PHP and MySQL Web Development - P157 pptx

Product.php Class file Contains the PHP class that stores informationon one particular book bookdisplayfunctions Functions Contains functions that help display a book and cachefunctions.

Product.php Class file Contains the PHP class that stores information

on one particular book

bookdisplayfunctions Functions Contains functions that help display a book and

cachefunctions.php Functions Contains functions to carry out the caching

required by Amazon

cartfunctions.php Functions Contains shopping cart related functions

categoryfunctions.php Functions Contains functions that help retrieve and display a

category

utilityfunctions.php Functions Contains a set of utility functions used

through-out the application

You will also need the nusoap.phpfile we mentioned previously, as it is required in these files NuSOAP is in the chapter31directory on the CD-ROM at the back of the book, but you might like to replace it with a newer version from http://

dietrich.ganx4.com/nusoap/index.php.

We will begin by looking at the core application file index.php.

Core Application

The application file index.phpis shown in Listing 31.3.

Listing 31.3 index.php—The Core Application File

<?php //we are only using one session variable 'cart' to store the cart contents session_start();

require_once('constants.php');

require_once('utilityfunctions.php');

require_once('bookdisplayfunctions.php');

require_once('cartfunctions.php');

require_once('categoryfunctions.php');

// These are the variables we are expecting from outside

// They will be validated and converted to globals

$external = array('action', 'ASIN', 'mode', 'browseNode', 'page', 'search');

// the variables may come via Get or Post // convert all our expected external variables to short global names foreach ($external as $e)

{ Table 31.1 Continued

$$e = $HTTP_POST_VARS[$e];

else if(@$HTTP_GET_VARS[$e])

$$e = $HTTP_GET_VARS[$e];

else

$$e = '';

$$e = trim($$e);

}

// default values for global variables if($mode=='')

$mode = 'books'; // No other modes have been tested if($browseNode=='')

$browseNode = 1000; //1000 is bestselling books if($page=='')

$page = 1; // First Page - there are 10 items per page

//validate/strip input if(!eregi('^[A-Z0-9]+$', $ASIN)) // ASINS must be alpha-numeric

$ASIN ='';

if(!eregi('^[a-z]+$', $mode)) // mode must be alphabetic

$mode = 'books';

$page=intval($page); // pages and browseNodes must be integers

$browseNode = intval($browseNode);

// it may cause some confusion, but we are stripping characters out from // $search it seems only fair to modify it now so it will be displayed // in the heading

$search = safeString($search);

if(!isset($HTTP_SESSION_VARS['cart'])) {

session_register('cart');

$HTTP_SESSION_VARS['cart'] = array();

}

// tasks that need to be done before the top bar is shown if($action == 'addtocart')

addToCart($HTTP_SESSION_VARS['cart'], $ASIN, $mode);

if($action == 'deletefromcart') deleteFromCart($HTTP_SESSION_VARS['cart'], $ASIN) ; if($action == 'emptycart')

$HTTP_SESSION_VARS['cart'] = array();

Listing 31.3 Continued

// show top bar require_once ('topbar.php');

// main event loop Reacts to user action on the calling page switch ($action)

{ case 'detail' : showCategories($mode);

showDetail($ASIN, $mode);

break;

case 'addtocart' : case 'deletefromcart' : case 'emptycart' : case 'showcart' : echo '<hr /><h1>Your Shopping Cart</h1>';

showCart($HTTP_SESSION_VARS['cart'], $mode);

break;

case 'image' : showCategories($mode);

echo '<h1>Large Product Image</h1>';

showImage($ASIN, $mode);

break;

case 'search' : showCategories($mode);

echo "<h1>Search Results For '$search'</h1>";

showSearch($search, $page, $mode);

break;

case 'browsenode':

default:

showCategories($mode);

$category = getCategoryName($browseNode);

if(!$category||$category=='Best Selling Books') {

echo '<h1>Current Best Sellers</h1>';

} else { echo "<h1>Current Best Sellers in $category</h1>"; }

showBrowseNode($browseNode, $page, $mode) ;

Listing 31.3 Continued

} require ('bottom.php');

? >

Let’s work our way through this file.We begin by creating a session.We will store the customer’s shopping cart as a session variable as we have done before.

We then include several files Most of these are functions that we’ll discuss later, but

we need to talk about the first included file now.This file,constants.php, defines some important constants that will be used throughout the application.The contents of con-stants.phpcan be found in Listing 31.4.

Listing 31.4 constants.php—Declaring Key Global Constants

<?php // this application can connect via XML/HTTP or SOAP // define one version of METHOD to choose

define('METHOD', 'SOAP');

//define('METHOD', 'XML/HTTP');

// make sure to create a cache directory an make it writable define('CACHE', 'cache'); // path to cached files

define('ASSOCIATEID', 'webservices-20); //put your associate id here define('DEVTAG', 'XXXXXXXXXXXXXX'); // put your developer tag here

//give an error if software is run with the dummy devtag if(DEVTAG=='XXXXXXXXXXXXXX')

die ('You need to sign up for an Amazon.com developer tag at<a href =

"http://associates.amazon.com/exec/panama/associates/join/

developer/kit.html">Amazon</a>

when you install this software You should probably sign up for an associate ID at the same time Edit the file constants.php.');

? >

This application has been developed to use either XML over HTTP or SOAP.You can set which one it should use by changing the value of the METHODconstant.

The CACHEconstant holds the path to the cache for the data we download from Amazon Change this to the path you would like used on your system.

The ASSOCIATEIDconstant holds the value of your Associate ID If you send this to Amazon with transactions, you get a commission Change this to your own Associate ID.

The DEVTAGconstant holds the value of the developer token Amazon will give you when you sign up.You need to change this to your own developer tag, or the application will not work.You can sign up for a tag at

http://associates.amazon.com/exec/panama/associates/join/developer/kit.html Listing 31.3 Continued

Let’s look back at index.php It contains some preliminaries, and then the main event loop.We begin by extracting any incoming variables that came via GETor POST.We then set up some default values for some standard global variables that determine what will be displayed later on, as follows:

// default values for global variables if($mode=='')

$mode = 'books'; // No other modes have been tested if($browseNode=='')

$browseNode = 1000; //1000 is bestselling books if($page=='')

$page = 1; // First Page - there are 10 items per page

We set the modevariable to books Amazon supports many other modes (types of prod-ucts), but for this application, we will only worry about books It should not be too hard

to modify the code in this chapter to deal with other categories.The first step in this expansion would be to reset $mode.You would need to check the Amazon documenta-tion to see what other attributes are returned for non-book products and remove book-specific language from the user interface.

The browseNodevariable is used to specify what category of books we would like displayed.This may be set if the user has clicked through one of the Selected Categories links If it is not set—for example, when the user first enters the site—we will set it to

1000 Amazon’s browse nodes are simply integers that identify a category.The value 1000

represents the category Best Selling Books, which is what we display on the initial front page.

The pagevariable is used to tell Amazon which subset of the results we would like displayed within a given category Page 1 contains results 1–10, page 2 has results 11–20, and so on Amazon sets the number of items on a page, and we do not have control over this.We could, of course, display two or more Amazon “pages” of data on one of our pages, but 10 is both a reasonable figure and the path of least resistance.

Next, we tidy up any input data we have received, whether through the search box or via GETor POSTparameters:

//validate/strip input if(!eregi('^[A-Z0-9]+$', $ASIN)) // ASINS must be alpha-numeric

$ASIN ='';

if(!eregi('^[a-z]+$', $mode)) // mode must be alphabetic

$mode = 'books';

$page=intval($page); // pages and browseNodes must be integers

$browseNode = intval($browseNode);

// it may cause some confusion, but we are stripping characters out // from $search

// it seems only fair to modify it now so it will be displayed in the // heading

$search = safeString($search) ;