextAlign: Right
TextBox	txtSubTotal6	0.00	TextAlign: Right
TextBox	txtItemNumber7
TextBox	txtDescription7
TextBox	txtSize7
TextBox	txtUnitPrice7	0.00	TextAlign: Right
TextBox	txtQuantity7	0	TextAlign: Right
TextBox	txtSubTotal7	0.00	TextAlign: Right
TextBox	txtItemNumber8
TextBox	txtDescription8
TextBox	txtSize8
TextBox	txtUnitPrice8	0.00	TextAlign: Right
TextBox	txtQuantity8	0	TextAlign: Right
TextBox	txtSubTotal8	0.00	TextAlign: Right
Label		This order will be saved in
DateTimePicker	dtpSaleDate		Format: Custom CustomFormat: ddd dd MMM yyyy
Label		Total Order:
TextBox	txtTotalOrder	0.00	TextAlign: Right
Button	btnSave	Save and Start a New Order
Button	btnClose	Close

Double-click the Close button and implement its Click event as follows:

Private Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
        Close()
End Sub

Display the first form (Form1.vb [Design])
Add a button to it with the following properties:
Text: New Customer Order
Name: btnNewOrder
Double-click the New Customer Order button

Implement its Click event as follows:

Private Sub btnNewOrder_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnNewOrder.Click
        Dim frmOrder As New CustomerOrder

        frmOrder.Show()
End Sub

Add a new Windows Form and name it DailySales

Design the form as follows:

Control	Name	Text	Other Properties
Label		View Sales For
DateTimePicker	dtpSaleDate		Format: Custom CustomFormat: ddd dd MMM yyyy
DataGrid			Auto Format: Colorful 3
Button	btnClose	Close
Form			MaximizeBox: False StartPosition: CenterScreen

Double-click the Close button and implement its Click event as follows:

Private Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
        Close()
End Sub

Display the first form (Form1.vb [Design])
Add a button to it with the following properties:
Text: View Daily Sales
Name: btnDailySales
Double-click the View Daily Sales button

Implement its Click event as follows:

Private Sub btnDailySales_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnDailySales.Click
        Dim frmSales As New DailySales

        frmSales.Show()
End Sub

Return to the main form. Add a new button to it and set its properties as follows:
Text: Close
Name: btnClose

Double-click the Close button and implement its Click event as follows:

Private Sub btnClose_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnClose.Click
        End
End Sub

Save all

Binary Serialization

The .NET Framework provides all means of serializing any managed class through a concept referred to as binary serialization. To proceed with object serialization, you must first specify the object you would use. As with any other program, you can either use one of the classes built-in the .NET Framework or you can use your own programmer-created class. If you decide to use your own class, you can specify whether the whole class or just some parts of the class can be saved.

Binary serialization consists of saving an object. This object is usually a class that either you create or is provided through the .NET Framework. For a class to be serializable, it must be marked with the Serializable attribute. This means that, when checking the MSDN documentation, any class you see with this attribute is already configured to be serialized. This is the case for almost all list-oriented classes such as Array, ArrayList, etc, including many of the classes we will use when we start studying ADO .NET and relational databases.

If you create your own class and want to be able to save values from its variables, you can (must) mark the class with the Serializable attribute. To do this, type [Serializable] before starting to create the class.

The Serializable attribute informs the compiler that values from the class can be serialized. When creating a serializable class, you have the ability to specify whether all of the member variables of the class can be serialized or just some of them.

Practical Learning: Creating a Serializable Class

To add a new project, on the main menu, click File -> Add Project -> New Project...
In the Project Types list of the Add New Project dialog box, make sure Visual C# Projects is selected
In the Templates list, click Class Library
Change the Name to StoreItemR2
Click OK

Change the file as follows:

<Serializable()> Public Class CStoreItem
    Private nbr As String
    Private nm As String
    Private sz As String
    Private uprice As Double

    Public Sub New()
        nbr = ""
        nm = ""
        sz = ""
        uprice = 0.0
    End Sub

    Public Sub New(ByVal number As String, ByVal name As String, _
                   ByVal size As String, ByVal price As Double)
        nbr = number
        nm = name
        size = sz
        uprice = price
    End Sub

    Public Property ItemNumber() As String
        Get
            Return nbr
        End Get
        Set(ByVal Value As String)
            nbr = Value
        End Set
    End Property

    Public Property ItemName() As String
        Get
            Return nm
        End Get
        Set(ByVal Value As String)
            nm = Value
        End Set
    End Property

    Public Property ItemSize() As String
        Get
            Return sz
        End Get
        Set(ByVal Value As String)
            sz = Value
        End Set
    End Property

    Public Property UnitPrice() As Double
        Get
            Return uprice
        End Get
        Set(ByVal Value As Double)
            uprice = Value
        End Set
    End Property
End Class

To create the library, in the Solution Explorer, right-click the StoreItemR2 node and click Build
To get a reference of this library to the department store project, in Solution Explorer, under DepartmentStore3, right-click References and click Add Reference...
In the Add Reference dialog box, click the Projects property page and make sure the StoreItemR2 project is selected:
Click Select and click OK

Change the Load event of the New Store Item form as follows:

Private Sub NewStoreItem_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        lstStoreItems = New ArrayList

        Dim tmeNow As Date = Now

        ' Get ready to create a random number
        Dim strItemNumber As String = "000000"

        Dim mls As Integer = tmeNow.Millisecond
        ' Generate two random numbers between 100 and 999
        Dim rndNumber As New Random(mls)
        Dim NewNumber1 As Integer = rndNumber.Next(100, 999)
        Dim NewNumber2 As Integer = rndNumber.Next(100, 999)
        ' Create an item number from the random numbers
        strItemNumber = NewNumber1.ToString() + "-" + NewNumber2.ToString()

        ' Display the created item number in the Item # text box
        Me.txtItemNumber.Text = strItemNumber
End Sub

Display the Customer Order form. Right-click it and click View Code
In the top section of the file, type Imports StoreItemR2 as the first line of the file

Create the following function above the End Class line:

Private Function LocateStoreItem(ByVal ItemNumber As String) As StoreItemR2.CStoreItem
        Dim item As New StoreItemR2.CStoreItem
        Dim i As Integer

        ' Get a list of all items in the store
        For i = 0 To lstAvailableItems.Count Step 1
            ' Get a reference to the current item
            item = lstAvailableItems(i)

            ' If the Item Number of the current item matches the argument,
            ' then return it
            If item.ItemNumber = ItemNumber Then
                Return item
            End If
        Next

        ' If the item was not found, then return nothing;
        Return Nothing
    End Function

In the same way, create the following function above the End Class line:

Private Sub CalculateTotalOrder()
        Dim subTotal1 As Double
        Dim subTotal2 As Double
        Dim subTotal3 As Double
        Dim subTotal4 As Double
        Dim subTotal5 As Double
        Dim subTotal6 As Double
        Dim subTotal7 As Double
        Dim subTotal8 As Double
        Dim orderTotal As Double

        ' Retrieve the value of each sub total
        subTotal1 = CDbl(Me.txtSubTotal1.Text)
        subTotal2 = CDbl(Me.txtSubTotal2.Text)
        subTotal3 = CDbl(Me.txtSubTotal3.Text)
        subTotal4 = CDbl(Me.txtSubTotal4.Text)
        subTotal5 = CDbl(Me.txtSubTotal5.Text)
        subTotal6 = CDbl(Me.txtSubTotal6.Text)
        subTotal7 = CDbl(Me.txtSubTotal7.Text)
        subTotal8 = CDbl(Me.txtSubTotal8.Text)

        ' Calculate the total value of the sub totals
        orderTotal = subTotal1 + subTotal2 + subTotal3 + _
                             subTotal4 + subTotal5 + subTotal6 + _
                            subTotal7 + subTotal8

        ' Display the total order in the appropriate text box
        Me.txtTotalOrder.Text = orderTotal.ToString("F")
End Sub

In the Class Name combo box, select txtItemNumber1