Collection-Based Application: College Park Auto-Parts

	Collection-Based Application: College Park Auto-Parts

Introduction

The .NET Framerowk provides an impressive series of collection classes. They are organized in various namespaces. The two most common interfaces are System.Collections and System.Collections.Generics. This application is an example of using generic collection classes.

Practical Learning: Introducing the Application

Start Microsoft Visual Studio and create a new Windows Application named CollegeParkAutoParts1
In the Solution Explorer, right-click Form1.cs and click Rename
Type CollegeParkAutoParts.cs and press Enter twice to display the CollegeParkAutoParts form

The Part Description Class

A collection-based application needs a class that would be used to identify each item. For our auto-parts application, we will create a class named PartDescription. Since this is a collection-based application, the class will need to be serializable.

The class will have the following properties:

Part Number: This will be a unique number that identifies each item
Year: Since each car is manufactured in a specific year, this piece of information will serve that purpose
Make: This is the manufacturer of the vehicle
Model: This is the model of the vehicle
Part Name: This is information that identifies the part
Unit Price: This is the basic price to pay for the part

We will use two constructors. The default constructor can be used to create an empty object. Another constructor will use an argument for each property of the class. This will make it possible to create a complete object.

Practical Learning: Creating the Part Description Class

In the Solution Explorer, right-click CollegeParkAutoParts1 -> Add -> Class...
Set the name to PartDescription and press Enter

To create a class that can hold a structured item of a list, change the class as follows:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CollegeParkAutoParts1
{
    [Serializable]
    public class PartDescription
    {
        public long   PartNumber { get; set; }
        public int    Year       { get; set; }
        public string Make       { get; set; }
        public string Model      { get; set; }
        public string Category   { get; set; }
        public string PartName   { get; set; }
        public double UnitPrice  { get; set; }

        public PartDescription()
        {
            PartNumber = 0;
            Year       = 1960;
            Make       = "";
            Model      = "";
            Category   = "";
            PartName   = "Unknown";
            UnitPrice  = 0.00;
        }

        public PartDescription(long   code,  int    year, string make,
                               string model, string type,
                               string desc,  double UPrice)
        {
            PartNumber = code;
            Year       = year;
            Make       = make;
            Model      = model;
            Category   = type;
            PartName   = desc;
            UnitPrice  = UPrice;
        }

        public override string ToString()
        {
            return this.PartNumber + " " +
                   this.Year.ToString() + " " +
                   this.Make + " " +
                   this.Model + " " +
                   this.Category + " " +
                   this.PartName + " " +
                   this.UnitPrice;
        }
    }
}

Save the file

Parts Ordered

Our auto parts business sells objects. Whenever an object is sold, we must enter its information in an invoice. To keep track of this, we will use a class that resembles that of the part description.

Practical Learning: Creating the Part Ordered Class

In the Solution Explorer, right-click CollegeParkAutoParts1 -> Add -> Class...
Set the name to PartsOrdered and press Enter

To create another class independent for a list, change the document as follows:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CollegeParkAutoParts1
{
    [Serializable]
    public class PartsOrdered
    {
        public long PartNumber  { get; set; }
        public string PartName  { get; set; }
        public double UnitPrice { get; set; }
        public int Quantity     { get; set; }
        public double SubTotal  { get; set; }
    }
}

Save the file

Parts Organization

Auto parts are organized from their characteristics such as the vehicle make, the model, and the category. We will need dialog boxes that can assist a user with creating those pieces of information.

Practical Learning: Creating the Parts Accessories

To create a dialog box, on the main menu, click PROJECT -> Add Windows Form...
Set the name to Make and click Add

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 Property

Value

FormBorderStyle

FixedDialog

Text

Make Editor

StartPosition

CenterScreen

AcceptButton

btnOK

CancelButton

btnCancel

MaximizeBox

False

MinimizeBox

False

ShowInTaskbar

False

To create a dialog box, on the main menu, click PROJECT -> Add Windows Form...
Set the name to Model and click Add

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 Property

Value

FormBorderStyle

FixedDialog

Text

Model Editor

StartPosition

CenterScreen

AcceptButton

btnOK

CancelButton

btnCancel

MaximizeBox

False

MinimizeBox

False

ShowInTaskbar

False

To create a dialog box, in the Solution Explorer, right-click CollegeParkAutoParts1 -> Add -> Windows Form...
Set the name to Category and click Add

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 Property

Value

FormBorderStyle

FixedDialog

Text

Category Editor

StartPosition

CenterScreen

AcceptButton

btnOK

CancelButton

btnCancel

MaximizeBox

False

MinimizeBox

False

ShowInTaskbar

False

Save all

Part Identification

Probably the most important piece of information about an item sold in a store is its name. When it comes to a business, the second most important piece of information about an item is its cost. When it comes to a database, the most important piece of information about an item is a (unique) number used to identify it. We will create a dialog box that a user can use to create an item sold in the store.

Practical Learning: Creating a Dialog Box for Parts

On the main menu, click PROJECT -> Add Windows Form...
Set the Name to NewStoreItem and click Add

Design the form as follows:

Control	Text	Name	Other Properties
Label	&Year:
TextBox		txtItemNumber
Label	&Make:
ComboBox		cbxMakes
Button	New C&ategory...	btnNewMake
Label	M&odel:
ComboBox		cbxModels
Button	New Mo &del...	btnNewModel
Label	&Category:
ComboBox		cbxCategories
Button	New Ca&tegory	btnNewCategory
Label	&Unit Price:
TextBox	0.00	txtUnitPrice	TextAlign: Right
Label	Part #:
TextBox		txtPartNumber
Label	&Part Name:
TextBox		txtPartName
Button	Submit	btnSubmit
Button	Close	btnClose	DialogResult: Cancel

Form Property

Value

FormBorderStyle

FixedDialog

Text

College Park Auto -Parts: Part Editor

StartPosition

CenterScreen

MaximizeBox

False

MinimizeBox

False

ShowInTaskbar

False

Double-click the New Make button and implement it as follows:

 private void btnNewMake_Click(object sender, EventArgs e)
{
    Make editor = new Make();

    if (editor.ShowDialog() == DialogResult.OK)
    {
        if (editor.txtMake.Text.Length > 0)
        {
            string strMake = editor.txtMake.Text;

            // Make sure the category is not yet in the list
            if (cbxMakes.Items.Contains(strMake))
                MessageBox.Show(strMake + " is already in the list.",
                                "College Park Auto-Parts",
                             MessageBoxButtons.OK, MessageBoxIcon.Information);
            else
            {
                // Since this is a new category, add it to the combo box
                cbxMakes.Items.Add(strMake);
            }

            cbxMakes.Text = strMake;
        }
    }
}

Return to the New Store Item dialog box and double-click the New Model button

Implement the event as follows:

private void btnNewModel_Click(object sender, EventArgs e)
{
    Model editor = new Model();

    if (editor.ShowDialog() == DialogResult.OK)
    {
        if (editor.txtModel.Text.Length > 0)
        {
            string strModel = editor.txtModel.Text;

            // Make sure the category is not yet in the list
            if (cbxModels.Items.Contains(strModel))
                MessageBox.Show(strModel + " is already in the list.",
                                "College Park Auto-Parts",
                              MessageBoxButtons.OK, MessageBoxIcon.Information);
            else
            {
                // Since this is a new category, add it to the combo box
                cbxModels.Items.Add(strModel);
            }

            cbxModels.Text = strModel;
        }
    }
}

Return to the New Store Item dialog box and double-click the New Category button

Implement the event as follows:

private void btnNewCategory_Click(object sender, EventArgs e)
{
    Category editor = new Category();

    if (editor.ShowDialog() == DialogResult.OK)
    {
        if (editor.txtCategory.Text.Length > 0)
        {
            string strCategory = editor.txtCategory.Text;

            // Make sure the category is not yet in the list
            if (cbxCategories.Items.Contains(strCategory))
                MessageBox.Show(strCategory + " is already in the list.",
                                "College Park Auto-Parts",
                             MessageBoxButtons.OK, MessageBoxIcon.Information);
            else
            {
                // Since this is a new category, add it to the combo box
                cbxCategories.Items.Add(strCategory);
            }
            
            cbxCategories.Text = strCategory;
        }
    }
}

Save all

The Main Form

When this application starts, it will display the main form from where a user can locate and select a part. On the left side of the form, we will create a tree view that displays nodes from which a user can select a car year, a vehicle make, and a model. Then, the user can select a category. This would cause a list view on the right side of the form to display the parts that fit the criteria from the tree view.

Practical Learning: Enumerating a List

Display the CollegeParkAutoParts form
From the Components section of the Toolbox, click ImageList and click the form
In the Properties window, click (Name) and type AutoPartsImages
Click the ellipsis button of the Images field
In the Image Collection Editor, click Add
Locate the folder that contains the resources for these lessons and display it in the Look In combo box
Select the following icons: Sign1, Sign2, Cliper1, Cliper2, Rulers1, Rulers2, Graph1, Graph2, Tool1, and Tool2
Click Open
Click OK

Design the form as follows:

Control	Text	Name	Other Properties
Label	College Park Auto-Parts		Font: Times New Roman, 20.25pt, style=Bold ForeColor: Blue
Panel			Height: 2
GroupBox	Part Identification
TreeView		tvwAutoParts	ImageList: AutoPartsImages
GroupBox	Available Parts
ListView		lvwAutoParts	FullRowSelect: True GridLines: True View: Details
Columns	(Name)	Text	TextAlign	Width
	colPartNumber	Part #
	colPartName	Part Name		300
	colUnitPrice	Unit Price	Right	80
GroupBox	Customer Order - Selected Parts
Label	Part #
Label	Part Name
Label	Unit Price
Label	Qty
Label	Sub Total
TextBox		txtPartNumber
TextBox		txtPartName
TextBox	0.00	txtUnitPrice	TextAlign: Right
TextBox	0	txtQuantity	TextAlign: Right
TextBox	0.00	txtSubTotal	TextAlign: Right
Button	Add/Select	btnAdd
ListView		lvwSelectedParts	FullRowSelect: True GridLines: True View: Details
Columns	(Name)	Text	TextAlign	Width
	colPartNumberSelected	Part #		45
	colPartNameSelected	Part Name		274
	colUnitPriceSelected	Unit Price	Right	58
	colQuantitySelected	Qty	Right	28
	colSubTotalSelected	Sub-Total	Right	58
GroupBox	Order Summary
Button	New Au&to Part...	btnNewAutoPart
Label	Receipt #:
TextBox		txtSave
Button	Save	btnSave
Label	Tax Rate:
TextBox	7.75	txtTaxRate	TextAlign: Right
Label	%
Label	Parts Total:
TextBox	0.00	txtPartsTotal	TextAlign: Right
Button	&New Customer Order	btnNewCustomerOrder
Label	Receipt #:
TextBox		txtOpen
Button	Save	btnOpen
Label	Tax Amount:
TextBox	0.00	txtTaxAmount	TextAlign: Right
Label	Order Total:
TextBox	0.00	txtOrderTotal	TextAlign: Right
Button	Close	btnClose

Click the Available Parts list view
In the Properties window, click the Events button and, in the Events section, double-click DoubleClick

Implement the event as follows:

private void lvwAutoParts_DoubleClick(object sender, EventArgs e)
{
    ListViewItem lviAutoPart = lvwAutoParts.SelectedItems[0];

    if ((lvwAutoParts.SelectedItems.Count == 0) ||
        (lvwAutoParts.SelectedItems.Count > 1))
        return;

    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();
}

Return to the College Park Auto-Parts form
Click the Unit Price text box
On the Properties window, click the Events button and double-click Leave

Implement the event as follows:

private void txtUnitPrice_Leave(object sender, EventArgs e)
{
    double unitPrice = 0.00D;
    double quantity = 0;
    double subTotal = 0.00D;

    try
    {
        unitPrice = double.Parse(txtUnitPrice.Text);
    }
    catch (FormatException)
    {
        MessageBox.Show("Invalid Unit Price!",
                        "College Park Auto-Parts",
                        MessageBoxButtons.OK, MessageBoxIcon.Information);
    }

    try
    {
    	quantity = int.Parse(txtQuantity.Text);
    }
    catch (FormatException)
    {
        MessageBox.Show("Invalid Quandtity!",
                        "College Park Auto-Parts",
                        MessageBoxButtons.OK, MessageBoxIcon.Information);
    }

    subTotal = unitPrice * quantity;
    txtSubTotal.Text = subTotal.ToString("F");
}

internal void CalculateOrder()
{
    // Calculate the current total order and update the order
    double PartsTotal = 0.00D;
    double TaxRate = 0.00D;
    double TaxAmount = 0.00D;
    double OrderTotal = 0.00D;
            
    foreach (ListViewItem lvi in lvwSelectedParts.Items)
    {
        ListViewItem.ListViewSubItem SubItem = lvi.SubItems[4];
        PartsTotal += double.Parse(SubItem.Text);
    }

    try
    {
        TaxRate = double.Parse(txtTaxRate.Text) / 100;
    }
    catch (FormatException)
    {
        MessageBox.Show("Invalid Tax Rate",
                        "College Park Auto-Parts",
                        MessageBoxButtons.OK, MessageBoxIcon.Information);
    }

    TaxAmount = PartsTotal * TaxRate;
    OrderTotal = PartsTotal + TaxAmount;

    txtPartsTotal.Text = PartsTotal.ToString("F");
    txtTaxAmount.Text = TaxAmount.ToString("F");
    txtOrderTotal.Text = OrderTotal.ToString("F");
}

Return to the College Park Auto-Parts form and click the Qty text box
In the Events section of the Properties, click Leave, then click the arrow of its combo box and select txtUnitPrice_Leave
Return to the College Park Auto-Parts form and click the Selected Parts list view (the list view in the bottom-right section of the form)
In the Events section of the Properties window, double-click DoubleClick

Implement the event as follows:

private void lvwSelectedParts_DoubleClick(object sender, EventArgs e)
{
    ListViewItem lviSelectedPart = lvwSelectedParts.SelectedItems[0];

    if( (lvwSelectedParts.SelectedItems.Count == 0) ||
        (lvwSelectedParts.SelectedItems.Count > 1) )
        return;

    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();
}

Save all

Creating a Store Item

The primary operation to be performed on a database is to create an item. For our auto-parts business, this consists of creating an object based on the PartDecription class. When the object has been created, it is added to the collection class. For our application, we will use the List<> class that is defined in the System.Collections.Generics namespace. That class is equipped with all the methods and properties necessary for our collection-based application.

Practical Learning: Adding Items to an ArrayList List

Display the New Store Item form and double-click the Submit button

Implement the event as follows:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

namespace CollegeParkAutoParts1
{
    public partial class NewStoreItem : Form
    {
        List<PartDescription> lstAutoParts;

        . . . No Change

        private void btnSubmit_Click(object sender, EventArgs e)
        {
            FileStream stmAutoParts = null;
            BinaryFormatter bfmAutoParts = new BinaryFormatter();

            // If this directory doesn't exist, create it
            Directory.CreateDirectory(@"C:\College Park Auto Parts");
            // This is the file that holds the list of items
            string FileName = @"C:\College Park Auto Parts\Parts.prs";

            // Create a random number that will be used to identify the item
            Random rnd = new Random();
            txtPartNumber.Text = rnd.Next(100000, 999999).ToString();

            // Make sure the user had selected a make
            if (cbxYears.Text.Length == 0)
            {
                MessageBox.Show("You must specify the year.",
                                "College Park Auto-Parts",
                                MessageBoxButtons.OK, MessageBoxIcon.Information);
                cbxYears.Focus();
                return;
            }

            // Make sure the user had selected a make
            if (cbxMakes.Text.Length == 0)
            {
                MessageBox.Show("You must specify the car name.",
                                "College Park Auto-Parts",
                                MessageBoxButtons.OK, MessageBoxIcon.Information);
                cbxMakes.Focus();
                return;
            }

            // Make sure the user had selected a model
            if (cbxModels.Text.Length == 0)
            {
                MessageBox.Show("You must specify the model of the car.",
                                "College Park Auto-Parts",
                                MessageBoxButtons.OK, MessageBoxIcon.Information);
                cbxModels.Focus();
                return;
            }

            // Make sure the user had selected the part category
            if (cbxCategories.Text.Length == 0)
            {
                MessageBox.Show("You must specify the part's category.",
                                "College Park Auto-Parts",
                                MessageBoxButtons.OK, MessageBoxIcon.Information);
                cbxCategories.Focus();
                return;
            }

            // Make sure the user had entered a name/description
            if (txtPartName.Text.Length == 0)
            {
                MessageBox.Show("You must enter the name (or a " +
                                "short description) for the part.",
                                "College Park Auto-Parts",
                                MessageBoxButtons.OK, MessageBoxIcon.Information);
                txtPartName.Focus();
                return;
            }

            // Make sure the user had typed a price for the item
            if (txtUnitPrice.Text.Length == 0)
            {
                MessageBox.Show("You must enter the price of the item.",
                                "College Park Auto-Parts",
                                MessageBoxButtons.OK, MessageBoxIcon.Information);
                txtUnitPrice.Focus();
                return;
            }

            // Before saving the new part, find out if there was
            // already a file that holds the list of parts
            // If that file exists, open it and store its parts 
            // in our lstParts variable
            if (File.Exists(FileName))
            {
                using( stmAutoParts = new FileStream(FileName,
                                              FileMode.Open,
                                              FileAccess.Read,
                                              FileShare.Read) )
                {
                    // Retrieve the list of items from file
     lstAutoParts = (List<PartDescription>)bfmAutoParts.Deserialize(stmAutoParts);
                }
            }

            // Create the part
            PartDescription part = new PartDescription();
            part.PartNumber = long.Parse(txtPartNumber.Text);
            part.Year = int.Parse(cbxYears.Text);
            part.Make = cbxMakes.Text;
            part.Model = cbxModels.Text;
            part.Category = cbxCategories.Text;
            part.PartName = txtPartName.Text;
            part.UnitPrice = double.Parse(txtUnitPrice.Text);

            // Call the Add method of our collection class to add the part
            lstAutoParts.Add(part);

            // Save the list
            using( stmAutoParts = new FileStream(FileName,
                   	                         FileMode.Create,
                        	                 FileAccess.Write,
                                	         FileShare.Write) )
            {
                bfmAutoParts.Serialize(stmAutoParts, lstAutoParts);

                // After saving the item, reset the form
                cbxYears.Text = "";
                cbxMakes.Text = "";
                cbxModels.Text = "";
                cbxCategories.Text = "";
                txtPartName.Text = "";
                txtUnitPrice.Text = "0.00";
                txtPartNumber.Text = rnd.Next(100000, 999999).ToString();
            }
        }
    }
}

In the Solution Explorer, double-click CollegeParkAutoParts.cs and double-click the Save button

Implement its event as follows:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

namespace CollegeParkAutoParts1
{
    public partial class CollegeParkAutoParts : Form
    {
        int iFileName; // This variable will be used later
        List<PartDescription> lstAutoParts;

        public CollegeParkAutoParts()
        {
            InitializeComponent();
        }

        . . . No Change
            
        private void btnSave_Click(object sender, EventArgs e)
        {
            BinaryFormatter bfmCustomerOrder = new BinaryFormatter();

            // We will store our files in the following folder    
            string strDirectory = @"C:\College Park Auto Parts\Receipts";
            DirectoryInfo dirInfo = new DirectoryInfo(strDirectory);

            string strFilename = strDirectory + "\\" + txtSave.Text + ".cap";

            List<PartsOrdered> lstOrderedParts = null;

            if (lvwSelectedParts.Items.Count == 0)
                return;
            else
            {
                lstOrderedParts = new List<PartsOrdered>();

                for (int i = 0; i < lvwSelectedParts.Items.Count; i++)
                {
                    PartsOrdered part = new PartsOrdered();

                    part.PartNumber = long.Parse(lvwSelectedParts.Items[i].Text);
                    part.PartName = lvwSelectedParts.Items[i].SubItems[1].Text;
                    part.UnitPrice = double.Parse(lvwSelectedParts.Items[i].SubItems[2].Text);
                    part.Quantity = int.Parse(lvwSelectedParts.Items[i].SubItems[3].Text);
                    part.SubTotal = double.Parse(lvwSelectedParts.Items[i].SubItems[4].Text);
                    lstOrderedParts.Add(part);
                }

                using (FileStream stmCustomerOrder = new FileStream(strFilename, FileMode.Create))
                {
                    bfmCustomerOrder.Serialize(stmCustomerOrder, lstOrderedParts);
                    stmCustomerOrder.Close();
                }
            }
        }
    }
}

Save all
Display the New Store Item form and double-click the Makes combo box

Implement its SelectedIndexChanged event as follows:

private void cbxMakes_SelectedIndexChanged(object sender, EventArgs e)
{
    cbxModels.Text = "";
    cbxModels.Items.Clear();

    foreach (PartDescription part in lstAutoParts)
        if (part.Make == cbxMakes.Text)
            if (!cbxModels.Items.Contains(part.Model))
                cbxModels.Items.Add(part.Model);
}

Display the College Park Auto-Parts form and double-click the Add/Select button

Implement the event as follows:

private void btnAdd_Click(object sender, EventArgs e)
{
    if (txtPartNumber.Text.Length == 0)
    {
        MessageBox.Show("There is no part to be added to the order.",
                        "College Park Auto-Parts",
                        MessageBoxButtons.OK, MessageBoxIcon.Information);
        return;
    }

    foreach (PartDescription part in lstAutoParts)
    {
        if (part.PartNumber == long.Parse(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();
}

Return to the College Partk Auto-Parts form and double-click the Open button

Implement its event as follows:

private void btnOpen_Click(object sender, EventArgs e)
{
    List<PartsOrdered> lstReceipts = null;
    BinaryFormatter bfmReceipts = new BinaryFormatter();
    FileStream stmReceipts = null;

    string strDirectory = @"C:\College Park Auto Parts\Receipts";
    string strFilename = "";

    DirectoryInfo dirReceipts = new DirectoryInfo(strDirectory);
    FileInfo[] fleReceipts = dirReceipts.GetFiles();

    if (txtOpen.Text.Length == 0)
    {
        MessageBox.Show("You must enter a receipt number\n" +
                        "There is no receipt number to " +
                        "open a customer's order.",
                        "College Park Auto-Parts",
                        MessageBoxButtons.OK, MessageBoxIcon.Information);
        txtOpen.Focus();
        return;
    }

    if (fleReceipts.Length == 0)
    {
        MessageBox.Show("There is no customer order to open.",
                        "College Park Auto-Parts",
                        MessageBoxButtons.OK, MessageBoxIcon.Information);
        txtOpen.Focus();
        return;
    }
    else
    {
        lvwAutoParts.Items.Clear();
        lvwSelectedParts.Items.Clear();

        strFilename = strDirectory + "\\" + txtOpen.Text + ".cap";

        if (File.Exists(strFilename))
        {
            using( stmReceipts = new FileStream(strFilename, FileMode.Open) )
            {
           lstReceipts = (List<PartsOrdered>)bfmReceipts.Deserialize(stmReceipts);

                foreach (PartsOrdered part in lstReceipts)
                {
                    ListViewItem lviReceiptPart =
			new ListViewItem(part.PartNumber.ToString());

                    lviReceiptPart.SubItems.Add(part.PartName);
                    lviReceiptPart.SubItems.Add(part.UnitPrice.ToString());
                    lviReceiptPart.SubItems.Add(part.Quantity.ToString());
                    lviReceiptPart.SubItems.Add(part.SubTotal.ToString());
                    lvwSelectedParts.Items.Add(lviReceiptPart);
                }
            }

            CalculateOrder();
            txtSave.Text = txtOpen.Text;
        }
        else
            MessageBox.Show("There is no customer order with that receipt number.",
	                    "College Park Auto-Parts",
        	            MessageBoxButtons.OK, MessageBoxIcon.Information);
    }
}

Display the New Store Item form and double-click an unoccupied area of its body

Implement the Load event as follows:

private void NewStoreItem_Load(object sender, EventArgs e)
{
    // Since all values seem ready, prepare to process the item
    lstAutoParts = new List<PartDescription>();
    BinaryFormatter bfmAutoParts = new BinaryFormatter();

    for (int i = DateTime.Today.Year + 1; i >= 1960; i--)
        cbxYears.Items.Add(i.ToString());

    // Create a random number that will be used to identify the item
    Random rnd = new Random();
    txtPartNumber.Text = rnd.Next(100000, 999999).ToString();

    // This is the file that holds the list of parts
    string FileName = @"C:\College Park Auto Parts\Parts.prs";

    if (File.Exists(FileName))
    {
        using (FileStream stmAutoParts = new FileStream(FileName,
	                                                FileMode.Open,
        	                	                FileAccess.Read,
                		                	FileShare.Read))
        {
            // Retrieve the list of items from file
            lstAutoParts = (List<PartDescription>)bfmAutoParts.Deserialize(stmAutoParts);

            // Display the car manufacturers in the Make combo box
            foreach (PartDescription part in      lstAutoParts )
            {
                if (!cbxMakes.Items.Contains(part.Make))
                    cbxMakes.Items.Add(part.Make);
            }

            // Display the pats categories in the Category combo box
            foreach (PartDescription part in      lstAutoParts )
            {
                if (!cbxCategories.Items.Contains(part.Category))
                    cbxCategories.Items.Add(part.Category);
            }
        }
    }
}

Display the College Park Auto-Parts form and click the Part # text box

In the Events section of the Properties window, double-click Leave and implement the event as follows:

private void txtPartNumber_Leave(object sender, EventArgs e)
{
    // We will allow the user to enter a part number
    // In the beginning, we assume that the user 
    // had entered an invalid number
    bool found = false;
    // This will represent the part found, if any
    PartDescription partFound = null;

    // After the user had entered a part number,
    // check the whole list of parts
    foreach (PartDescription part in lstAutoParts)
    {
        // If you find a part that holds the number the user had entered
        if( part.PartNumber == long.Parse(txtPartNumber.Text) )
        {
            // Mark that part
            partFound = part;
            // And update the flag that specifies that the part has been found
            found = true;
        }
        // If the part number was not found, check the next
    } // If no part has that number, the found flag keeps marked as false

    // If a part with that number was found...
    if (found == true)
    {
        // Show the corresponding part name and unit price
        txtPartName.Text  = partFound.PartName;
        txtUnitPrice.Text = partFound.UnitPrice.ToString("F");
        txtQuantity.Text  = "1";
        txtSubTotal.Text  = partFound.UnitPrice.ToString("F");
        // Give focus to the quantity in case the user was to increase it
        txtQuantity.Focus();
    }
    else
    {
        // Since no part with that number was found,
        // reset the text boxes
        txtPartName.Text = "";
        txtUnitPrice.Text = "0.00";
        txtQuantity.Text = "0";
        txtSubTotal.Text = "0.00";

        // Let the user know that the part number that 
        // was entered is not in the list
        MessageBox.Show("There is no part with that number.",
	                "College Park Auto-Parts",
        	        MessageBoxButtons.OK, MessageBoxIcon.Information);
    }
}

Return to the College Park Auto-Parts form and double-click the New Auto Part button

Implement the event as follows:

void ShowAutoParts()
{
    tvwAutoParts.Nodes.Clear();
    TreeNode nodRoot = tvwAutoParts.Nodes.Add("College Park Auto-Parts",
                                "College Park Auto-Parts", 0, 1);
    // Show the years nodes
    for (int years = DateTime.Today.Year + 1; years >= 1960; years--)
        nodRoot.Nodes.Add(years.ToString(), years.ToString(), 2, 3);

    tvwAutoParts.SelectedNode = nodRoot;
    // Expand the root node
    tvwAutoParts.ExpandAll();

    lstAutoParts = new List<PartDescription>();
    BinaryFormatter bfmAutoParts = new BinaryFormatter();

    // This is the file that holds the list of auto parts
    string FileName = @"C:\College Park Auto Parts\Parts.prs";

    if (File.Exists(FileName))
    {
        using (FileStream stmAutoParts = new FileStream(FileName,
                                                FileMode.Open,
                                                FileAccess.Read,
                                                FileShare.Read))
        {
            // Retrieve the list of parts from file
            lstAutoParts = (List<PartDescription>)bfmAutoParts.Deserialize(stmAutoParts);

            // Show the makes nodes
            foreach (TreeNode nodYear in nodRoot.Nodes)
            {
                List<string> lstMakes = new List<string>();

                foreach (PartDescription part in lstAutoParts)
                {
                    if (nodYear.Text == part.Year.ToString())
                    {
                        if (!lstMakes.Contains(part.Make))
                            lstMakes.Add(part.Make);
                    }
                }

                foreach (string strMake in lstMakes)
                    nodYear.Nodes.Add(strMake, strMake, 4, 5);
            }

            // Showing the models nodes
            foreach (TreeNode nodYear in nodRoot.Nodes)
            {
                foreach (TreeNode nodMake in nodYear.Nodes)
                {
                    List<string> lstModels = new List<string>();

                    foreach (PartDescription part in lstAutoParts)
                    {

                        if ((nodYear.Text == part.Year.ToString()) &&
                            (nodMake.Text == part.Make))
                        {
                            if (!lstModels.Contains(part.Model))
                                lstModels.Add(part.Model);

                        }
                    }

                    foreach (string strModel in lstModels)
                        nodMake.Nodes.Add(strModel, strModel, 6, 7);
                }
            }

            // Showing the categories nodes
            foreach (TreeNode nodYear in nodRoot.Nodes)
            {
                foreach (TreeNode nodMake in nodYear.Nodes)
                {
                    foreach (TreeNode nodModel in nodMake.Nodes)
                    {
                        List<string> lstCategories = new List<string>();

                        foreach (PartDescription part in lstAutoParts)
                        {

                            if ((nodYear.Text == part.Year.ToString()) &&
                                (nodMake.Text == part.Make) &&
                                (nodModel.Text == part.Model))
                            {
                                if (!lstCategories.Contains(part.Category))
                                    lstCategories.Add(part.Category);
                            }
                        }

                        foreach (string strCategory in lstCategories)
                            nodModel.Nodes.Add(strCategory,
                        strCategory, 8, 9);
                    }
                }
            }
        }
    }
}

private void btnNewAutoPart_Click(object sender, EventArgs e)
{
    NewStoreItem editor = new NewStoreItem();

    if (editor.ShowDialog() == DialogResult.Cancel)
        ShowAutoParts();
}

Return to the College Park Auto-Parts form and double- click the New Customer Order button

Implement the event as follows:

private void btnNewCustomerOrder_Click(object sender, EventArgs e)
{
    // We will store our files in the following folder    
    string strDirectory = @"C:\College Park Auto Parts\Receipts";
    DirectoryInfo dirInfo = Directory.CreateDirectory(strDirectory);

    // Get the list of files, if any, from our directory
    FileInfo[] fleList = dirInfo.GetFiles();

    // If there is no file in the directory,
    // then we will use 1000 as the first file name
    if (fleList.Length == 0)
    {
        iFileName = 1000;
    }
    else // If there was at least one file in the directory
    {
        // Get a reference to the last file
        FileInfo fleLast = fleList[fleList.Length - 1];
        // Get the name of the last file without its extension
        string fwe = Path.GetFileNameWithoutExtension(fleLast.FullName);
        // Increment the name of the file by 1
        iFileName = int.Parse(fwe) + 1;
    }

    txtSave.Text = iFileName.ToString();

    lvwAutoParts.Items.Clear();
    lvwSelectedParts.Items.Clear();
}

Return to the College Park Auto-Parts form and double-click an unoccupied area of its body

Define a new method and implement the Load event as follows:

private void Central_Load(object sender, EventArgs e)
{
    ShowAutoParts();
    btnNewCustomerOrder_Click(sender, e);
}

Return to the College Park Auto-Parts form and click the tree view
In the Events section of the Properties window, double-click NodeMouseClick

Implement the event as follows:

private void tvwAutoParts_NodeMouseClick(object sender,
			TreeNodeMouseClickEventArgs e)
{
    TreeNode nodClicked = e.Node;

    if (nodClicked.Level == 4)
        lvwAutoParts.Items.Clear();

    try
    {
        foreach (PartDescription part in lstAutoParts)
        {
            if ((part.Category == nodClicked.Text) &&
                (part.Model == nodClicked.Parent.Text) &&
                (part.Make == nodClicked.Parent.Parent.Text) &&
                (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.ToString("F"));
                lvwAutoParts.Items.Add(lviAutoPart);
            }
        }
    }
    catch (NullReferenceException)
    {
    }
}

Return to the College Park Auto-Parts form and double-click the Close button

Implement the event as follows:

private void btnClose_Click(object sender, EventArgs e)
{
    Close();
}

Execute the application
Click the New Auto Part button and use the Part Editor to create a few parts (let the computer generate the part numbers)
Close the Part Editor
Create a few customer part orders and save them:
Close the forms and return to your programming environment
Execute the application again and open a previously saved order
Close the forms and return to your programming environment

Application