File-Based Applications: Bethesda Car Rental

	File-Based Applications: Bethesda Car Rental

Introduction

Imagine you get a contract or an assignment to create an application used to process business transactions for a car rental company. In this case, we will call it Bethesda Car Rental. If you decide to use then .NET Framework to develop the application, you have various options. You can use file processing for a file-based database. You can proceed with XML to save company files in a format that can be accessed by different types of applications, including the World Wide Web. Or you can create a formal database using Microsoft SQL Server, Borland/Corel Paradox, or MS Access, etc. In this example, we will create our application using regular files.

This application assumes that you have some knowledge or a basic understanding of file processing and serialization as it is featured in the .NET Framework but we will be as clear as possible with this exercise and its different parts.

Practical Learning: Processing Cars

Start Microsoft Visual Basic .NET or Visual Studio .NET and create a new Windows Application named BCR2
In the Solution Explorer, right-click Form1 and click Rename
Type Switchboard.vb and press Enter twice twice to display the first form

Employees

An employee will be anybody who works for this company, whether the person is part of the management or is one of those who process transactions. In a formal company, various pieces of information are provided for each employee. In our example, we will get only the strict minimum.

Practical Learning: Creating Employees

To add a new form to the application, on the main menu, click Project -> Add Windows Form...
Set the Name to Employees and press Enter
From the Toolbox, add a ListView to the form

While the new list view is still selected, in the Properties window, click the ellipsis button of the Columns field and create the columns as follows:

(Name)	Text	Width
colFirstName	First Name	80
colLastName	Last Name	80
colTitle	Title	200
colGender	Gender	80

Design the form as follows:

Control	Text	Name	Other Properties
ListView		lvwEmployees	Anchor: Top, Bottom, Left, Right FullRowSelect: True GridLines: True View: Details
Button	New Employee	btnNewEmployee
Button	Close	btnClose

To add another form to the application, on the main menu, click Project . Add Windows Forms...
Set the Name to NewEmployee and press Enter

Design the form as follows:

Control	Text	Name	Properties
Label	First Name:
TextBox		txtFirstName	Modifiers: public
Label	Last Name:
TextBox		txtLastName	Modifiers: public
Label	Title:
TextBox		txtTitle	Modifiers: public
Label	Gender:
ComboBox		cboGenders	Modifiers: public Items: Female Male Unknown
Button	Add	btnAdd	DialogResult: OK
Button	Cancel	btnCancel	DialogResult: Cancel
Form			AcceptButton: btnAdd CancelButton: btnClose FormBorderStyle: FixedDialog MaximizeBox: False MinimizeBox: False ShowInTaskbar: False

To add a new class to the project, on the main menu, click Project -> Add Class...
Set the Class Name to Employee and click Open

Change the Employee.vb file as follows:

<Serializable()> Public NotInheritable Class Employee
    Public FirstName As String
    Public LastName As String
    Public Title As String
    Public Gender As String

    Public Sub New()
        FirstName = "Unknown"
        LastName = "Unknown"
        Title = "N/A"
        Gender = "Unknown"
    End Sub

    Public Sub New(ByVal fname As String, ByVal lname As String, _
                   ByVal title As String, ByVal sex As String)
        FirstName = fname
        LastName = lname
        title = title
        Gender = sex
    End Sub
End Class

In the Solution Explorer, right-click the References node and click Add Reference...
In the .NET property page of the Add Reference dialog box, select System.Runtime.Serialization.Formatters.Soap and click Select
Click OK
Return to the Employees form. Right-click it and click View Code

In the top section of the file, type:

Imports System.IO
Imports System.Runtime.Serialization.Formatters.Soap

Public Class Employees
    Inherits System.Windows.Forms.Form

    Private lstEmployees As ArrayList

Just before the End Class line, create a sub procedure as follows:

Private Sub ShowEmployees()
        Dim bcrSoap As SoapFormatter = New SoapFormatter
        Dim strFilename As String = "Employees.bcr"

        If File.Exists(strFilename) Then
Dim bcrStream As FileStream = New FileStream(strFilename, FileMode.Open, FileAccess.Read, FileShare.Read)
            Dim lstEmpl As ArrayList = bcrSoap.Deserialize(bcrStream)
            bcrStream.Close()

            Dim empl As Employee

            lvwEmployees.Items.Clear()

            For i As Integer = 0 To lstEmpl.Count - 1
                empl = lstEmpl(i)
                Dim lviEmployee As ListViewItem = New ListViewItem(empl.FirstName)
                lviEmployee.Font = New Font("Georgia", 8, FontStyle.Bold)

                If i Mod 2 = 0 Then
                    lviEmployee.BackColor = Color.Blue
                    lviEmployee.ForeColor = Color.White
                Else
                    lviEmployee.BackColor = Color.LightBlue
                    lviEmployee.ForeColor = Color.Blue
                End If

                lviEmployee.SubItems.Add(empl.LastName)
                lviEmployee.SubItems.Add(empl.Title)
                lviEmployee.SubItems.Add(empl.Gender)
                lvwEmployees.Items.Add(lviEmployee)
            Next
        End If
End Sub

In the Class Name combo box, select (Employees Events)

In the Method Name combo box, select Load and implement the event as follows:

Private Sub Employees_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
        lstEmployees = New ArrayList
        Dim bcrSoap As SoapFormatter = New SoapFormatter
        Dim strFilename As String = "Employees.bcr"

        If File.Exists(strFilename) Then
Dim bcrStream As FileStream = New FileStream(strFilename, FileMode.Open, FileAccess.Read, FileShare.Read)
            lstEmployees = bcrSoap.Deserialize(bcrStream)
            bcrStream.Close()
        End If

        ShowEmployees()
End Sub

In the Class Name combo box, select btnNewEmployee

In the Method Name combo box, select Click and implement the event as follows:

Private Sub btnNewEmployee_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnNewEmployee.Click
        Dim dlgEmpl As NewEmployee = New NewEmployee

        If dlgEmpl.ShowDialog() = DialogResult.OK Then
            If dlgEmpl.txtLastName.Text = "" Then
                MsgBox("You must provide at least a last name to create a new employee")
                Exit Sub
            Else
                Dim strFilename As String = "Employees.bcr"
                Dim empl As Employee = New Employee

                empl.FirstName = dlgEmpl.txtFirstName.Text
                empl.LastName = dlgEmpl.txtLastName.Text
                empl.Title = dlgEmpl.txtTitle.Text
                empl.Gender = dlgEmpl.cboGenders.Text

                lstEmployees.Add(empl)

Dim bcrStream As FileStream = New FileStream(strFilename, FileMode.OpenOrCreate, FileAccess.Write, FileShare.Write)
                Dim bcrSoap As SoapFormatter = New SoapFormatter
                bcrSoap.Serialize(bcrStream, lstEmployees)
                bcrStream.Close()

                ShowEmployees()
            End If
        End If
End Sub

In the Class Name combo box, select btnClose

In the Method Name combo box, select Click and implement the event as follows:

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

Display the Switchboard form
Add a Button to the form and change its properties as follows:
(Name): btnEmployees
Text: Employees
Double-click the Employees button to generate its Click event

Implement the event as follows:

Private Sub btnEmployees_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEmployees.Click
        Dim frmEmpl As Employees = New Employees

        frmEmpl.Show()
End Sub

Execute the application

Create a few employees as follows:

First Name	Last Name	Title	Gender
Patricia	Katts	Store Manager	Female
Henry	Larson	Sales Representative	Male
Gertrude	Palau	Sales Representative	Female
Helene	Sandt	Intern	Female
Melanie	Karron	Sales Representative	Unknown
Ernest	Chisen	Sales Manager	Male
Melissa	Roberts	Administrative Assistant	Female

Close the forms and return to your programming environment


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