6: Building a Shopping Cart Application in .NET

Drawer Code 39 in .NET 6: Building a Shopping Cart Application

data into another table that also has an identity column In that case, the @@IDENTITY function returns the identity value for the second table Fortunately, the Cart database doesn t use triggers, so the @@IDENTITY function will correctly return the identity value generated by the Orders table

The connection string used to access the Cart database is stored in the application s webconfig file, like this: <connectionStrings> <add name= ConnectionString connectionString= Data Source=localhost\SQLExpress; Initial Catalog=Cart;Integrated Security=True /> </connectionStrings> The only place in the application that references this connection string is here in the webconfig file This makes it easy to relocate the database when you put the application into production

The Shopping Cart application includes the following folders: (Root): The application s root folder contains the application s six pages (Defaultaspx, Productaspx, Cartaspx, CheckOutaspx, and Completedaspx) as well as the Master Page (Defaultmaster) App_Data: This folder is designed to store databases used by the application However, this particular application uses a database that s stored in a location that s determined by SQL Server So the database for our Cart isn t actually stored in this folder (If you use the script presented in Listing 6-1 to create the database, the database file is stored in C:\Apps) App_Code: This folder contains the C# or Visual Basic code files that define the classes used by the application For more information about these classes, see the section Designing the Classes later in this chapter Images: Here, you ll find the banner image displayed by the Master Page and the image files that show pictures of the store s products

Unlike most of the other applications presented in this book, the Shopping Cart application depends on several classes that both define the business objects used by the program as well as provide the database access In particular, the application uses the following classes: Customer: Represents a single customer ShoppingCart: Represents the user s shopping cart CartItem: Represents an item in the user s shopping cart Order: Represents an order OrderDB: Handles the details of writing an order to the database The following sections describe each of these classes in detail

The Customer class represents a single customer Its constructors and properties are spelled out in Table 6-4

Table 6-4

Customer()

Creates an instance of the Customer class with default property values Creates an instance of the Customer class with the specified property values

Customer(string lastName, string firstName, string address, string city, string state, string zipCode, string phoneNumber, string email)

The customer s street address The customer s city The customer s state The customer s Zip code The customer s phone number The customer s e-mail address

The ShoppingCart class represents a user s shopping cart Its constructors, properties, and methods are listed in Table 6-5

Table 6-5

ShoppingCart()

List<CartItem> GetItems()

Returns a List object that contains one CartItem object for each item in the shopping cart Adds a new item with the specified product ID, name, and price Updates the quantity at the specified index Deletes the item at the specified index The customer s phone number

void AddItem(string id, string name, decimal price) void UpdateQuantity (int index, int quantity) void DeleteItem(int index) string PhoneNumber

The CartItem class represents an item in the user s shopping cart Its constructors and properties are listed in Table 6-6

Table 6-6

CartItem() CartItem(string ID, string name, decimal price, int quantity)

Creates a new CartItem object with default property values Creates a new CartItem object with the specified ID, name, price, and quantity

The Product ID for the product represented by the item The product name The price per unit The quantity The total for the item (read-only)