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 C++ .NET or Visual Studio .NET and create a new Windows Forms Application named BCR2

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 New Item...
In the Templates list of the Add New Item dialog box, click Windows Forms (.NET)
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 New Item...
In the Templates list of the Add New Item dialog box, click Windows Forms (.NET)
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...
In the Templates list, click Generic C++ Class and click Open
Set the Class Name to Employee and click Finish
In the Solution Explorer, double-click Employee.h

Change the Employee.h file as follows:

#pragma once

using namespace System;

[Serializable]
public __gc class Employee
{
public:
	String *FirstName;
	String *LastName;
	String *Title;
	String *Gender;

public:
	Employee(void);
	Employee(String *fname, String *lname,
			 String *title, String *sex);
	~Employee(void);
};

Change the Employee.cpp file as follows:

#include "StdAfx.h"
#include ".\employee.h"
#using <mscorlib.dll>

Employee::Employee(void)
{
	FirstName = S"Unknown";
	LastName  = S"Unknown";
	Title     = S"N/A";
	Gender    = S"Unknown";
}

Employee::Employee(String *fname, String *lname,
		   String *title, String *sex)
{
	FirstName = fname;
	LastName  = lname;
	Title     = title;
	Gender    = sex;
}

Employee::~Employee(void)
{
}

In the Class View, expand BCR2 and BCR2
Right-click Employees -> Add -> Add Function...
Set the Return Type to void
Set the Function Name to ShowEmployees and its Access to private
Click Finish
Return to the Employees form and double-click an empty area of its body to generate its Load event
Return to the Employees form and double-click its New Employee button
Return to the Employees form and double-click its Close button

Change the file as follows:

#pragma once

#using <System.Runtime.Serialization.Formatters.Soap.dll>

#include "NewEmployee.h"
#include "Employee.h"

using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
using namespace System::Data;
using namespace System::Drawing;
using namespace System::IO;
using namespace System::Runtime::Serialization::Formatters::Soap;

namespace BCR2
{
	. . . 
	
	public __gc class Employees : public System::Windows::Forms::Form
	{
	public: 
		. . .

	private:
		/// <summary>
		/// Required designer variable.
		/// </summary>
		System::ComponentModel::Container* components;
		ArrayList *lstEmployees;

		/// <summary>
		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// </summary>
		void InitializeComponent(void)
		{
			. . . 
		}		
	
void ShowEmployees(void)
{
	 SoapFormatter *bcrSoap = new SoapFormatter();
	 String *strFilename = S"Employees.bcr";
			 
	 if( File::Exists(strFilename) )
	 {
FileStream *bcrStream = new FileStream(strFilename, FileMode::Open, FileAccess::Read, FileShare::Read);
		 ArrayList *lstEmpl = dynamic_cast<ArrayList *>(bcrSoap->Deserialize(bcrStream));

		 bcrStream->Close();

		 Employee* empl;

		 lvwEmployees->Items->Clear();

		 for(int i = 0; i < lstEmpl->Count; i++)
		 {
			 empl = dynamic_cast<Employee *>(lstEmpl->Item[i]);
			 ListViewItem *lviEmployee = new ListViewItem(empl->FirstName);
			 lviEmployee->Font = new Drawing::Font("Georgia", 8, FontStyle::Bold);
		 
			if( i % 2 == 0 )
		 	{
			 	lviEmployee->BackColor = Color::Blue;
			 	lviEmployee->ForeColor = Color::White;
		 	}
		 	else
		 	{
			 	lviEmployee->BackColor = Color::LightBlue;
			 	lviEmployee->ForeColor = Color::Blue;
		 	}

			 lviEmployee->SubItems->Add(empl->LastName);
			 lviEmployee->SubItems->Add(empl->Title);
			 lviEmployee->SubItems->Add(empl->Gender);
			 lvwEmployees->Items->Add(lviEmployee);
		 }
	}
}

private: System::Void Employees_Load(System::Object *  sender, System::EventArgs *  e)
{
	 lstEmployees = new ArrayList;
	 SoapFormatter *bcrSoap = new SoapFormatter();
	 String *strFilename = S"Employees.bcr";
			 
	 if( File::Exists(strFilename) )
	 {
FileStream *bcrStream = new FileStream(strFilename, FileMode::Open, FileAccess::Read, FileShare::Read);
		 lstEmployees = dynamic_cast<ArrayList *>(bcrSoap->Deserialize(bcrStream));

		 bcrStream->Close();
	 }

	 ShowEmployees();
}

private: System::Void btnNewEmployee_Click(System::Object *  sender, System::EventArgs *  e)
{
	 NewEmployee *dlgEmpl = new NewEmployee;
				 
	 if( dlgEmpl->ShowDialog() == DialogResult::OK )
	 {
		 if( dlgEmpl->txtLastName->Text->Equals(S"") )
		 {
		 MessageBox::Show(S"You must provide at least a last name to create a new employee");
			 return;
		 }
		 else
		 {
			 String *strFilename = S"Employees.bcr";
			 Employee *empl = 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);
			 
 FileStream *bcrStream = new FileStream(strFilename, FileMode::OpenOrCreate, FileAccess::Write, FileShare::Write);
			 SoapFormatter *bcrSoap = new SoapFormatter();
			 bcrSoap->Serialize(bcrStream, lstEmployees);
			 bcrStream->Close();
						 
			 ShowEmployees();
		 }
	 }
}

private: System::Void btnClose_Click(System::Object *  sender, System::EventArgs *  e)
{
	 Close();
}

};
}

Display the first form, Form1.h [Design]. 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
In the top section of the file and under the #pragma once line, type

#include "Employees.h"

Implement the event as follows:

private: System::Void btnEmployees_Click(System::Object *  sender, System::EventArgs *  e)
{
	 Employees *frmEmpl = new Employees;

	 frmEmpl->Show();
}

Execute the application

Create a few employees as follows:

First Name	Last Name	Title	Gender
Patricia	Katts	Store Manager
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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