PayPal Payment Gateway Integration in CodeIgniter

CREATE TABLE `products` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
 `image` varchar(200) COLLATE utf8_unicode_ci NOT NULL,
 `price` float(10,2) NOT NULL,
 `currency` varchar(10) COLLATE utf8_unicode_ci NOT NULL DEFAULT 'USD',
 `status` enum('1','0') COLLATE utf8_unicode_ci NOT NULL DEFAULT '1',
 PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

CREATE TABLE `payments` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `product_id` int(11) NOT NULL,
 `user_id` int(11) DEFAULT NULL,
 `txn_id` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
 `payment_gross` float(10,2) NOT NULL,
 `currency_code` varchar(5) COLLATE utf8_unicode_ci NOT NULL,
 `payer_name` varchar(50) COLLATE utf8_unicode_ci NOT NULL,
 `payer_email` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
 `status` varchar(20) COLLATE utf8_unicode_ci NOT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

<?php  defined('BASEPATH') OR exit('No direct script access allowed'); 
 
/* 
| ------------------------------------------------------------------- 
|  PayPal API Configuration 
| ------------------------------------------------------------------- 
| 
| You will get the API keys from Developers panel of the PayPal account 
| Login to PayPal account (https://developer.paypal.com/) 
| and navigate to the SANDBOX » Accounts page 
| Remember to switch to your live business email in production! 
| 
|  sandbox                    boolean  PayPal environment, TRUE for Sandbox and FALSE for live 
|  business                    string   PayPal business email 
|  paypal_lib_currency_code string   Currency code. 
*/ 
 
$config['sandbox'] = TRUE; // FALSE for live environment 
 
$config['business'] = 'test@business.com'; 
 
$config['paypal_lib_currency_code'] = 'USD'; 
 
// Where is the button located at? (optional) 
$config['paypal_lib_button_path'] = 'assets/images/'; 
 
// If (and where) to log ipn response in a file 
$config['paypal_lib_ipn_log'] = FALSE; 
$config['paypal_lib_ipn_log_file'] = BASEPATH . 'logs/paypal_ipn.log';

<?php defined('BASEPATH') OR exit('No direct script access allowed'); 
/** 
 * PayPal Library for CodeIgniter 3.x 
 * 
 * Library for PayPal payment gateway. It helps to integrate PayPal payment gateway 
 * in the CodeIgniter application. 
 * 
 * It requires PayPal configuration file and it should be placed in the config directory. 
 * 
 * @package     CodeIgniter 
 * @category    Libraries 
 * @author      TorqueProgrammer 
 * @license     http://www.torqueprogramming.co.in/license/ 
 * @link        http://www.torqueprogramming.co.in 
 * @version     2.0 
 */ 
 
class Paypal_lib 
{ 
 
    var $last_error;            // holds the last error encountered 
    var $ipn_log;                // bool: log IPN results to text file? 
 
    var $ipn_log_file;            // filename of the IPN log 
    var $ipn_response;            // holds the IPN response from paypal     
    var $ipn_data = array();    // array contains the POST values for IPN 
    var $fields = array();        // array holds the fields to submit to paypal 
 
    var $submit_btn = '';        // Image/Form button 
    var $button_path = '';        // The path of the buttons 
     
    var $CI; 
     
    function __construct(){ 
        $this->CI =& get_instance(); 
        $this->CI->load->helper('url'); 
        $this->CI->load->helper('form'); 
        $this->CI->load->config('paypal'); 
         
        $sanbox = $this->CI->config->item('sandbox'); 
        $this->paypal_url = ($sanbox == TRUE)?'https://www.sandbox.paypal.com/cgi-bin/webscr':'https://www.paypal.com/cgi-bin/webscr'; 
                 
        $this->last_error = ''; 
        $this->ipn_response = ''; 
 
        $this->ipn_log_file = $this->CI->config->item('paypal_lib_ipn_log_file'); 
        $this->ipn_log = $this->CI->config->item('paypal_lib_ipn_log');  
         
        $this->button_path = $this->CI->config->item('paypal_lib_button_path'); 
         
        // populate $fields array with a few default values. 
        // values can be overwritten by the calling script. 
        $businessEmail = $this->CI->config->item('business'); 
        $this->add_field('business',$businessEmail); 
        $this->add_field('rm','2');    // Return method = POST 
        $this->add_field('cmd','_xclick'); 
 
        $this->add_field('currency_code', $this->CI->config->item('paypal_lib_currency_code')); 
        $this->add_field('quantity', '1'); 
        $this->button('Pay Now!'); 
    } 
 
    function button($value){ 
        // changes the default caption of the submit button 
        $this->submit_btn = form_submit('pp_submit', $value); 
    } 
 
    function image($file){ 
        $this->submit_btn = '<input type="image" name="add" src="'.base_url(rtrim($this->button_path, '/').'/'. $file).'" border="0" />'; 
    } 
 
    function add_field($field, $value){ 
        // adds a key=>value pair to the fields array, which is what will be  
        // sent to paypal as POST variables.  If the value is already in the  
        // array, it will be overwritten. 
        $this->fields[$field] = $value; 
    } 
 
    function paypal_auto_form(){ 
        // this function actually generates an entire HTML page consisting of 
        // a form with hidden elements which is submitted to paypal via the  
        // BODY element's onLoad attribute. 
        $this->button('Click here if you\'re not automatically redirected...'); 
 
        echo '<html>' . "\n"; 
        echo '<head><title>Processing Payment...</title></head>' . "\n"; 
        echo '<body style="text-align:center;" onLoad="document.forms[\'paypal_auto_form\'].submit();">' . "\n"; 
        echo '<p style="text-align:center;">Please wait, your order is being processed and you will be redirected to the PayPal website.</p>' . "\n"; 
        echo $this->paypal_form('paypal_auto_form'); 
        echo '</body></html>'; 
    } 
 
    function paypal_form($form_name='paypal_form'){ 
        $str = ''; 
        $str .= '<form method="post" action="'.$this->paypal_url.'" name="'.$form_name.'"/>' . "\n"; 
        foreach ($this->fields as $name => $value) 
            $str .= form_hidden($name, $value) . "\n"; 
        $str .= '<p>'. $this->submit_btn . '</p>'; 
        $str .= form_close() . "\n"; 
 
        return $str; 
    } 
     
    function validate_ipn($paypalReturn){ 
        $ipn_response = $this->curlPost($this->paypal_url, $paypalReturn); 
         
        if(preg_match("/VERIFIED/i", $ipn_response)){ 
            // Valid IPN transaction. 
            return true; 
        }else{ 
            // Invalid IPN transaction.  Check the log for details. 
            $this->last_error = 'IPN Validation Failed.'; 
            $this->log_ipn_results(false);     
            return false; 
        } 
    } 
 
    function log_ipn_results($success){ 
        if (!$this->ipn_log) return;  // is logging turned off? 
 
        // Timestamp 
        $text = '['.date('m/d/Y g:i A').'] - ';  
 
        // Success or failure being logged? 
        if ($success) $text .= "SUCCESS!\n"; 
        else $text .= 'FAIL: '.$this->last_error."\n"; 
 
        // Log the POST variables 
        $text .= "IPN POST Vars from Paypal:\n"; 
        foreach ($this->ipn_data as $key=>$value) 
            $text .= "$key=$value, "; 
 
        // Log the response from the paypal server 
        $text .= "\nIPN Response from Paypal Server:\n ".$this->ipn_response; 
 
        // Write to log 
        $fp=fopen($this->ipn_log_file,'a'); 
        fwrite($fp, $text . "\n\n");  
 
        fclose($fp);  // close file 
    } 
 
    function dump(){ 
        // Used for debugging, this function will output all the field/value pairs 
        // that are currently defined in the instance of the class using the 
        // add_field() function. 
        ksort($this->fields); 
        echo '<h2>ppal->dump() Output:</h2>' . "\n"; 
        echo '<code style="font: 12px Monaco, \'Courier New\', Verdana, Sans-serif;  background: #f9f9f9; border: 1px solid #D0D0D0; color: #002166; display: block; margin: 14px 0; padding: 12px 10px;">' . "\n"; 
        foreach ($this->fields as $key => $value) echo '<strong>'. $key .'</strong>:    '. urldecode($value) .'<br/>'; 
        echo "</code>\n"; 
    } 
     
    function curlPost($paypal_url, $paypal_return_arr){ 
        $req = 'cmd=_notify-validate'; 
        foreach($paypal_return_arr as $key => $value){ 
            $value = urlencode(stripslashes($value)); 
            $req .= "&$key=$value"; 
        } 
             
        $ipn_site_url = $paypal_url; 
        $ch = curl_init(); 
        curl_setopt($ch, CURLOPT_URL, $ipn_site_url); 
        curl_setopt($ch, CURLOPT_HEADER, false); 
        curl_setopt($ch, CURLOPT_POST, 1); 
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
        curl_setopt($ch, CURLOPT_POSTFIELDS, $req); 
        $result = curl_exec($ch); 
        curl_close($ch); 
     
        return $result; 
    } 
 
}

<?php defined('BASEPATH') OR exit('No direct script access allowed'); 
 
class Products extends CI_Controller{ 
     
    function  __construct(){ 
        parent::__construct(); 
         
        // Load paypal library 
        $this->load->library('paypal_lib'); 
         
        // Load product model 
        $this->load->model('product'); 
    } 
     
    function index(){ 
        $data = array(); 
         
        // Get products from the database 
        $data['products'] = $this->product->getRows(); 
         
        // Pass product data to the view 
        $this->load->view('products/index', $data); 
    } 
     
    function buy($id){ 
        // Set variables for paypal form 
        $returnURL = base_url().'paypal/success'; //payment success url 
        $cancelURL = base_url().'paypal/cancel'; //payment cancel url 
        $notifyURL = base_url().'paypal/ipn'; //ipn url 
         
        // Get product data from the database 
        $product = $this->product->getRows($id); 
         
        // Get current user ID from the session (optional) 
        $userID = !empty($_SESSION['userID'])?$_SESSION['userID']:1; 
         
        // Add fields to paypal form 
        $this->paypal_lib->add_field('return', $returnURL); 
        $this->paypal_lib->add_field('cancel_return', $cancelURL); 
        $this->paypal_lib->add_field('notify_url', $notifyURL); 
        $this->paypal_lib->add_field('item_name', $product['name']); 
        $this->paypal_lib->add_field('custom', $userID); 
        $this->paypal_lib->add_field('item_number',  $product['id']); 
        $this->paypal_lib->add_field('amount',  $product['price']); 
         
        // Render paypal form 
        $this->paypal_lib->paypal_auto_form(); 
    } 
}

<?php defined('BASEPATH') OR exit('No direct script access allowed'); 
 
class Paypal extends CI_Controller{ 
     
     function  __construct(){ 
        parent::__construct(); 
         
        // Load paypal library 
        $this->load->library('paypal_lib'); 
         
        // Load product model 
        $this->load->model('product'); 
         
        // Load payment model 
        $this->load->model('payment'); 
     } 
      
    function success(){ 
        // Get the transaction data 
        $paypalInfo = $this->input->get(); 
         
        $productData = $paymentData = array(); 
        if(!empty($paypalInfo['item_number']) && !empty($paypalInfo['tx']) && !empty($paypalInfo['amt']) && !empty($paypalInfo['cc']) && !empty($paypalInfo['st'])){ 
            $item_name = $paypalInfo['item_name']; 
            $item_number = $paypalInfo['item_number']; 
            $txn_id = $paypalInfo["tx"]; 
            $payment_amt = $paypalInfo["amt"]; 
            $currency_code = $paypalInfo["cc"]; 
            $status = $paypalInfo["st"]; 
             
            // Get product info from the database 
            $productData = $this->product->getRows($item_number); 
             
            // Check if transaction data exists with the same TXN ID 
            $paymentData = $this->payment->getPayment(array('txn_id' => $txn_id)); 
        } 
         
        // Pass the transaction data to view 
        $data['product'] = $productData; 
        $data['payment'] = $paymentData; 
        $this->load->view('paypal/success', $data); 
    } 
      
     function cancel(){ 
        // Load payment failed view 
        $this->load->view('paypal/cancel'); 
     } 
      
     function ipn(){ 
        // Retrieve transaction data from PayPal IPN POST 
        $paypalInfo = $this->input->post(); 
         
        if(!empty($paypalInfo)){ 
            // Validate and get the ipn response 
            $ipnCheck = $this->paypal_lib->validate_ipn($paypalInfo); 
 
            // Check whether the transaction is valid 
            if($ipnCheck){ 
                // Check whether the transaction data is exists 
                $prevPayment = $this->payment->getPayment(array('txn_id' => $paypalInfo["txn_id"])); 
                if(!$prevPayment){ 
                    // Insert the transaction data in the database 
                    $data['user_id']    = $paypalInfo["custom"]; 
                    $data['product_id']    = $paypalInfo["item_number"]; 
                    $data['txn_id']    = $paypalInfo["txn_id"]; 
                    $data['payment_gross']    = $paypalInfo["mc_gross"]; 
                    $data['currency_code']    = $paypalInfo["mc_currency"]; 
                    $data['payer_name']    = trim($paypalInfo["first_name"].' '.$paypalInfo["last_name"], ' '); 
                    $data['payer_email']    = $paypalInfo["payer_email"]; 
                    $data['status'] = $paypalInfo["payment_status"]; 
     
                    $this->payment->insertTransaction($data); 
                } 
            } 
        } 
    } 
}

<?php defined('BASEPATH') OR exit('No direct script access allowed'); 
 
class Product extends CI_Model{ 
     
    function __construct() { 
        $this->proTable   = 'products'; 
    } 
     
    /* 
     * Fetch products data from the database 
     * @param id returns a single record if specified, otherwise all records 
     */ 
    public function getRows($id = ''){ 
        $this->db->select('*'); 
        $this->db->from($this->proTable); 
        $this->db->where('status', '1'); 
        if($id){ 
            $this->db->where('id', $id); 
            $query = $this->db->get(); 
            $result = $query->row_array(); 
        }else{ 
            $this->db->order_by('name', 'asc'); 
            $query = $this->db->get(); 
            $result = $query->result_array(); 
        } 
         
        // return fetched data 
        return !empty($result)?$result:false; 
    } 
     
}

<?php defined('BASEPATH') OR exit('No direct script access allowed'); 
 
class Payment extends CI_Model{ 
     
    function __construct() { 
        $this->transTable = 'payments'; 
    } 
     
    /* 
     * Fetch payment data from the database 
     * @param id returns a single record if specified, otherwise all records 
     */ 
    public function getPayment($conditions = array()){ 
        $this->db->select('*'); 
        $this->db->from($this->transTable); 
         
        if(!empty($conditions)){ 
            foreach($conditions as $key=>$val){ 
                $this->db->where($key, $val); 
            } 
        } 
         
        $result = $this->db->get(); 
        return ($result->num_rows() > 0)?$result->row_array():false; 
    } 
     
    /* 
     * Insert payment data in the database 
     * @param data array 
     */ 
    public function insertTransaction($data){ 
        $insert = $this->db->insert($this->transTable,$data); 
        return $insert?true:false; 
    } 
     
}

<!-- List all products -->
<?php if(!empty($products)){ foreach($products as $row){ ?>
    <div class="card">
        <img src="<?php echo base_url('assets/images/'.$row['image']); ?>" />
        <div class="card-body">
            <h5 class="card-title"><?php echo $row['name']; ?></h5>
            <p class="card-text">Lorem Ipsum is simply dummy text of the printing and typesetting industry.</p>
            <h6>$<?php echo $row['price'].' '.$row['currency']; ?></h6>
            <a href="<?php echo base_url('products/buy/'.$row['id']); ?>" class="btn"><img src="<?php echo base_url('assets/images/paypal-btn.png'); ?>" /></a>
        </div>
    </div>
<?php } }else{ ?>
    <p>Product(s) not found...</p>
<?php } ?>

<?php if(!empty($payment)){ ?>
    <h1 class="success">Your Payment has been Successful!</h1>
    <h4>Payment Information</h4>
    <p><b>Reference Number:</b> #<?php echo $payment['id']; ?></p>
    <p><b>Transaction ID:</b> <?php echo $payment['txn_id']; ?></p>
    <p><b>Paid Amount:</b> <?php echo $payment['payment_gross'].' '.$payment['currency_code']; ?></p>
    <p><b>Payment Status:</b> <?php echo $payment['status']; ?></p>
	
    <h4>Payer Information</h4>
    <p><b>Name:</b> <?php echo $payment['payer_name']; ?></p>
    <p><b>Email:</b> <?php echo $payment['payer_email']; ?></p>
	
    <h4>Product Information</h4>
    <p><b>Name:</b> <?php echo $product['name']; ?></p>
    <p><b>Price:</b> <?php echo $product['price'].' '.$product['currency']; ?></p>
<?php }else{ ?>
    <h1 class="error">Transaction has been failed!</h1>
<?php } ?>

<div class="status">
    <h1 class="error">Your transaction was canceled!</h1>
</div>