Setting Up the Application

Introduction

.

Practical Learning: Introducing the Application

1. On the C: drive (or any drive of your choice) of your computer, create a folder or directory named College Park Auto-Parts (if you create it in another drive, make the changes wherever "C:\College Park Auto-Parts" is used in this project)
2. Save the following image in that folder:

   

3. Save the following icons to your computer: , , , , , , , , ,
4. Start Microsoft Visual Studio
5. Create a new Windows Forms App named CollegeParkAutoParts1
6. In the Solution Explorer, right-click the name of the project -> Add -> Folder
7. Type Models as the name of the folder and press Enter
8. To create a class, in the Solution Explorer, right-click Models -> Add -> Class...
9. Type MsgBox as the name of the file and class
10. Click Add
11. Change the class as follows:

    Public Enum Answer
        No = 0
        Yes = 1
        Cancel = 2
        Unknown = 3
    End Enum
    
    Public Class MsgBox
        Public Shared Sub Regular(message As String)
            Microsoft.VisualBasic.MsgBox(message,
                                         MsgBoxStyle.OkCancel Or MsgBoxStyle.Information,
                                         "College Park Auto-Parts")
        End Sub
    
        Public Shared Function Question(Message As String) As Answer
            Dim result As MsgBoxResult = Microsoft.VisualBasic.MsgBox(Message,
                                                                      MsgBoxStyle.YesNoCancel Or MsgBoxStyle.Question,
                                                                      "College Park Auto-Parts")
    
            Select Case result
                Case MsgBoxResult.Yes
                    Return Answer.Yes
                Case MsgBoxResult.No
                    Return Answer.No
                Case MsgBoxResult.Cancel
                    Return Answer.Cancel
                Case Else
                    Return Answer.Unknown
            End Select
        End Function
    End Class

Parts Manufacturers

The company for which we are building the application sells automobile parts. The primary piece of information you should provide for an automobile part is the manufacturer. In this section, we will create that can allow an employee to create a name for a manufacturer.

Practical Learning: Introducing Parts Manufacturers

1. To create a dialog box, on the main menu, click Project -> Add Form (Windows Forms)...
2. Set the name to Make
3. Click Add
4. Design the form as follows:

   

   Control		Text	Name	Other Properties
   Label		&Make:
   TextBox			TxtMake	Modifiers: Public
   Button		&OK	BtnOK	DialogResult: OK
   Button		&Cancel	BtnCancel	DialogResult: Cancel

   Form Characteristics

   Form Property	Value
   FormBorderStyle	FixedDialog
   Text	Make
   StartPosition	CenterScreen
   AcceptButton	BtnOK
   CancelButton	BtnCancel
   MaximizeBox	False
   MinimizeBox	False
   ShowInTaskbar	False

Parts Models

The second valuable piece of information you should provide about an object sold in a store is the model. In this section, we will create a form that an employee can use to provide that information.

Practical Learning: Introducing Parts Models

1. To create a dialog box, on the main menu, click Project -> Add Form (Windows Forms)...
2. Set the name to Model
3. Click Add
4. Design the form as follows:

   

   Control		Text	Name	Other Properties
   Label		&Model:
   TextBox			TxtModel	Modifiers: Public
   Button		&OK	BtnOK	DialogResult: OK
   Button		&Cancel	BtnCancel	DialogResult: Cancel

   Form Characteristics

   Form Property	Value
   FormBorderStyle	FixedDialog
   Text	Category Editor
   StartPosition	CenterScreen
   AcceptButton	BtnOK
   CancelButton	BtnCancel
   MaximizeBox	False
   MinimizeBox	False
   ShowInTaskbar	False

Parts Categories

A company can make objects that use the same model but some options can different items of the same model. To allow a user to provide such information, we will create a form.

Practical Learning: Introducing Parts Categories

1. To create a dialog box, on the main menu, click Project -> Add Form (Windows Forms)...
2. Set the name to Category
3. Click Add
4. Design the form as follows:

   

   Control		Text	Name	Other Properties
   Label		C&ategory:
   TextBox			TxtCategory	Modifiers: Public
   Button		&OK	BtnOK	DialogResult: OK
   Button		&Cancel	BtnCancel	DialogResult: Cancel

   Form Characteristics

   Form Property	Value
   FormBorderStyle	FixedDialog
   Text	Category
   StartPosition	CenterScreen
   AcceptButton	BtnOK
   CancelButton	BtnCancel
   MaximizeBox	False
   MinimizeBox	False
   ShowInTaskbar	False

A Class for Auto-Parts

To keep our application simple, we will conside that the business is mainly selling only automobile parts. Each part will be represented by some characteristics that we will list in a class.

Practical Learning: Creating a Class for Auto-Parts

1. To create a class, in the Solution Explorer, right-click Models -> Add -> Class...
2. Type AutoPart as the name of the file and class
3. Click Add
4. Change the class as follows:

   Public Class AutoPart
       Public Property PartNumber As Long
       Public Property Year As Integer
       Public Property Make As String
       Public Property Model As String
       Public Property Category As String
       Public Property PartName As String
       Public Property PictureFile As String
       Public Property UnitPrice As Double
   End Class

A New Store Item

A store item is an object that a store sells. When it comes to a company that sells automobile parts, the employees must create records for what the company is selling. For that reason, we will create a form that can be used to create records for the items sold in the store.

Practical Learning: Creating an Auto-Part

1. To add a new form, on the main menu, click Project -> Add Form (Windows Forms)...
2. Set the Name to StoreItemNew
3. Click Add
4. Design the form as follows:

   

   Control		(Name)	Text	Other Properties
   Label			&Part #:
   Text Box		TxtPartNumber
   Button		BtnSelectPicture	&Select Picture...
   Label		lblPictureFile	.
   Label			&Year:
   Combo Box		CbxYears
   Picture Box		PbxPartImage		BorderStyle: FixedSingle: SizeMode: AutoSize
   Label			&Make:
   Combo Box		CbxMakes
   Button		BtnNewMake	New M&ke...
   Label			M&odel:
   Combo Box		CbxModels
   Button			New Mo&del
   Label			Ca&tegory:
   Combo Box		CbxCategories
   Button		BtnNewCategory	New Cat&egory...
   Label			Part Na&me:
   Text Box		TxtPartName		ScrollBars: Vertical Multiline: True
   Label			&Unit Price
   Text Box		TxtUnitPrice
   Label			_________________
   Button		BtnSaveAutoPart	Sa&ve Auto-Part
   Button		BtnClose	&Close
   OpenFileDialog		PictureFile

5. Click an unoccupied area of the form and, in the Properties window, change the following characteristics:
   Text: College Park Auto-Parts - New Store Item
   MaximizeBox: False
   ShowInTaskbar: False
   StartPosition: CenterScreen
6. Double-click an unoccupied area of the form to generate its Load event
7. Change the document as follows:

   Imports System.IO
   Imports System.Xml.Serialization
   
   Public Class StoreItemNew
       Public Property AutoParts As List(Of AutoPart) = New List(Of AutoPart)()
   
       Private Sub InitializeAutoParts()
           Dim strFileName As String = "C:\College Park Auto-Parts10\AutoParts.xml"
           Dim XsAutoParts As XmlSerializer = New XmlSerializer(GetType(List(Of AutoPart)))
   
           Dim CarYear As Integer
   
           For CarYear = Today.Year + 1 To CarYear >= DateTime.Today.Year - 20 Step -1
               CbxYears.Items.Add(CarYear)
           Next
   
           If File.Exists(strFileName) Then
               Dim RndNumber As Random = New Random()
   
               CbxManufaturers.Items.Clear()
               CbxModels.Items.Clear()
               CbxCategories.Items.Clear()
               TxtPartName.Text = Nothing
               TxtUnitPrice.Text = Nothing
               TxtPartNumber.Text = RndNumber.Next(100000, 999999)
   
               Using FsAutoParts As FileStream = New FileStream(strFileName,
                                                                   FileMode.Open,
                                                                   FileAccess.Read,
                                                                   FileShare.Read)
                   AutoParts = CType(XsAutoParts.Deserialize(FsAutoParts), List(Of AutoPart))
   
                   Dim Counter As Integer
   
                   For Counter = 0 To AutoParts.Count
                       If Not CbxManufaturers.Items.Contains(AutoParts(Counter).Make) Then
                           CbxManufaturers.Items.Add(AutoParts(Counter).Make)
                       End If
                   Next
   
                   For Counter = 0 To AutoParts.Count
                       If Not CbxCategories.Items.Contains(AutoParts(Counter).Category)) Then
                           CbxCategories.Items.Add(AutoParts(Counter).Category)
                       End If
                   Next
               End Using
           End If
   
           LblPicturePath.Text = "C:\College Park Auto-Parts10\Generic.png"
           PbxImage.Image = Image.FromFile("C:\College Park Auto-Parts10\Generic.png")
   
           Width = PbxImage.Right + 40
           Height = PbxImage.Bottom + 75
       End Sub
   
       Private Sub StoreItemNew_Load(sender As Object, e As EventArgs) Handles MyBase.Load
           InitializeAutoParts
       End Sub
   End Class

8. Return to the New Store Item form and double-click the Select Picture button
9. Implement the event as follows:

   Private Sub BtnSelectPicture_Click(sender As Object, e As EventArgs) Handles BtnSelectPicture.Click
       If OfdPartImage.ShowDialog() = DialogResult.OK Then
           LblPicturePath.Text = OfdPartImage.FileName
           PbxImage.Image = Image.FromFile(OfdPartImage.FileName)
       Else
           PbxImage.Image = Image.FromFile("C:\College Park Auto-Parts10\Generic.png")
       End If
   
       Width = PbxImage.Right + 40
       Height = PbxImage.Bottom + 75
   End Sub

10. Return to the form and double-click the Makes combo box to generate its Selected Index event
11. Implement the event as follows:

    Private Sub CbxManufaturers_SelectedIndexChanged(sender As Object, e As EventArgs) Handles CbxManufaturers.SelectedIndexChanged
        CbxModels.Items.Clear()
        CbxModels.Text = Nothing
    
        For Each Part As AutoPart In AutoParts
            If Part.Make = CbxManufaturers.Text Then
                If Not CbxModels.Items.Contains(Part.Model) Then
                    CbxModels.Items.Add(Part.Model)
                End If
            End If
        Next
    End Sub

12. Return to the form and double-click the New Make button
13. Implement the event as follows:

    Private Sub BtnNewMake_Click(sender As Object, e As EventArgs) Handles BtnNewMake.Click
        Dim Editor As Make = New Make()
    
        If Editor.ShowDialog() = DialogResult.OK Then
            If Len(Editor.TxtMake.Text) > 0 Then
                Dim StrMake = Editor.TxtMake.Text
    
                If CbxManufaturers.Items.Contains(StrMake) Then
                    MsgBox.Regular(StrMake + " is already in the list.")
                Else
                    CbxManufaturers.Items.Add(StrMake)
                End If
    
                CbxManufaturers.Text = StrMake
            End If
        End If
    End Sub

14. Return to the form and double-click the New Model button
15. Implement the event as follows:

    Private Sub BtnNewModel_Click(sender As Object, e As EventArgs) Handles BtnNewModel.Click
        Dim Editor As Model = New Model()
    
        If Editor.ShowDialog() = DialogResult.OK Then
            If Len(Editor.TxtModel.Text) > 0 Then
                Dim StrModel = Editor.TxtModel.Text
    
                If CbxModels.Items.Contains(strModel) Then
                    MsgBox.Regular(StrModel + " is already in the list.")
                Else
                    CbxModels.Items.Add(StrModel)
                End If
    
                CbxModels.Text = StrModel
            End If
        End If
    End Sub

16. Return to the form and double-click the New Category button
17. Implement the event as follows:

    Private Sub BtnNewCategory_Click(sender As Object, e As EventArgs) Handles BtnNewCategory.Click
        Dim Editor = New Category()
    
        If Editor.ShowDialog() = DialogResult.OK Then
            If Len(Editor.TxtCategory.Text) > 0 Then
                Dim StrCategory = Editor.TxtCategory.Text
    
                If CbxCategories.Items.Contains(StrCategory) Then
                    MsgBox.Regular(StrCategory + " is already in the list.")
                Else
                    CbxCategories.Items.Add(StrCategory)
                End If
    
                CbxCategories.Text = StrCategory
            End If
        End If
    End Sub

18. Return to the form and double-click the Save Auto Part button
19. Define the event as follows:

    
    
    Private Sub BtnSaveAutoPart_Click(sender As Object, e As EventArgs) Handles BtnSaveAutoPart.Click
        ' Make sure the user had selected a year
        If String.IsNullOrEmpty(CbxYears.Text) Then
            MsgBox.Regular("You must specify the year.")
            Exit Sub
        End If
    
        ' Make sure the user had selected a make
        If String.IsNullOrEmpty(CbxManufacturers.Text) Then
            MsgBox.Regular("You must specify the car name.")
            Exit Sub
        End If
    
        ' Make sure the user had selected a model
        If String.IsNullOrEmpty(CbxModels.Text) Then
            MsgBox.Regular("You must specify the model of the car.")
            Exit Sub
        End If
    
        ' Make sure the user had entered a name/description
        If String.IsNullOrEmpty(TxtPartName.Text) Then
            MsgBox.Regular("You must enter the name (or a " &
                                "short description) for the part.")
            TxtPartName.Focus()
            Exit Sub
        End If
    
        ' Make sure the user had typed a price for the item
        If String.IsNullOrEmpty(TxtUnitPrice.Text) Then
            MsgBox.Regular("You must enter the price of the item.")
            TxtUnitPrice.Focus()
            Exit Sub
        End If
    
        Dim StrFileName As String = "C:\College Park Auto-Parts2\AutoParts.xml"
        Dim XsAutoParts As XmlSerializer = New XmlSerializer(GetType(List(Of AutoPart)))
    
        If File.Exists(StrFileName) Then
            ' If the inventory file exists, open it
    
            Using FsAutoParts As FileStream = New FileStream(StrFileName,
                                                                FileMode.Open,
                                                                FileAccess.Read,
                                                                FileShare.Read)
    
    
                ' Retrieve the list of items from file
                AutoParts = CType(XsAutoParts.Deserialize(FsAutoParts), List(Of AutoPart))
            End Using
        End If
    
        Dim Part As AutoPart = New AutoPart()
    
        Part.PartNumber = CLng(TxtPartNumber.Text)
        Part.Year = CInt(CbxYears.Text)
        Part.Make = CbxManufacturers.Text
        Part.Model = CbxModels.Text
        Part.Category = CbxCategories.Text
        Part.PartName = TxtPartName.Text
        Part.UnitPrice = CDbl(TxtUnitPrice.Text)
        Part.PictureFile = LblPicturePath.Text
    
        ' Call the Add method of our collection class to add the part
        AutoParts.Add(Part)
    
        Dim TwAutoParts As TextWriter = New StreamWriter(StrFileName)
        XsAutoParts.Serialize(TwAutoParts, AutoParts)
        TwAutoParts.Close()
    
        InitializeAutoParts()
    End Sub

20. Return to the form and double-click the Close button
21. Define the event as follows:

    Private Sub BtnClose_Click(sender As Object, e As EventArgs) Handles BtnClose.Click
        Close()
    End Sub

Application Design

Our application will have a central form from which all the regular operations are performed. To start, we will design it to show the user interface that will allow the employees to interact with the application.

Practical Learning: Designing the Application

1. In the Solution Explorer, right-click Form1.cs -> Rename
2. Type StoreInventory (to get StoreInventory.cs) and press Enter three times to display the form
3. From the Components section of the Toolbox, click ImageList and click the form
4. In the Properties window, click (Name) and type IlAutoParts
5. Click the ellipsis button of the Images field
6. In the Image Collection Editor, click Add
7. Select the following icons you had saved in your computer: Sign1, Sign2, Cliper1, Cliper2, Rulers1, Rulers2, Graph1, Graph2, Tool1, and Tool2
8. Click Open

   

9. Click OK
10. Design the form as follows:

    

    Control		(Name)	Text	Other Properties
    Label			College Park Auto-Parts	Font: Times New Roman, 24pt, style=Bold ForeColor: Blue
    PictureBox				BackColor: Black Size -> Height: 5
    GroupBox			Part Identification
    TreeView		tvwAutoParts		ImageList: AutoPartsImages
    GroupBox			Available Parts
    ListView		LvwAvailableParts		View: Details FullRowSelect: True GridLines: True
    Columns	(Name) Text TextAlign Width colAvailablePartNumber Part #   80 colAvailablePartName Part Name/Description   650 colAvailableUnitPrice Unit Price Right 100
    PictureBox		PbxPartImage		BorderStyle: FixedSingle SizeMode: AutoSize
    GroupBox			Selected Parts
    Label			Part #
    Label			Part Name
    Label			Unit Price
    Label			Qty
    Label			Sub-Total
    Text Box			TxtPartNumber
    Text Box		TxtPartName
    Text Box		TxtUnitPrice		TextAlign: Right
    Text Box		TxtQuantity		TextAlign: Right
    Text Box		TxtSubTotal		TextAlign: Right
    Button		BtnAdd	Add/Select
    ListView			LvwSelectedParts	View: Details FullRowSelect: True GridLines: True
    Columns	(Name) Text TextAlign Width colSelectedPartNumber Part #   80 colSelectedPartName Part Name/Description   600 colSelectedUnitPrice Unit Price Right 100 colSelectedQuantity Qty Right 50 colSelectedSubTotal Sub-Total Right 90
    GroupBox			Order Summary
    Button		BtnNewAutoPart	New Auto Part...
    Label			Selected Parts Total:
    Text Box		TxtSelectedPartsTotal		TextAlign: Right
    Label			Tax Rate:
    Text Box		TxtTaxRate		TextAlign: Right
    Label			Tax Amount:
    Text Box		TxtTaxAmount		TextAlign: Right
    Label			Order Total:
    Text Box		TxtOrderTotal		TextAlign: Right

11. Double-click an unoccupied area of the form
12. Change the document as follows:

    Imports System.IO
    Imports System.Xml.Serialization
    
    Public Class StoreInventory
        ' We will need a list of auto-parts.
        ' For demonstration purpose, we are creating the list as a property
        ' (but a global list Is Not necessary; we could have used local list variables).
        Public Property AutoParts As List(Of AutoPart) = New List(Of AutoPart)()
    
        ' This function Is used to reset the form
        Sub InitializeAutoParts()
            ' When the form must be reset, removes all nodes from the tree view
            TvwAutoParts.Nodes.Clear()
            ' Create the root node of the tree view
            Dim NodRoot As TreeNode = TvwAutoParts.Nodes.Add("College Park Auto-Parts",
                                                          "College Park Auto-Parts", 0, 1)
            ' Add the cars years to the tree view.
            ' Our application will deal only with the cars in the last 21 years.
            For CarYears = Today.Year + 1 To Today.Year - 20 Step -1
                NodRoot.Nodes.Add(CarYears.ToString(), CarYears.ToString(), 2, 3)
            Next
    
            ' Select the root node
            TvwAutoParts.SelectedNode = NodRoot
            ' Expand the root node
            TvwAutoParts.ExpandAll()
    
            ' AutoParts = new List<AutoPart>();
    
            ' This is the file that holds the list of auto parts
            Dim StrFileName As String = "C:\College Park Auto-Parts10\AutoParts.xml"
            Dim XsAutoParts As XmlSerializer = New XmlSerializer(GetType(List(Of AutoPart)))
    
            If File.Exists(StrFileName) Then
                ' If the inventory file exists, open it
                Using FsAutoParts As FileStream = New FileStream(StrFileName,
                                                                FileMode.Open,
                                                                FileAccess.Read,
                                                                FileShare.Read)
    
                    ' Retrieve the list of items from file
                    AutoParts = CType(XsAutoParts.Deserialize(FsAutoParts), List(Of AutoPart))
    
                    ' Show the makes nodes
                    For Each NodYear As TreeNode In NodRoot.Nodes
                        Dim LstMakes As List(Of String) = New List(Of String)()
    
                        For Each Part As AutoPart In AutoParts
    
                            If NodYear.Text = CStr(Part.Year) Then
                                If Not LstMakes.Contains(Part.Make) Then
                                    LstMakes.Add(Part.Make)
                                End If
                            End If
                        Next
    
                        For Each StrMake As String In LstMakes
                            NodYear.Nodes.Add(StrMake, StrMake, 4, 5)
                        Next
                    Next
    
                    ' Showing the models nodes
                    For Each NodYear As TreeNode In NodRoot.Nodes
                        For Each NodMake As TreeNode In NodYear.Nodes
                            Dim LstModels As List(Of String) = New List(Of String)()
    
                            For Each Part As AutoPart In AutoParts
                                If (NodYear.Text = CStr(Part.Year)) AndAlso
                                    (NodMake.Text = CStr(Part.Make)) Then
                                    If Not lstModels.Contains(Part.Model) Then
                                        lstModels.Add(Part.Model)
                                    End If
                                End If
                            Next
    
                            For Each StrModel As String In LstModels
                                NodMake.Nodes.Add(StrModel, StrModel, 6, 7)
                            Next
                        Next
                    Next
    
                    ' Showing the categories nodes
                    For Each NodYear As TreeNode In NodRoot.Nodes
                        For Each NodMake As TreeNode In NodYear.Nodes
                            For Each NodModel As TreeNode In NodMake.Nodes
                                Dim LstCategories As List(Of String) = New List(Of String)()
    
                                For Each Part As AutoPart In AutoParts
                                    If (NodYear.Text = CStr(Part.Year)) AndAlso
                                            (NodMake.Text = Part.Make) AndAlso
                                            (NodModel.Text = Part.Model) Then
                                        If Not LstCategories.Contains(Part.Category) Then
                                            LstCategories.Add(Part.Category)
                                        End If
                                    End If
                                Next
    
                                For Each StrCategory As String In LstCategories
                                    NodModel.Nodes.Add(StrCategory, StrCategory, 8, 9)
                                Next
                            Next
                        Next
                    Next
                End Using
            End If
    
            LvwSelectedParts.Items.Clear()
            LvwAvailableParts.Items.Clear()
            TxtTaxRate.Text = Nothing
            TxtPartName.Text = Nothing
            TxtQuantity.Text = Nothing
            TxtSubTotal.Text = Nothing
            TxtUnitPrice.Text = Nothing
            TxtTaxAmount.Text = Nothing
            TxtOrderTotal.Text = Nothing
            TxtPartNumber.Text = Nothing
            TxtSelectedPartsTotal.Text = Nothing
            PbxPartImage.Image = Image.FromFile("C:\College Park Auto-Parts10\Generic.png")
    
            Width = PbxPartImage.Right + 40
        End Sub
    
        Private Sub StoreInvetory_Load(sender As Object, e As EventArgs) Handles MyBase.Load
            InitializeAutoParts()
        End Sub
    End Class

13. Return to the Store Inventory form and click the Available Parts list view
14. In the Properties window, click the Events button
15. In the Events section of the Properties window for the Available Parts list view, double-click ItemSelectionChanged
16. Implement the event as follows:

    Private Sub LvwAvailableParts_ItemSelectionChanged(sender As Object, e As ListViewItemSelectionChangedEventArgs) Handles LvwAvailableParts.ItemSelectionChanged
        Dim PictureFound As Boolean = False
        Dim StrFileName As String = "C:\College Park Auto-Parts10\AutoParts.xml"
        Dim XsAutoParts As XmlSerializer = New XmlSerializer(GetType(List(Of AutoPart)))
    
        If File.Exists(StrFileName) Then
            Using FsAutoParts As FileStream = New FileStream(StrFileName,
                                                           FileMode.Open,
                                                           FileAccess.Read,
                                                           FileShare.Read)
                AutoParts = CType(XsAutoParts.Deserialize(FsAutoParts), List(Of AutoPart))
    
                For Each Part As AutoPart In AutoParts
                    If Part.PartNumber = CLng(e.Item.SubItems(0).Text) Then
                        PictureFound = True
                        PbxPartImage.Image = Image.FromFile(Part.PictureFile)
                        Exit For
                    End If
                Next
            End Using
        End If
    
        If pictureFound = False Then
            PbxPartImage.Image = Image.FromFile("C:\College Park Auto-Parts10\Generic.png")
        End If
    
        Width = PbxPartImage.Right + 40
        Height = PbxPartImage.Bottom + 75
    End Sub

17. Return to the Store Inventory form and make sure the Available Parts list view is still selected
18. In the Events section of the Properties window, double-click DoubleClick
19. Implement the event as follows:

    Private Sub LvwAvailableParts_DoubleClick(sender As Object, e As EventArgs) Handles LvwAvailableParts.DoubleClick
        Dim LviAutoPart As ListViewItem = LvwAvailableParts.SelectedItems(0)
    
        If (LvwAvailableParts.SelectedItems.Count = 0) Or
           (LvwAvailableParts.SelectedItems.Count > 1) Then
            Exit Sub
        End If
    
        TxtPartNumber.Text = LviAutoPart.Text
        TxtPartName.Text = LviAutoPart.SubItems(1).Text
        TxtUnitPrice.Text = LviAutoPart.SubItems(2).Text
    
        TxtQuantity.Text = "1"
        TxtSubTotal.Text = LviAutoPart.SubItems(2).Text
    
        TxtQuantity.Focus()
    End Sub

20. Return to the Store Inventory form and click the Unit Price text box
21. In the Events section of the Properties window, double-click Leave
22. Implement the event as follows:

    Private Sub TxtUnitPrice_Leave(sender As Object, e As EventArgs) Handles TxtUnitPrice.Leave
        Dim SubTotal As Double
        Dim UnitPrice As Double = 0
        Dim Quantity As Double = 0.00
    
        Try
            UnitPrice = CDbl(TxtUnitPrice.Text)
        Catch Fex As FormatException
            MsgBox.Regular("Invalid Unit Price!")
        End Try
    
        Try
            Quantity = CInt(TxtQuantity.Text)
        Catch Fex As FormatException
            MsgBox.Regular("Invalid Quandtity!")
        End Try
    
        SubTotal = UnitPrice * Quantity
        TxtSubTotal.Text = FormatNumber(SubTotal, 2)
    End Sub

23. Return to the Store Inventory form and click the Qty text box
24. In the Events section of the Properties window, click Leave, then click the arrow of that field and select TxtUnitPrice_Leave
25. On the Store Inventory form, click the Part # text box
26. In the Events section of the Properties window, double-click Leave
27. Implement the event as follows:

    Private Sub TxtPartNumber_Leave(sender As Object, e As EventArgs) Handles TxtPartNumber.Leave
        Dim Found = False
    
        For Each Part As AutoPart In AutoParts
            If Part.PartNumber = CLng(TxtPartNumber.Text) Then
                TxtPartName.Text = Part.PartName
    
                TxtUnitPrice.Text = Part.UnitPrice,2))
    
                If String.IsNullOrEmpty(TxtQuantity.Text) Then
                    TxtQuantity.Text = "1"
                End If
    
                TxtSubTotal.Text = FormatNumber(Part.UnitPrice, 2)
    
                TxtQuantity.Focus()
    
                Found = True
                Exit For
            End If
        Next
    
        If Found = False Then
            TxtPartName.Text = ""
            TxtUnitPrice.Text = "0.00"
            TxtQuantity.Text = "0"
            TxtSubTotal.Text = "0.00"
    
            MsgBox.Regular("There is no part with that number.")
        End If
    End Sub

28. Return to the Store Inventory form and double-click the Add/Select button
29. Implement the event as follows:

    Private Sub CalculateOrder()
        Dim PartsTotal As Double = 0.00
        Dim TaxRate As Double = 0.00
        Dim TaxAmount As Double
        Dim OrderTotal As Double
    
        If String.IsNullOrEmpty(TxtTaxRate.Text) Then
            TxtTaxRate.Text = "7.25"
        End If
    
        For Each Lvi As ListViewItem In LvwSelectedParts.Items
            Dim SubItem As ListViewItem.ListViewSubItem = Lvi.SubItems(4)
            PartsTotal = PartsTotal + SubItem.Text
        Next
    
        Try
            TaxRate = TxtTaxRate.Text / 100
        Catch Fex As FormatException
            MsgBox.Regular("Invalid Tax Rate")
        End Try
    
        TaxAmount = PartsTotal * TaxRate
        OrderTotal = PartsTotal + TaxAmount
    
        TxtSelectedPartsTotal.Text = FormatNumber(PartsTotal, 2)
        TxtTaxAmount.Text = FormatNumber(TaxAmount, 2)
        TxtOrderTotal.Text = FormatNumber(OrderTotal, 2)
    End Sub
    
    Private Sub BtnAdd_Click(sender As Object, e As EventArgs) Handles BtnAdd.Click
        If (String.IsNullOrEmpty(TxtPartNumber.Text)) Then
            MsgBox.Regular("There is no part to be added to the order.")
            Exit Sub
        End If
    
        For Each Part As AutoPart In AutoParts
            If Part.PartNumber = CLng(TxtPartNumber.Text) Then
                Dim lviSelectedPart As ListViewItem = New ListViewItem(Part.PartNumber.ToString())
    
                lviSelectedPart.SubItems.Add(Part.PartName)
                lviSelectedPart.SubItems.Add(Part.UnitPrice.ToString())
                lviSelectedPart.SubItems.Add(TxtQuantity.Text)
                lviSelectedPart.SubItems.Add(TxtSubTotal.Text)
                LvwSelectedParts.Items.Add(lviSelectedPart)
            End If
        Next
    
        CalculateOrder()
    End Sub

30. Return to the Store Inventory form and click the Selected Parts list view
31. In the Events section of the Properties window, double-click DoubleClick
32. Implement the event as follows:

    Private Sub LvwSelectedParts_DoubleClick(sender As Object, e As EventArgs) Handles LvwSelectedParts.DoubleClick
        Dim LviSelectedPart As ListViewItem = LvwSelectedParts.SelectedItems(0)
    
        If (LvwSelectedParts.SelectedItems.Count = 0) Or
        (LvwSelectedParts.SelectedItems.Count > 1) Then
            Exit Sub
        End If
    
        TxtPartNumber.Text = LviSelectedPart.Text
        TxtPartName.Text = LviSelectedPart.SubItems(1).Text
        TxtUnitPrice.Text = LviSelectedPart.SubItems(2).Text
        TxtQuantity.Text = LviSelectedPart.SubItems(3).Text
        TxtSubTotal.Text = LviSelectedPart.SubItems(4).Text
    
        LvwSelectedParts.Items.Remove(LviSelectedPart)
        CalculateOrder()
    End Sub

33. Return to the Store Inventory form and click the Part Identification tree view
34. In the Events section of the Properties window, double-click NodeMouseClick
35. Implement the event as follows:

    Private Sub TvwAutoParts_NodeMouseClick(sender As Object, e As TreeNodeMouseClickEventArgs) Handles TvwAutoParts.NodeMouseClick
        Dim NodClicked As TreeNode = e.Node
    
        If NodClicked.Level = 4 Then
            LvwAvailableParts.Items.Clear()
        End If
    
        Try
            For Each Part As AutoPart In AutoParts
                If ((Part.Category = NodClicked.Text) AndAlso
                (Part.Model = NodClicked.Parent.Text) AndAlso
                (Part.Make = NodClicked.Parent.Parent.Text) AndAlso
                (Part.Year.ToString() = NodClicked.Parent.Parent.Parent.Text)) Then
                    Dim LviAutoPart As ListViewItem = New ListViewItem(Part.PartNumber)
    
                    LviAutoPart.SubItems.Add(Part.PartName)
                    LviAutoPart.SubItems.Add(FormatNumber(Part.UnitPrice, 2))
                    LvwAvailableParts.Items.Add(LviAutoPart)
                End If
            Next
        Catch Nrf As NullReferenceException
    
        End Try
    End Sub

36. Return to the Store Inventory form and double-click the New Auto Part button
37. Implement the event as follows:

    Private Sub BtnNewAutoPart_Click(sender As Object, e As EventArgs) Handles BtnNewAutoPart.Click
        Dim Nsi As StoreItemNew = New StoreItemNew()
    
        Nsi.ShowDialog()
    
        InitializeAutoParts()
    End Sub

38. To execute the application, on the main menu, click Debug and click Start Without Debugging

    

39. Click the New Auto Part button and create some auto-parts records with the following values:

    

    Part #	Year	Make	Model	Category	Item Name	Unit Price	Picture File
    393795	2015	Buick	Regal	Alternators & Generators	DB Electrical Alternator	218.74	928037
    155975	2010	Buick	Lacrosse	Hub Assemblies	Front/Rear Wheel Hub Bearing Assembly	94.98	155975
    928374	2018	Chevrolet	Express 3500	Shocks, Struts & Suspension	Suspension Kit (Front; with 3 Groove Pitman Arm)	142.44	304031
    730283	2020	Jeep	Wrangler Unlimited Sahara	Oil Filters	Hydraulic Cylinder Timing Belt Tensioner	14.15	730283
    290741	2015	Ford	F-150 XL 3.5L V6 Flex Regular Cab 2 Full-Size Doors	Shocks, Struts & Suspension	Front Strut and Coil Spring Assembly - Set of 2	245.68	290741
    740248	2013	Chevrolet	Equinox	Bearings & Seals	Wheel hub bearing Assembly	99.95	740248
    283759	2012	Dodge	Charger 3.6L	Starters	DB Electrical SND0787 Starter	212.58	283759
    799428	2012	Cadillac	XTS	Bearings & Seals	Front/Rear Wheel Hub Bearing Assembly 5 Lugs w/ABS	79.97	799428
    648203	2018	Honda	CRV	Alternator	Alternator	202.47	593804
    502853	2014	GMC	Terrain	Bearings & Seals	Wheel Hub Bearing Assembly	48.85	927944
    520384	2020	Jeep	Wrangler Unlimited Sahara	Drum Brake	Rear Dynamic Friction Company True-Arc Brake Shoes	42.22	520384
    727394	2018	Toyota	Corolla SE 1.8L L4 Gas	Alternators	DB Electrical 400-40169 Alternator Compatible With/Replacement For 125 Internal Fan Type Decoupler Pulley Type Internal Regulator CW Rotation	215.84	727394
    927944	2017	Chevrolet	Equinox	Bearings & Seals	Wheel Hub Bearing Assembly	48.85	927944
    749471	2019	Toyota	Prius	Shocks, Struts & Suspension	2-Piece Suspension Strut and Coil Spring Kit (593024)	299.97	593024
    927307	2014	Buick	Regal	Alternators & Generators	DB Electrical Alternator	218.74	928037
    304031	2017	Chevrolet	Express 2500	Shocks, Struts & Suspension	Suspension Kit (Front; with 3 Groove Pitman Arm)	142.44	304031
    497249	2013	GMC	Sierra 1500	Drum Brake	ACDelco Gold 17960BF1 Bonded Rear Drum Brake Shoe Set	58.92	497249
    973947	2012	Honda	Accord	Brake Kits	R1 Concepts Front Rear Brakes and Rotors Kit |Front Rear Brake Pads| Brake Rotors and Pads| Ceramic Brake Pads and Rotors	292.84	973947
    182694	2016	Chevrolet	Impala	Bearings & Seals	Wheel Hub Bearing Assembly	48.85	927944
    497249	2013	Chevrolet	Silverado 1500	Drum Brake	ACDelco Gold 17960BF1 Bonded Rear Drum Brake Shoe Set	58.92	497249
    297149	2020	Jeep	Wrangler	Air Filters	ACDelco Gold A3408C Air Filter	22.83	297149
    927397	2016	Chevrolet	Impala	Bearings & Seals	Front/Rear Wheel Hub Bearing Assembly 5 Lugs w/ABS	79.97	799428
    392972	2020	Toyota	Prius AWD-e	Shocks, Struts & Suspension	2-Piece Suspension Strut and Coil Spring Kit (593024)	299.97	593024
    928037	2017	Buick	Regal	Alternators & Generators	DB Electrical Alternator	218.74	928037
    502481	2016	Chevrolet	Equinox	Bearings & Seals	Wheel hub bearing Assembly	99.95	740248
    593804	2019	Honda	Accord LX 1.5L L4 Gas	Alternator	Alternator	202.47	593804
    293748	2014	Toyota	Corolla SE 1.8L L4 Gas	Alternators	DB Electrical 400-40169 Alternator Compatible With/Replacement For 125 Internal Fan Type Decoupler Pulley Type Internal Regulator CW Rotation	215.84	727394
    639704	2021	Kia	Sorento	Brake Kits	Rear Brakes and Rotors Kit |Rear Brake Pads| Brake Rotors and Pads| Optimum OEp Brake Pads and Rotors	125.15	639704
    829385	2020	Jeep	Wrangler Unlimited Sahara	Drum Brake	Centric Brake Shoe	22.05	829385
    484695	2014	GMC	Terrain	Bearings & Seals	Front/Rear Wheel Hub Bearing Assembly 5 Lugs w/ABS	79.97	799428
    807204	2016	Chevrolet	Camaro	Alternators & Generators	DB Electrical Alternator	218.74	928037
    939283	2015	Chevrolet	Equinox	Bearings & Seals	Wheel Hub Bearing Assembly	48.85	927944
    738628	2021	Toyota	Prius AWD-e	Shocks, Struts & Suspension	2-Piece Suspension Strut and Coil Spring Kit (593024)	299.97	593024
    186950	2017	Honda	CRV	Alternator	Alternator	202.47	593804
    329573	2012	Chevrolet	Equinox	Bearings & Seals	Front/Rear Wheel Hub Bearing Assembly 5 Lugs w/ABS	79.97	799428
    594085	2015	Buick	Regal	Bearings & Seals	Front/Rear Wheel Hub Bearing Assembly 5 Lugs w/ABS	79.97	799428
    928405	2018	Chevrolet	Camaro	Alternators & Generators	DB Electrical Alternator	218.74	928037
    927937	2012	Ford	Focus SE	Starters	Duralast Starter 19481	188.88	927937
    283948	2018	GMC	Savana 3500	Shocks, Struts & Suspension	Suspension Kit (Front; with 3 Groove Pitman Arm)	142.44	304031
    495116	2020	Chrysler	Voyager	Brake Kits	Power Stop K7845 Rear Z23 Carbon Fiber Brake Pads with Drilled & Slotted Brake Rotors Kit	269.75	293748
    180400	2012	Cadillac	CTS FWD	Bearings & Seals	Front/Rear Wheel Hub Bearing Assembly 5 Lugs w/ABS	79.97	799428
    593024	2021	Toyota	Prius	Shocks, Struts & Suspension	2-Piece Suspension Strut and Coil Spring Kit (593024)	299.97	593024
    302839	2014	Chevrolet	Equinox	Bearings & Seals	Wheel Hub Bearing Assembly	48.85	927944
    649394	2020	Jeep	Wrangler Unlimited Sahara	Brake Kits	Power Stop K7940 Front Z23 Evolution Sport Brake Upgrade Kit	354.46	495116
    820684	2015	Buick	LaCrosse	Bearings & Seals	Front/Rear Wheel Hub Bearing Assembly 5 Lugs w/ABS	79.97	799428

40. Close the forms and return to your programming environment

Store Item Details

In our application, we will provide a form that an employee can use to view the information related to a certain auto part.

Practical Learning: Getting the Details of an Auto Part

1. To create a new form, on the main menu, click Project -> Add Form (Windows Forms)...
2. Set the name to StoreItemDetails
3. Click Add
4. Click an unoccupied area of the form and, in the Properties window, change the following characteristics:
   Text: College Park Auto-Parts - Store Item Details
   MaximizeBox: False
   StartPosition: CenterScreen
5. Design the form as follows:

   

   Control		(Name)	Text	Other Properties
   Label			&Part #:
   Text Box		TxtPartNumber
   Button		BtnFindAutoPart	&Find Auto-Part
   Label		lblPictureFile	Generic
   Label			&Year:
   Text Box		TxtYear
   Picture Box		PbxPartImage		BorderStyle: FixedSingle: SizeMode: AutoSize
   Label			&Make:
   Text Box		TxtMake
   Label			M&odel:
   Text Box		TxtModel
   Label			Ca&tegory:
   Text Box		TxtCategory
   Label			Part Na&me:
   Text Box		TxtPartName		ScrollBars: Vertical Multiline: True
   Label			&Unit Price
   Text Box		TxtUnitPrice
   Label			____________________
   Button		BtnClose	&Close

6. Double-click the Find Store Item button
7. Define the event as follows:

   using CollegeParkAutoParts1.Models;
   using System.Xml.Serialization;
   
   namespace CollegeParkAutoParts1
   {
       public partial class StoreItemDetails : Form
       {
           dim AutoParts as List      (             of           AutoPart)  { get; set; } = new List      (             of           AutoPart)
   
           public StoreItemDetails()
           {
               InitializeComponent()
           }
   
           private  sub    BtnFindStoreItem_Click(object sender, EventArgs e)
           {
               if               string.IsNullOrEmpty(TxtPartNumber.Text))
               {
                   MsgBox.Regular("You must enter a (valid) number for an auto-part.")
                   exit                            sub
               }
   
               bool foundAutoPart = false;
               dim StrFileName as string = "C:\College Park Auto-Parts10\AutoParts.xml"
               dim              XsAutoParts        as         XmlSerializer = new XmlSerializer(typeof(List      (             of           AutoPart)))
   
               if               File.Exists(strFileName))
               {
                   using  FsAutoParts      as    FileStream                = new(strFileName, FileMode.Open, FileAccess.Read, FileShare.Read))
                   {
                       AutoParts = (List      (             of           AutoPart))xsAutoParts.Deserialize(fsAutoParts)
   
                       for i as integer  = 0 to              AutoParts.Count; i++)
                       {
                           if               AutoParts(i).PartNumber.Equals(CLng(TxtPartNumber.Text)))
                           {
                               foundAutoPart = true;
   
                               TxtMake.Text = AutoParts(i).Make;
                               TxtModel.Text = AutoParts(i).Model;
                               TxtCategory.Text = AutoParts(i).Category;
                               TxtPartName.Text = AutoParts(i).PartName;
                               TxtYear.Text = AutoParts(i).Year.ToString()
                               TxtUnitPrice.Text = AutoParts(i).UnitPrice,2))
                               PbxPartImage.Image = Image.FromFile(AutoParts(i).PictureFile)
                               lblPictureFile.Text = AutoParts(i).PictureFile;
   
                               exit for
                           }
                       }
                   }
               }
   
               if               foundAutoPart =               false)
               {
                   MsgBox.Regular("There is no auto-part with that number in our records.")
   
                   lblPictureFile.Text = "C:\College Park Auto-Parts10\Generic.png"
                   PbxPartImage.Image = Image.FromFile(                                "C:\College Park Auto-Parts10\Generic.png")
               }
   
               Width = PbxPartImage.Right + 40
               Height = PbxPartImage.Bottom + 75
           }
       }
   }

8. Return to the Store Item Editor form and double-click the Close button
9. Define the event as follows:

   using CollegeParkAutoParts1.Models;
   using System.Xml.Serialization;
   
   namespace CollegeParkAutoParts1
   {
       public partial class StoreItemDetails : Form
       {
           ' The list of auto-parts of our database will be retrieved using a collection class.
            * This property will hold the list of auto-parts.
           dim AutoParts as List      (             of           AutoPart)  { get; set; } = new List      (             of           AutoPart)
   
           public StoreItemDetails()
           {
               InitializeComponent()
           }
   
           private  sub    BtnFindStoreItem_Click(object sender, EventArgs e)
           {
               ' When the user clicks the Find Store Item button, make sure the user typed something.
                * If the Part # text box is empty (meaning the user didn't type a number), ...*/
               if               string.IsNullOrEmpty(TxtPartNumber.Text))
               {
                   ' ... display a message box to the user, ...
                   MsgBox.Regular("You must enter a (valid) number for an auto-part.")
                   ' ... and stop everything
                   exit                            sub
               }
   
               ' This Boolean variable will allow us to know if an auto part was found.
               bool foundAutoPart = false;
               ' Our list of auto-parts is stored in an XML file.
                * Let's get a reference to that file.
               dim StrFileName as string = "C:\College Park Auto-Parts10\AutoParts.xml"
               ' We process our records through XML serialization.
                * Create a reference for XML serialization that is initialized with a collection class*/
               dim              XsAutoParts        as         XmlSerializer = new XmlSerializer(typeof(List      (             of           AutoPart)))
   
               ' Before doing anything, check whether a file of auto-parts exists
               if               File.Exists(strFileName))
               {
                   ' Create a stream reference for our file of au-parts
                   using  FsAutoParts      as    FileStream                = new(strFileName, FileMode.Open, FileAccess.Read, FileShare.Read))
                   {
                       ' If the file of auto-parts exists, open that file, get the list of 
                        * auto-parts, and store that list in our collection variable.
                       AutoParts = (List      (             of           AutoPart))xsAutoParts.Deserialize(fsAutoParts)
   
                       ' Now that the list of auto-parts exists, navigate to each item of the list
                       for i as integer  = 0 to              AutoParts.Count; i++)
                       {
                           ' When you reach an auto-part, check whether its part number is 
                            * the same as the number the user typed.*/
                           if               AutoParts(i).PartNumber.Equals(CLng(TxtPartNumber.Text)))
                           {
                               ' If the auto-part was found, make a not by updating our Boolean variable
                               foundAutoPart = true;
   
                               ' Get the values of the auto-part and display them in the Windows controls
                               TxtMake.Text = AutoParts(i).Make;
                               TxtModel.Text = AutoParts(i).Model;
                               TxtCategory.Text = AutoParts(i).Category;
                               TxtPartName.Text = AutoParts(i).PartName;
                               TxtYear.Text = AutoParts(i).Year.ToString()
                               TxtUnitPrice.Text = AutoParts(i).UnitPrice,2))
                               PbxPartImage.Image = Image.FromFile(AutoParts(i).PictureFile)
                               lblPictureFile.Text = AutoParts(i).PictureFile;
                               ' Since an auto-part was found 
                                * and its values have been displayed, stop searching.
                               exit for
                           }
                       }
                   }
               }
   
               ' Check the value of our Boolean variable. If that value is false, ...
               if               foundAutoPart =               false)
               {
                   ' ... it means no auto-part was found. Display a message box to the user
                   MsgBox.Regular("There is no auto-part with that number in our records.")
   
                   lblPictureFile.Text = "C:\College Park Auto-Parts10\Generic.png"
                   PbxPartImage.Image = Image.FromFile(                                "C:\College Park Auto-Parts10\Generic.png")
               }
   
               Width = PbxPartImage.Right + 40
               Height = PbxPartImage.Bottom + 75
           }
   
           private  sub    BtnClose_Click(object sender, EventArgs e)
           {
               Close()
           }
       }
   }

10. Display the Store Inventory form
11. Add an Auto Part Details button as follows:

    

    Control		(Name)	Text
    Button		BtnAutoPartDetails	Auto Part &Details...

12. Double-click the Auto Part Details button
13. Implement the event as follows:

    private  sub    BtnAutoPartDetails_Click(object sender, EventArgs e)
    {
        StoreItemDetails details = new StoreItemDetails()
    
        details.Show()
    }

14. To execute, on the main menu, click Debug and click Start Without Debugging:

    

15. Click the Auto Part Details button:

    

16. In the Part # text box, type 155975
17. Click the Find Store Item button:

    

18. Close the forms and return to your programming environment

Store Item EdItor

Updating a record consists of changing one or more of its details. To support this operation in our application, we will create an appropriate form.

Practical Learning: Creating a Store Item Editor

1. To create a new form, on the main menu, click Project -> Add Form (Windows Forms)...
2. Set the name to StoreItemEditor
3. Click Add
4. Click an unoccupied area of the form and, in the Properties window, change the following characteristics:
   Text: College Park Auto-Parts - Store Item Editor
   MaximizeBox: False
   StartPosition: CenterScreen
5. Resize the form to have the same size as the New Store Item form
6. Select and copy all controls from the Store Item New form
7. Paste the copied controls on the Store Item Editor form
8. Modify the design of the Store Item Editor form as follows:
    

   

   Control		(Name)	Text
   Button		BtnFindStoreItem	&Find Store Item
   Button		BtnUpdateAutoPart	Up&date Auto-Part

9. Double-click an unoccupied area of the form
10. Change the document as follows:

    using CollegeParkAutoParts1.Models;
    using System.Xml.Serialization;
    
    namespace CollegeParkAutoParts1
    {
        public partial class StoreItemEditor : Form
        {
            dim AutoParts as List      (             of           AutoPart)  { get; set; } = new List      (             of           AutoPart)
    
            public StoreItemEditor()
            {
                InitializeComponent()
            }
    
            private  sub    InitializeAutoPart()
            {
                dim StrFileName as string = "C:\College Park Auto-Parts10\AutoParts.xml"
                dim              XsAutoParts        as         XmlSerializer = new XmlSerializer(typeof(List      (             of           AutoPart)))
    
                CbxYears.Items.Clear()
    
                for CarYear as integer = DateTime.Today.Year + 1   to CarYear >= DateTime.Today.Year - 20 CarYear = CarYear -1)
                {
                    CbxYears.Items.Add(year);
                }
    
                if               File.Exists(strFileName))
                {
                    CbxMakes.Items.Clear()
                    CbxModels.Items.Clear()
                    CbxCategories.Items.Clear()
                    TxtPartName.Text = nothing
                    TxtUnitPrice.Text = nothing
                    TxtPartNumber.Text = nothing
    
                    using  FsAutoParts      as    FileStream                = new FileStream(strFileName,
                                                                   FileMode.Open,
                                                                   FileAccess.Read,
                                                                   FileShare.Read))
                    {
                        AutoParts = (List      (             of           AutoPart))xsAutoParts.Deserialize(fsAutoParts)
    
                        for i as integer  = 0 to              AutoParts.Count; i++)
                        {
                            if               not             CbxMakes.Items.Contains(AutoParts(i).Make))
                            {
                                CbxMakes.Items.Add(AutoParts(i).Make)
                            }
                        }
    
                        for i as integer  = 0 to              AutoParts.Count; i++)
                        {
                            if               not             CbxCategories.Items.Contains(AutoParts(i).Category))
                            {
                                CbxCategories.Items.Add(AutoParts(i).Category)
                            }
                        }
                    }
                }
    
                lblPictureFile.Text = "C:\College Park Auto-Parts10\Generic.png"
                PbxPartImage.Image = Image.FromFile(                                "C:\College Park Auto-Parts10\Generic.png")
    
                Width = PbxPartImage.Right + 40
                Height = PbxPartImage.Bottom + 75
            }
    
            private  sub    StoreItemEditor_Load(object sender, EventArgs e)
            {
                InitializeAutoPart()
            }
        }
    }

11. Return to the Store Item Editor form and double-click the Find Store Item button
12. Implement the event as follows:

    private  sub    BtnFindStoreItem_Click(object sender, EventArgs e)
    {
        if               string.IsNullOrEmpty(TxtPartNumber.Text))
        {
            MsgBox.Regular("You must enter a (valid) number for an auto-part.")
            exit                            sub
        }
    
        bool foundAutoPart = false;
        dim StrFileName as string = "C:\College Park Auto-Parts10\AutoParts.xml"
        dim              XsAutoParts        as         XmlSerializer = new XmlSerializer(typeof(List      (             of           AutoPart)))
    
        if               File.Exists(strFileName))
        {
            using  FsAutoParts      as    FileStream                = new(strFileName, FileMode.Open, FileAccess.Read, FileShare.Read))
            {
                AutoParts = (List      (             of           AutoPart))xsAutoParts.Deserialize(fsAutoParts)
    
                for i as integer  = 0 to              AutoParts.Count; i++)
                {
                    if               AutoParts(i).PartNumber.Equals(CLng(TxtPartNumber.Text)))
                    {
                        foundAutoPart = true;
    
                        CbxMakes.Text = AutoParts(i).Make;
                        CbxModels.Text = AutoParts(i).Model;
                        CbxCategories.Text = AutoParts(i).Category;
                        TxtPartName.Text = AutoParts(i).PartName;
                        CbxYears.Text = AutoParts(i).Year.ToString()
                        TxtUnitPrice.Text = AutoParts(i).UnitPrice,2))
                        PbxPartImage.Image = Image.FromFile(AutoParts(i).PictureFile)
                        lblPictureFile.Text = AutoParts(i).PictureFile;
    
                        exit for
                    }
                }
            }
        }
    
        if               foundAutoPart =               false)
        {
            MsgBox.Regular("There is no auto-part with that number in our records.")
    
            lblPictureFile.Text = "C:\College Park Auto-Parts2\Generic.png"
            PbxPartImage.Image = Image.FromFile("C:\College Park Auto-Parts2\Generic.png")
        }
    
        Width = PbxPartImage.Right + 40
        Height = PbxPartImage.Bottom + 75
    }

13. Return to the Store Item Editor form and double-click the Select Picture button
14. Implement the event as follows:

    private  sub    BtnSelectPicture_Click(object sender, EventArgs e)
    {
        if               ofdPictureFile.ShowDialog() =               DialogResult.OK                         THEN
        {
            lblPictureFile.Text = ofdPictureFile.FileName
            PbxPartImage.Image = Image.FromFile(ofdPictureFile.FileName)
        }
        else
        {
            PbxPartImage.Image = Image.FromFile(                                "C:\College Park Auto-Parts10\Generic.png")
        }
    
        Width = PbxPartImage.Right + 40
        Height = PbxPartImage.Bottom + 75
    }

15. Return to the form and double-click the Makes combo box to generate its Selected Index event
16. Implement the event as follows:

    private  sub    CbxMakes_SelectedIndexChanged(object sender, EventArgs e)
    {
        CbxModels.Items.Clear()
        CbxModels.Text = nothing
    
        for each Part   as   AutoPart  in AutoParts
        {
            if               part.Make =               CbxMakes.Text)
            {
                if               not             CbxModels.Items.Contains(part.Model))
                {
                    CbxModels.Items.Add(part.Model)
                }
            }
        }
    }

17. Return to the form and double-click the New Make button
18. Implement the event as follows:

    private  sub    BtnNewMake_Click(object sender, EventArgs e)
    {
        dim   Editor   as Make  = new Make()
    
        if               editor.ShowDialog() =               DialogResult.OK                         THEN
        {
            if               editor.TxtMake.Text.Length > 0)
            {
                string strMake = editor.TxtMake.Text
    
                if               CbxMakes.Items.Contains(strMake))
                {
                    MsgBox.Regular(strMake + " is already in the list.")
                }
                else
                {
                    CbxMakes.Items.Add(strMake);
                }
    
                CbxMakes.Text = strMake;
            }
        }
    }

19. Return to the form and double-click the New Model button
20. Implement the event as follows:

    private  sub    BtnNewModel_Click(object sender, EventArgs e)
    {
        dim   Editor             as                     Model  = new()
    
        if               editor.ShowDialog() =               DialogResult.OK                         THEN
        {
            if               editor.TxtModel.Text.Length > 0)
            {
                string strModel = editor.TxtModel.Text
    
                if               CbxModels.Items.Contains(strModel))
                {
                    MsgBox.Regular(strModel + " is already in the list.")
                }
                else
                {
                    CbxModels.Items.Add(strModel);
                }
    
                CbxModels.Text = strModel;
            }
        }
    }

21. Return to the form and double-click the New Category button
22. Implement the event as follows:

    private  sub    BtnNewCategory_Click(object sender, EventArgs e)
    {
        var editor = new Category()
    
        if               editor.ShowDialog() =               DialogResult.OK                         THEN
        {
            if               editor.TxtCategory.Text.Length > 0)
            {
                string strCategory = editor.TxtCategory.Text
    
                if               CbxCategories.Items.Contains(strCategory))
                {
                    MsgBox.Regular(strCategory + " is already in the list.")
                }
                else
                {
                    CbxCategories.Items.Add(strCategory);
                }
    
                CbxCategories.Text = strCategory;
            }
        }
    }

23. Return to the Store Item Editor form and double-click the Update Auto-Part button
24. Implement the event as follows:

    private  sub    BtnUpdateAutoPart_Click(object sender, EventArgs e)
    {
        dim StrFileName as string = "C:\College Park Auto-Parts10\AutoParts.xml"
        dim              XsAutoParts        as         XmlSerializer = new XmlSerializer(typeof(List      (             of           AutoPart)))
    
        if               File.Exists(strFileName))
        {
            using  FsAutoParts      as    FileStream                = new FileStream(strFileName,
                                                            FileMode.Open,
                                                            FileAccess.Read,
                                                            FileShare.Read))
            {
                AutoParts = (List      (             of           AutoPart))xsAutoParts.Deserialize(fsAutoParts)
            }
        }
    
        for i as integer  = 0 to              AutoParts.Count; i++)
        {
            if               AutoParts(i).PartNumber.Equals(CLng(TxtPartNumber.Text)))
            {
                AutoParts(i).Year = Convert.ToInt32(CbxYears.Text);
                AutoParts(i).Make = CbxMakes.Text
                AutoParts(i).Model = CbxModels.Text
                AutoParts(i).Category = CbxCategories.Text
                AutoParts(i).PartName = TxtPartName.Text
                AutoParts(i).UnitPrice = Convert.ToDouble(TxtUnitPrice.Text);
                AutoParts(i).PictureFile = lblPictureFile.Text
    
                TextWriter twAutoParts = new StreamWriter(strFileName);
                xsAutoParts.Serialize(twAutoParts, AutoParts);
                twAutoParts.Close()
    
                exit for
            }
        }
    
        InitializeAutoPart()
    }

25. Return to the Store Item Editor form and double-click the Close button
26. Change the document as follows:

    using CollegeParkAutoParts1.Models;
    using System.Xml.Serialization;
    
    namespace CollegeParkAutoParts1
    {
        public partial class StoreItemEditor : Form
        {
            ' This property is used to hold the list of auto-parts of our application.
             * (We didn't have to use a global variable. We could have used local variables.)
            dim AutoParts as List      (             of           AutoPart)  { get; set; } = new List      (             of           AutoPart)
    
            public StoreItemEditor()
            {
                InitializeComponent()
            }
    
            ' This function is used to reset the form.
             * It can be called when necessary.
            private  sub    InitializeAutoPart()
            {
                ' This file is the repository of our database
                dim StrFileName as string = "C:\College Park Auto-Parts10\AutoParts.xml"
                ' We will use XML serialization to manage the records of our database
                dim              XsAutoParts        as         XmlSerializer = new XmlSerializer(typeof(List      (             of           AutoPart)))
    
                CbxYears.Items.Clear()
    
                ' Show the years in the top combo box.
                 * We will consider only the cars made in the last 20 years.
                for CarYear as integer = DateTime.Today.Year + 1   to CarYear >= DateTime.Today.Year - 20 CarYear = CarYear -1)
                {
                    CbxYears.Items.Add(year);
                }
    
                ' Check whether the file that holds the store inventory was created already
                if               File.Exists(strFileName))
                {
                    CbxMakes.Items.Clear()
                    CbxModels.Items.Clear()
                    CbxCategories.Items.Clear()
                    TxtPartName.Text = nothing
                    TxtUnitPrice.Text = nothing
                    TxtPartNumber.Text = nothing
    
                    ' If the inventory file exists, open it
                    using  FsAutoParts      as    FileStream                = new FileStream(strFileName,
                                                                   FileMode.Open,
                                                                   FileAccess.Read,
                                                                   FileShare.Read))
                    {
                        ' Retrieve the list of items from file
                        AutoParts = (List      (             of           AutoPart))xsAutoParts.Deserialize(fsAutoParts)
    
                        ' Display the cars manufacturers in the combo box
                        for i as integer  = 0 to              AutoParts.Count; i++)
                        {
                            ' Make sure the list box doesn't yet have the category being added
                            if               not             CbxMakes.Items.Contains(AutoParts(i).Make))
                            {
                                CbxMakes.Items.Add(AutoParts(i).Make)
                            }
                        }
    
                        ' Display the categories in the box
                        for i as integer  = 0 to              AutoParts.Count; i++)
                        {
                            ' Make sure the list box doesn't yet have the category being added
                            if               not             CbxCategories.Items.Contains(AutoParts(i).Category))
                            {
                                CbxCategories.Items.Add(AutoParts(i).Category)
                            }
                        }
                    }
                }
    
                ' Display the path of the default picture file of the auto part in the top-right label
                lblPictureFile.Text = "C:\College Park Auto-Parts10\Generic.png"
                ' Display the default auto-part image in the picture box
                PbxPartImage.Image = Image.FromFile(                                "C:\College Park Auto-Parts10\Generic.png")
    
                ' Resize the form to show the whole auto-part image
                Width = PbxPartImage.Right + 40
                Height = PbxPartImage.Bottom + 75
            }
    
            private  sub    StoreItemEditor_Load(object sender, EventArgs e)
            {
                InitializeAutoPart()
            }
    
            private  sub    BtnFindStoreItem_Click(object sender, EventArgs e)
            {
                ' When the user clicks the Find Store Item button, make sure the user typed something.
                 * If the Part # text box is empty (meaning the user didn't type a number), ...*/
                if               string.IsNullOrEmpty(TxtPartNumber.Text))
                {
                    ' ... display a message box to the user, ...
                    MsgBox.Regular("You must enter a (valid) number for an auto-part.")
                    ' ... and stop everything
                    exit                            sub
                }
    
                ' This Boolean variable will allow us to know if an auto part was found.
                bool foundAutoPart = false;
                ' Our list of auto-parts is stored in an XML file.
                 * Let's get a reference to that file.
                dim StrFileName as string = "C:\College Park Auto-Parts10\AutoParts.xml"
                ' We process our records through XML serialization.
                 * Create a reference for XML serialization that is initialized with a collection class*/
                dim              XsAutoParts        as         XmlSerializer = new XmlSerializer(typeof(List      (             of           AutoPart)))
    
                ' Before doing anything, check whether a file of auto-parts exists
                if               File.Exists(strFileName))
                {
                    ' Create a stream reference for our file of au-parts
                    using  FsAutoParts      as    FileStream                = new(strFileName, FileMode.Open, FileAccess.Read, FileShare.Read))
                    {
                        ' If the file of auto-parts exists, open that file, get the list of 
                         * auto-parts, and store that list in our collection variable.
                        AutoParts = (List      (             of           AutoPart))xsAutoParts.Deserialize(fsAutoParts)
    
                        ' Now that the list of auto-parts exists, navigate to each item of the list
                        for i as integer  = 0 to              AutoParts.Count; i++)
                        {
                            ' When you reach an auto-part, check whether its part number is 
                             * the same as the number the user typed.*/
                            if               AutoParts(i).PartNumber.Equals(CLng(TxtPartNumber.Text)))
                            {
                                ' If the auto-part was found, make a not by updating our Boolean variable
                                foundAutoPart = true;
    
                                CbxMakes.Text = AutoParts(i).Make;
                                CbxModels.Text = AutoParts(i).Model;
                                CbxCategories.Text = AutoParts(i).Category;
                                TxtPartName.Text = AutoParts(i).PartName;
                                CbxYears.Text = AutoParts(i).Year.ToString()
                                TxtUnitPrice.Text = AutoParts(i).UnitPrice,2))
                                PbxPartImage.Image = Image.FromFile(AutoParts(i).PictureFile)
                                lblPictureFile.Text = AutoParts(i).PictureFile;
                                ' Since an auto-part was found 
                                 * and its values have been displayed, stop searching.
                                exit for
                            }
                        }
                    }
                }
    
                ' Check the value of our Boolean variable. If that value is false, ...
                if               foundAutoPart =               false)
                {
                    ' ... it means no auto-part was found. Display a message box to the user
                    MsgBox.Regular("There is no auto-part with that number in our records.")
    
                    lblPictureFile.Text = "C:\College Park Auto-Parts2\Generic.png"
                    PbxPartImage.Image = Image.FromFile("C:\College Park Auto-Parts2\Generic.png")
                }
    
                Width = PbxPartImage.Right + 40
                Height = PbxPartImage.Bottom + 75
            }
    
            private  sub    BtnSelectPicture_Click(object sender, EventArgs e)
            {
                ' When the user clicks the Select Picture button, display the Open File Dialog box
                if               ofdPictureFile.ShowDialog() =               DialogResult.OK                         THEN
                {
                    ' If the user selects a picture and clicks OK, ...
                     * display the path of the picture file in the top-right label, ...*/
                    lblPictureFile.Text = ofdPictureFile.FileName
                    ' ... display the auto picture in the picture box
                    PbxPartImage.Image = Image.FromFile(ofdPictureFile.FileName)
                }
                else
                {
                    ' If the user didn't select a valid picture, display the default one
                    PbxPartImage.Image = Image.FromFile(                                "C:\College Park Auto-Parts10\Generic.png")
                }
    
                ' Resize the form to show the whole auto-part image
                Width = PbxPartImage.Right + 40
                Height = PbxPartImage.Bottom + 75
            }
    
            private  sub    CbxMakes_SelectedIndexChanged(object sender, EventArgs e)
            {
                CbxModels.Items.Clear()
                CbxModels.Text = nothing
    
                for each Part   as   AutoPart  in AutoParts
                {
                    if               part.Make =               CbxMakes.Text)
                    {
                        if               not             CbxModels.Items.Contains(part.Model))
                        {
                            CbxModels.Items.Add(part.Model)
                        }
                    }
                }
            }
    
            private  sub    BtnNewMake_Click(object sender, EventArgs e)
            {
                dim   Editor   as Make  = new Make()
    
                if               editor.ShowDialog() =               DialogResult.OK                         THEN
                {
                    if               editor.TxtMake.Text.Length > 0)
                    {
                        string strMake = editor.TxtMake.Text
    
                        if               CbxMakes.Items.Contains(strMake))
                        {
                            MsgBox.Regular(strMake + " is already in the list.")
                        }
                        else
                        {
                            CbxMakes.Items.Add(strMake);
                        }
    
                        CbxMakes.Text = strMake;
                    }
                }
            }
    
            private  sub    BtnNewModel_Click(object sender, EventArgs e)
            {
                dim   Editor             as                     Model  = new()
    
                if               editor.ShowDialog() =               DialogResult.OK                         THEN
                {
                    if               editor.TxtModel.Text.Length > 0)
                    {
                        string strModel = editor.TxtModel.Text
    
                        if               CbxModels.Items.Contains(strModel))
                        {
                            MsgBox.Regular(strModel + " is already in the list.")
                        }
                        else
                        {
                            CbxModels.Items.Add(strModel);
                        }
    
                        CbxModels.Text = strModel;
                    }
                }
            }
    
            private  sub    BtnNewCategory_Click(object sender, EventArgs e)
            {
                var editor = new Category()
    
                if               editor.ShowDialog() =               DialogResult.OK                         THEN
                {
                    if               editor.TxtCategory.Text.Length > 0)
                    {
                        string strCategory = editor.TxtCategory.Text
    
                        if               CbxCategories.Items.Contains(strCategory))
                        {
                            MsgBox.Regular(strCategory + " is already in the list.")
                        }
                        else
                        {
                            CbxCategories.Items.Add(strCategory);
                        }
    
                        CbxCategories.Text = strCategory;
                    }
                }
            }
    
            private  sub    BtnUpdateAutoPart_Click(object sender, EventArgs e)
            {
                dim StrFileName as string = "C:\College Park Auto-Parts10\AutoParts.xml"
                dim              XsAutoParts        as         XmlSerializer = new XmlSerializer(typeof(List      (             of           AutoPart)))
    
                if               File.Exists(strFileName))
                {
                    using  FsAutoParts      as    FileStream                = new FileStream(strFileName,
                                                                    FileMode.Open,
                                                                    FileAccess.Read,
                                                                    FileShare.Read))
                    {
                        AutoParts = (List      (             of           AutoPart))xsAutoParts.Deserialize(fsAutoParts)
                    }
                }
    
                for i as integer  = 0 to              AutoParts.Count; i++)
                {
                    if               AutoParts(i).PartNumber.Equals(CLng(TxtPartNumber.Text)))
                    {
                        AutoParts(i).Year = Convert.ToInt32(CbxYears.Text);
                        AutoParts(i).Make = CbxMakes.Text
                        AutoParts(i).Model = CbxModels.Text
                        AutoParts(i).Category = CbxCategories.Text
                        AutoParts(i).PartName = TxtPartName.Text
                        AutoParts(i).UnitPrice = Convert.ToDouble(TxtUnitPrice.Text);
                        AutoParts(i).PictureFile = lblPictureFile.Text
    
                        TextWriter twAutoParts = new StreamWriter(strFileName);
                        xsAutoParts.Serialize(twAutoParts, AutoParts);
                        twAutoParts.Close()
    
                        exit for
                    }
                }
    
                InitializeAutoPart()
            }
    
            private  sub    BtnClose_Click(object sender, EventArgs e)
            {
                Close()
            }
        }
    }

27. Display the Store Inventory form
28. Add an Auto Part Editor button as follows:

    

    Control		(Name)	Text
    Button		BtnUpdateAutoPart	Update Auto Part...

29. Double-click the Auto Part Details button
30. Implement the event as follows:

    private  sub    BtnAutoPartEditor_Click(object sender, EventArgs e)
    {
        StoreItemEditor editor = new StoreItemEditor()
    
        editor.ShowDialog()
    
        InitializeAutoParts()
    }

31. To execute, on the main menu, click Debug and click Start Without Debugging:

    

32. Click the Auto Part Details button:

    

33. In the Part # text box, type 155975
34. Click the Find Store Item button:

    

35. Change the following values:

    Year:       2025
    Model:      Envista
    Part Name:  Multi-Part Front and Rear Wheel Bearing Assembly
    Unit Price: 122.86

36. Close the forms and return to your programming environment

Store Item Deletion

In a typical database application, when an item is not necessary anymore, its records can be removed. To support this operation, we will create an appropriate form.

Practical Learning: Delting a Store Item

1. To add a new form, on the main menu, click Project -> Add Form (Windows Forms)...
2. Type the Name as StoreItemDelete
3. Click Add
4. Click an unoccupied area of the form and, in the Properties window, change the following characteristics:
   Text: College Park Auto-Parts - Store Item Deletion
   MaximizeBox: False
   StartPosition: CenterScreen
5. Resize the Store Item Delete form to have approximately the same size as the Store Item Details form
6. Select and copy all controls on the Store Item Details form
7. Paste the copied controls to the Store Item Delete form
8. Complete the design of the form as follows:

   

   Control		(Name)	Text
   Button		BtnDeleteAutoPart	Delete Auto Part...
   Button		BtnClose	Close

9. Double-click the Find Store Item button
10. Implement the event as follows:

    using CollegeParkAutoParts1.Models;
    using System.Xml.Serialization;
    
    namespace CollegeParkAutoParts1
    {
        public partial class StoreItemDelete : Form
        {
            dim AutoParts as List      (             of           AutoPart)  { get; set; } = new List      (             of           AutoPart)
    
            public StoreItemDelete()
            {
                InitializeComponent()
            }
    
            private  sub    BtnFindStoreItem_Click(object sender, EventArgs e)
            {
                ' When the user clicks the Find Store Item button, make sure the user typed something.
                 * If the Part # text box is empty (meaning the user didn't type a number), ...*/
                if               string.IsNullOrEmpty(TxtPartNumber.Text))
                {
                    ' ... display a message box to the user, ...
                    MsgBox.Regular("You must enter a (valid) number for an auto-part.")
                    ' ... and stop everything
                    exit                            sub
                }
    
                ' This Boolean variable will allow us to know if an auto part was found.
                bool foundAutoPart = false;
                ' Our list of auto-parts is stored in an XML file.
                 * Let's get a reference to that file.
                dim StrFileName as string = "C:\College Park Auto-Parts10\AutoParts.xml"
                ' We process our records through XML serialization.
                 * Create a reference for XML serialization that is initialized with a collection class*/
                dim              XsAutoParts        as         XmlSerializer = new XmlSerializer(typeof(List      (             of           AutoPart)))
    
                ' Before doing anything, check whether a file of auto-parts exists
                if               File.Exists(strFileName))
                {
                    ' Create a stream reference for our file of au-parts
                    using  FsAutoParts      as    FileStream                = new(strFileName, FileMode.Open, FileAccess.Read, FileShare.Read))
                    {
                        ' If the file of auto-parts exists, open that file, get the list of 
                         * auto-parts, and store that list in our collection variable.
                        AutoParts = (List      (             of           AutoPart))xsAutoParts.Deserialize(fsAutoParts)
    
                        ' Now that the list of auto-parts exists, navigate to each item of the list
                        for i as integer  = 0 to              AutoParts.Count; i++)
                        {
                            ' When you reach an auto-part, check whether its part number is 
                             * the same as the number the user typed.*/
                            if               AutoParts(i).PartNumber.Equals(CLng(TxtPartNumber.Text)))
                            {
                                ' If the auto-part was found, make a not by updating our Boolean variable
                                foundAutoPart = true;
    
                                ' Get the values of the auto-part and display them in the Windows controls
                                TxtMake.Text = AutoParts(i).Make;
                                TxtModel.Text = AutoParts(i).Model;
                                TxtCategory.Text = AutoParts(i).Category;
                                TxtPartName.Text = AutoParts(i).PartName;
                                TxtYear.Text = AutoParts(i).Year.ToString()
                                TxtUnitPrice.Text = AutoParts(i).UnitPrice,2))
                                PbxPartImage.Image = Image.FromFile(AutoParts(i).PictureFile)
                                lblPictureFile.Text = AutoParts(i).PictureFile;
                                ' Since an auto-part was found 
                                 * and its values have been displayed, stop searching.
                                exit for
                            }
                        }
                    }
                }
    
                ' Check the value of our Boolean variable. If that value is false, ...
                if               foundAutoPart =               false)
                {
                    ' ... it means no auto-part was found. Display a message box to the user
                    MsgBox.Regular("There is no auto-part with that number in our records.")
    
                    lblPictureFile.Text = "C:\College Park Auto-Parts10\Generic.png"
                    PbxPartImage.Image = Image.FromFile(                                "C:\College Park Auto-Parts10\Generic.png")
                }
    
                Width = PbxPartImage.Right + 40
                Height = PbxPartImage.Bottom + 75
            }
        }
    }

11. Return to the form and double-click the Delete Auto Part button
12. Define the event as follows:

    private  sub    BtnDeleteAutoPart_Click(object sender, EventArgs e)
    {
        XmlSerializer xsAutoParts = new(typeof(List      (             of           AutoPart)))
        dim StrFileName as string = "C:\College Park Auto-Parts10\AutoParts.xml"
    
        if               File.Exists(strFileName))
        {
            using FileStream fsAutoParts = new(strFileName, FileMode.Open,
                                               FileAccess.Read, FileShare.Read);
            AutoParts = (List      (             of           AutoPart))xsAutoParts.Deserialize(fsAutoParts)
        }
    
        for i as integer  = 0 to              AutoParts.Count; i++)
        {
            if               AutoParts(i).PartNumber.Equals(CLng(TxtPartNumber.Text)))
            {
                AutoParts.Remove(AutoParts(i));
    
                TextWriter twAutoParts = new StreamWriter(strFileName);
                xsAutoParts.Serialize(twAutoParts, AutoParts);
                twAutoParts.Close()
    
                exit for
            }
        }
    
        InitializeAutoPart()
    }

13. Return to the form and double-click the Close button
14. Change the document as follows:

    private  sub    BtnClose_Click(object sender, EventArgs e)
    {
        Close()
    }

15. Display the Store Inventory form
16. Add an Auto Part Delete and a Close buttons as follows:

    

    Control		(Name)	Text
    Label		BtnDeleteAutoPart	Delete Auto-Part
    Button		BtnClose	Close

17. Double-click the Delete Auto-Part button
18. Define the event as follows:

    private  sub    BtnDeleteAutoPart_Click(object sender, EventArgs e)
    {
        StoreItemDelete delete = new StoreItemDelete()
    
        delete.ShowDialog()
    
        InitializeAutoParts()
    }

19. Return to the form and double-click the Close button
20. Change the document as follows:

    using CollegeParkAutoParts1.Models;
    using System.Xml.Serialization;
    
    namespace CollegeParkAutoParts1
    {
        public partial class StoreInventory : Form
        {
            ' We will need a list of auto-parts.
             * For demonstration purpose, we are creating the list as a property
             * (but a global list is not necessary; we could have used local list variables).*/
            public dim AutoParts as List      (             of           AutoPart)  { get; set; } = new List      (             of           AutoPart)
    
            public StoreInventory()
            {
                InitializeComponent()
            }
    
            ' This function is used to reset the form
            void InitializeAutoParts()
            {
                ' When the form must be reset, removes all nodes from the tree view
                tvwAutoParts.Nodes.Clear()
                ' Create the root node of the tree view
                TreeNode nodRoot = tvwAutoParts.Nodes.Add("College Park Auto-Parts",
                                                          "College Park Auto-Parts", 0, 1);
                ' Add the cars years to the tree view.
                 * Our application will deal only with the cars in the last 21 years.
                for CarYear as integers = DateTime.Today.Year + 1; years >= DateTime.Today.Year - 20; years--)
                {
                    nodRoot.Nodes.Add(years.ToString(), years.ToString(), 2, 3);
                }
    
                ' Select the root node
                tvwAutoParts.SelectedNode = nodRoot;
                ' Expand the root node
                tvwAutoParts.ExpandAll()
    
                ' AutoParts = new List      (             of           AutoPart)
    
                ' This is the file that holds the list of auto parts
                dim StrFileName as string = "C:\College Park Auto-Parts10\AutoParts.xml"
                ' Create an XmlSerializer object to retrieve the list of auto parts from file
                XmlSerializer xsAutoParts = new(typeof(List      (             of           AutoPart)))
    
                if               File.Exists(strFileName))
                {
                    ' If the inventory file exists, open it
                    using  FsAutoParts      as    FileStream                = new FileStream(strFileName,
                                                                    FileMode.Open,
                                                                    FileAccess.Read,
                                                                    FileShare.Read))
                    {
                        ' Retrieve the list of items from file
                        AutoParts = (List      (             of           AutoPart))xsAutoParts.Deserialize(fsAutoParts)
    
                        ' Show the makes nodes
                        foreach (TreeNode nodYear in nodRoot.Nodes)
                        {
                            ' Start a new list of car manufacturers
                            List<string> lstMakes = new List<string>()
    
                            ' Visit each item from the AutoParts list
                            for each Part   as   AutoPart  in AutoParts
                            {
                                ' When you get to an auto part with the same year as the year of the node, ...
                                if               nodYear.Text =               part.Year.ToString())
                                {
                                    ' ... add the make to the list of makes
                                    if               not             lstMakes.Contains(part.Make!))
                                    {
                                        lstMakes.Add(part.Make)
                                    }
                                }
                            }
    
                            ' For the current year node in the tree view, and from the list of auto-parts, ...
                            foreach (string strMake in lstMakes)
                            {
                                ' ... add the make as a node to the tree view
                                nodYear.Nodes.Add(strMake, strMake, 4, 5);
                            }
                        }
    
                        ' Show the models that correspond to the makes and years nodes
                        foreach (TreeNode nodYear in nodRoot.Nodes)
                        {
                            foreach (TreeNode nodMake in nodYear.Nodes)
                            {
                                List<string> lstModels = new List<string>()
    
                                for each Part   as   AutoPart  in AutoParts
                                {
                                    if               (nodYear.Text =               part.Year.ToString()) &
                                        (nodMake.Text =               part.Make))
                                    {
                                        if               not             lstModels.Contains(part.Model!))
                                            lstModels.Add(part.Model)
                                    }
                                }
    
                                foreach (string strModel in lstModels)
                                    nodMake.Nodes.Add(strModel, strModel, 6, 7);
                            }
                        }
    
                        ' Show the categories of items
                        foreach (TreeNode nodYear in nodRoot.Nodes)
                        {
                            foreach (TreeNode nodMake in nodYear.Nodes)
                            {
                                foreach (TreeNode nodModel in nodMake.Nodes)
                                {
                                    List<string> lstCategories = new List<string>()
    
                                    for each Part   as   AutoPart  in AutoParts
                                    {
    
                                        if               (nodYear.Text =               part.Year.ToString()) &
                                            (nodMake.Text =               part.Make) &
                                            (nodModel.Text =               part.Model))
                                        {
                                            if               not             lstCategories.Contains(part.Category!))
                                                lstCategories.Add(part.Category)
                                        }
                                    }
    
                                    foreach (string strCategory in lstCategories)
                                        nodModel.Nodes.Add(strCategory, strCategory, 8, 9);
                                }
                            }
                        }
                    }
                }
    
                ' Reset the form
                LvwSelectedParts.Items.Clear()
                LvwAvailableParts.Items.Clear()
                TxtTaxRate.Text = nothing
                TxtPartName.Text = nothing
                TxtQuantity.Text = nothing
                TxtSubTotal.Text = nothing
                TxtUnitPrice.Text = nothing
                TxtTaxAmount.Text = nothing
                TxtOrderTotal.Text = nothing
                TxtPartNumber.Text = nothing
                TxtSelectedPartsTotal.Text = nothing
                PbxPartImage.Image = Image.FromFile(                                "C:\College Park Auto-Parts10\Generic.png")
    
                Width = PbxPartImage.Right + 40
            }
    
            private  sub    StoreInventory_Load(object sender, EventArgs e)
            {
                InitializeAutoParts()
            }
    
            private  sub    LvwAvailableParts_ItemSelectionChanged(object sender, ListViewItemSelectionChangedEventArgs e)
            {
                bool pictureFound = false;
                dim StrFileName as string = "C:\College Park Auto-Parts10\AutoParts.xml"
                dim              XsAutoParts        as         XmlSerializer = new XmlSerializer(typeof(List      (             of           AutoPart)))
    
                if               File.Exists(strFileName))
                {
                    using  FsAutoParts      as    FileStream                = new FileStream(strFileName,
                                                                   FileMode.Open,
                                                                   FileAccess.Read,
                                                                   FileShare.Read))
                    {
                        AutoParts = (List      (             of           AutoPart))xsAutoParts.Deserialize(fsAutoParts)
    
                        for each Part   as   AutoPart  in AutoParts
                        {
                            if               part.PartNumber =               CLng(e.Item.SubItems(0).Text))
                            {
                                pictureFound = true;
                                PbxPartImage.Image = Image.FromFile(part.PictureFile)
                                exit for
                            }
                        }
                    }
                }
    
                if               pictureFound =               false)
                {
                    PbxPartImage.Image = Image.FromFile(                                "C:\College Park Auto-Parts10\Generic.png")
                }
    
                Width = PbxPartImage.Right + 40
                Height = PbxPartImage.Bottom + 75
            }
    
            private  sub    LvwAvailableParts_DoubleClick(object sender, EventArgs e)
            {
                ListViewItem LviAutoPart = LvwAvailableParts.SelectedItems(0)
    
                if               (LvwAvailableParts.SelectedItems.Count =               0) OR
                    (LvwAvailableParts.SelectedItems.Count > 1))
                    exit                            sub
    
                TxtPartNumber.Text = LviAutoPart.Text
                TxtPartName.Text = LviAutoPart.SubItems(1).Text
                TxtUnitPrice.Text = LviAutoPart.SubItems(2).Text
    
                TxtQuantity.Text = "1"
                TxtSubTotal.Text = LviAutoPart.SubItems(2).Text
    
                TxtQuantity.Focus()
            }
    
            private  sub    TxtUnitPrice_Leave(object sender, EventArgs e)
            {
                double subTotal;
                double unitPrice = 0D;
                double quantity = 0.00d;
    
                try
                {
                    unitPrice = cdbl(TxtUnitPrice.Text);
                }
                catch Fex                     as         FormatException
                {
                    MsgBox.Regular("Invalid Unit Price!")
                }
    
                try
                {
                    quantity = cint(TxtQuantity.Text);
                }
                catch Fex                     as         FormatException
                {
                    MsgBox.Regular("Invalid Quandtity!")
                }
    
                subTotal = unitPrice * quantity;
                TxtSubTotal.Text = subTotal,2))
            }
    
            private  sub    TxtPartNumber_Leave(object sender, EventArgs e)
            {
                bool found = false;
    
                for each Part   as   AutoPart  in AutoParts
                {
                    if               part.PartNumber =               CLng(TxtPartNumber.Text))
                    {
                        TxtPartName.Text = part.PartName;
                        TxtUnitPrice.Text = part.UnitPrice,2))
    
                        if               string.IsNullOrEmpty(TxtQuantity.Text))
                            TxtQuantity.Text = "1"
    
                        TxtSubTotal.Text = part.UnitPrice,2))
    
                        TxtQuantity.Focus()
    
                        found = true;
                        exit for
                    }
                }
    
                if               found =               false)
                {
                    TxtPartName.Text = ""
                    TxtUnitPrice.Text = "0.00"
                    TxtQuantity.Text = "0"
                    TxtSubTotal.Text = "0.00"
    
                    MsgBox.Regular("There is no part with that number.")
                }
            }
    
            private  sub    CalculateOrder()
            {
                double partsTotal = 0.00D;
                double taxRate = 0.00D;
                double taxAmount, orderTotal;
    
                if               string.IsNullOrEmpty(TxtTaxRate.Text))
                    TxtTaxRate.Text = "7.25"
    
                foreach (ListViewItem lvi in LvwSelectedParts.Items)
                {
                    ListViewItem.ListViewSubItem SubItem = lvi.SubItems(4)
                    partsTotal += cdbl(SubItem.Text);
                }
    
                try
                {
                    taxRate = cdbl(TxtTaxRate.Text) / 100;
                }
                catch Fex                     as         FormatException
                {
                    MsgBox.Regular("Invalid Tax Rate")
                }
    
                taxAmount = partsTotal * taxRate;
                orderTotal = partsTotal + taxAmount;
    
                TxtSelectedPartsTotal.Text = partsTotal,2))
                TxtTaxAmount.Text = taxAmount,2))
                TxtOrderTotal.Text = orderTotal,2))
            }
    
            private  sub    BtnAdd_Click(object sender, EventArgs e)
            {
                if               string.IsNullOrEmpty(TxtPartNumber.Text))
                {
                    MsgBox.Regular("There is no part to be added to the order.")
                    exit                            sub
                }
    
                for each Part   as   AutoPart  in AutoParts
                {
                    if               part.PartNumber =               CLng(TxtPartNumber.Text))
                    {
                        ListViewItem lviSelectedPart = new ListViewItem(part.PartNumber.ToString());
    
                        lviSelectedPart.SubItems.Add(part.PartName);
                        lviSelectedPart.SubItems.Add(part.UnitPrice.ToString());
                        lviSelectedPart.SubItems.Add(TxtQuantity.Text);
                        lviSelectedPart.SubItems.Add(TxtSubTotal.Text);
                        LvwSelectedParts.Items.Add(lviSelectedPart);
                    }
                }
    
                CalculateOrder()
            }
    
            private  sub    LvwSelectedParts_DoubleClick(object sender, EventArgs e)
            {
                ListViewItem lviSelectedPart = LvwSelectedParts.SelectedItems(0)
    
                if               (LvwSelectedParts.SelectedItems.Count =               0) OR
                    (LvwSelectedParts.SelectedItems.Count > 1))
                    exit                            sub
    
                TxtPartNumber.Text = lviSelectedPart.Text
                TxtPartName.Text = lviSelectedPart.SubItems(1).Text
                TxtUnitPrice.Text = lviSelectedPart.SubItems(2).Text
                TxtQuantity.Text = lviSelectedPart.SubItems(3).Text
                TxtSubTotal.Text = lviSelectedPart.SubItems(4).Text
    
                LvwSelectedParts.Items.Remove(lviSelectedPart);
                CalculateOrder()
            }
    
            private  sub    tvwAutoParts_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
            {
                TreeNode nodClicked = e.Node!;
    
                if               nodClicked.Level =               4)
                    LvwAvailableParts.Items.Clear()
    
                try
                {
                    for each Part   as   AutoPart  in AutoParts
                    {
                        if               (part.Category =               nodClicked.Text) andalso
                            (part.Model =               nodClicked.Parent!.Text) andalso
                            (part.Make =               nodClicked.Parent.Parent!.Text) andalso
                            (part.Year.ToString() =               nodClicked.Parent.Parent.Parent!.Text))
                        {
                            ListViewItem LviAutoPart = new ListViewItem(part.PartNumber.ToString());
    
                            LviAutoPart.SubItems.Add(part.PartName);
                            LviAutoPart.SubItems.Add(part.UnitPrice,2)));
                            LvwAvailableParts.Items.Add(LviAutoPart);
                        }
                    }
                }
                catch (NullReferenceException)
                {
                }
            }
    
            private  sub    BtnNewAutoPart_Click(object sender, EventArgs e)
            {
                StoreItemNew @new = new StoreItemNew()
    
                @new.ShowDialog()
    
                InitializeAutoParts()
            }
    
            private  sub    BtnAutoPartDetails_Click(object sender, EventArgs e)
            {
                StoreItemDetails details = new StoreItemDetails()
    
                details.Show()
            }
    
            private  sub    BtnAutoPartEditor_Click(object sender, EventArgs e)
            {
                StoreItemEditor editor = new StoreItemEditor()
    
                editor.ShowDialog()
    
                InitializeAutoParts()
            }
    
            private  sub    BtnDeleteAutoPart_Click(object sender, EventArgs e)
            {
                StoreItemDelete delete = new StoreItemDelete()
    
                delete.ShowDialog()
    
                InitializeAutoParts()
            }
    
            private  sub    BtnClose_Click(object sender, EventArgs e)
            {
                Close()
            }
        }
    }

21. To execute, on the main menu, click Debug and click Start Without Debugging:

    

22. Click the Delete Auto Part button:

    

23. In the Part # text box, type 928374
24. Click the Find Store Item button:

    

25. Click the Delete Auto Part button
26. On the Auto Part Deletion form, click the Close button
27. On the main form of the application, click the Close button

Example Application: Stellar Water Point

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