PayPal Standard Payment integracja w PHP

W tym tutorialu pokażę prostą integrację płatności PayPal w php. PayPal posiada swój Sandbox, w którym deweloperzy mogą testować swoje aplikacje tak jakby działały w normalnym środowisku, przy użyciu wirtualnych transakcji i pieniędzy. Gdy proces płatności PayPal działa poprawnie w środowisku Sandbox, możesz ustawić system PayPal na rzeczywiste środowisko. Najpierw musimy utworzyć konto PayPal w sandboxie. Oczywiście wcześniej musimy mieć zwykłe konto na PayPalu. Jeśli go nie mamy musimy się zarejestrować. W celu stworzenia konta na sandboxie należy wejść na stronę PayPal Developer i zalogować się do swojego konta PayPal.

CREATE TABLE `products` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
 `price` float(10,2) NOT NULL,
 `status` tinyint(1) NOT NULL DEFAULT '1',
 PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;


CREATE TABLE `payments` (
 `payment_id` int(11) NOT NULL AUTO_INCREMENT,
 `item_number` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
 `txn_id` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
 `payment_gross` float(10,2) NOT NULL,
 `currency_code` varchar(5) COLLATE utf8_unicode_ci NOT NULL,
 `payment_status` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
 PRIMARY KEY (`payment_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

<?php
//Database credentials
$host = 'domena.pl';
$username = 'username';
$pass = 'password';
$db = 'db_name';

//Connect with the database
$db = new mysqli($host, $username, $pass, $db);

//Display error if failed to connect
if ($db->connect_errno) {
    printf("Connect failed: %s\n", $db->connect_error);
    exit();
}
?>

<?php
session_start();
//Include DB configuration file
include 'config.php';

//Set useful variables for paypal form
$paypalURL = 'https://www.sandbox.paypal.com/cgi-bin/webscr'; //Test PayPal API URL
$paypalID = 'Your merchant sandbox e-mail'; //Business Email

?>
<?php
    //Fetch products from the database
    $results = $db->query("SELECT * FROM products");
    while($row = $results->fetch_assoc()){
?>
    Nazwa: <?php echo $row['name']; ?>
    Cena: <?php echo $row['price']; ?>
    <form action="<?php echo $paypalURL; ?>" method="post">
        <!-- Identify your business so that you can collect the payments. -->
        <input type="hidden" name="business" value="<?php echo $paypalID; ?>">
        
        <!-- Specify a Buy Now button. -->
        <input type="hidden" name="cmd" value="_xclick">
        
        <!-- Specify details about the item that buyers will purchase. -->
        <input type="hidden" name="item_name" value="<?php echo $row['name']; ?>">
        <input type="hidden" name="item_number" value="<?php echo $row['id']; ?>">
        <input type="hidden" name="amount" value="<?php echo $row['price']; ?>">
        <input type="hidden" name="currency_code" value="USD">
        
        <!-- Specify URLs -->
        <input type='hidden' name='cancel_return' value='url_to_file/cancel.php'>
        <input type='hidden' name='return' value='url_to_file/success.php'>
        
        <!-- Display the payment button. -->
        <input type="image" name="submit" border="0"
        src="https://www.paypalobjects.com/pl_PL/i/btn/btn_buynow_LG.gif" alt="PayPal - The safer, easier way to pay online">
        <img alt="" border="0" width="1" height="1" src="https://www.paypalobjects.com/pl_PL/i/scr/pixel.gif" >
    </form>
<?php } ?>

<?php
session_start();
include 'dbConfig.php';

if(isset($_SESSION['info'])) {
	echo $_SESSION['info'];
	unset($_SESSION['info']);
	exit;
}
//Get payment information from PayPal
$item_number = $_GET['item_number']; 
$txn_id = $_GET['tx'];
$payment_gross = $_GET['amt'];
$currency_code = $_GET['cc'];
$payment_status = $_GET['st'];

//Get product price from database
$productResult = $db->query("SELECT price FROM products WHERE id = ".$item_number);
$productRow = $productResult->fetch_assoc();
$productPrice = $productRow['price'];

if(!empty($txn_id) && $payment_gross == $productPrice) {
    //Check if payment data exists with the same TXN ID.
    $prevPaymentResult = $db->query("SELECT payment_id FROM payments WHERE txn_id = '".$txn_id."'");

    if($prevPaymentResult->num_rows > 0){
        $paymentRow = $prevPaymentResult->fetch_assoc();
        $last_insert_id = $paymentRow['payment_id'];
    }else{
        //Insert tansaction data into the database
        $insert = $db->query("INSERT INTO payments(item_number,txn_id,payment_gross,currency_code,payment_status) VALUES('".$item_number."','".$txn_id."','".$payment_gross."','".$currency_code."','".$payment_status."')");
        $last_insert_id = $db->insert_id;
    }
		$info = '<h1>Your payment has been successful. TXN ID: '.$txn_id.' Payment gross: '.$payment_gross.' Product price: '.$productPrice.'</h1>';
} else { 	
	$info = '<h1>Your payment has failed.</h1>'; 
} 
	$_SESSION['info'] = $info;
header('Location: success.php');
 
?>

Your PayPal transaction has been canceled

<input type='hidden' name='notify_url' value='url do pliku ipn.php'>

<?php 
//Include DB configuration file
include 'config.php';

/*
 * Read POST data
 * reading posted data directly from $_POST causes serialization
 * issues with array data in POST.
 * Reading raw POST data from input stream instead.
 */        
$raw_post_data = file_get_contents('php://input');
$raw_post_array = explode('&', $raw_post_data);
$myPost = array();
foreach ($raw_post_array as $keyval) {
    $keyval = explode ('=', $keyval);
    if (count($keyval) == 2)
        $myPost[$keyval[0]] = urldecode($keyval[1]);
}

// Read the post from PayPal system and add 'cmd'
$req = 'cmd=_notify-validate';
if(function_exists('get_magic_quotes_gpc')) {
    $get_magic_quotes_exists = true;
}
foreach ($myPost as $key => $value) {
    if($get_magic_quotes_exists == true && get_magic_quotes_gpc() == 1) {
        $value = urlencode(stripslashes($value));
    } else {
        $value = urlencode($value);
    }
    $req .= "&$key=$value";
}

/*
 * Post IPN data back to PayPal to validate the IPN data is genuine
 * Without this step anyone can fake IPN data
 */
$paypalURL = "https://www.sandbox.paypal.com/cgi-bin/webscr";
$ch = curl_init($paypalURL);
if ($ch == FALSE) {
    return FALSE;
}
curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
curl_setopt($ch, CURLOPT_SSLVERSION, 6);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);

// Set TCP timeout to 30 seconds
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 30);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Connection: Close', 'User-Agent: company-name'));
$res = curl_exec($ch);
/*
 * Inspect IPN validation result and act accordingly
 * Split response headers and payload, a better way for strcmp
 */ 
$tokens = explode("\r\n\r\n", trim($res));
$res = trim(end($tokens));

if (strcmp($res, "VERIFIED") == 0 || strcasecmp($res, "VERIFIED") == 0) {
    
    //Payment data
    $item_number = $_POST['item_number'];
    $txn_id = $_POST['txn_id'];
    $payment_gross = $_POST['mc_gross'];
    $currency_code = $_POST['mc_currency'];
    $payment_status = $_POST['payment_status'];
    
    //Check if payment data exists with the same TXN ID.
    $prevPayment = $db->query("SELECT payment_id FROM payments WHERE txn_id = '".$txn_id."'");
    if($prevPayment->num_rows > 0)
	{
        exit();
    } else
	{
        //Insert tansaction data into the database
        $insert = $db->query("INSERT INTO payments(item_number,txn_id,payment_gross,currency_code,payment_status) VALUES('".$item_number."','".$txn_id."','".$payment_gross."','".$currency_code."','".$payment_status."')");
    }
}
?>