The last week was a tough week, I was interested to integrate my PayPal module to the new e-commerce project but when I started many problems hitting my face, which makes me think to read PayPal API documentation again, once I did this, I understood what's happening exactly.

UPDATE 09/10/2018

Jay Patel
Hey guys, this is a very good starting point for a paypal integration. However, I found some tiny issues with the code.

1. You should NOT use `sample/bootstrap.php` file. It is as the name suggest, for Sample use only. You can however, use the instructions mentioned here to initialize. https://github.com/paypal/PayPal-PHP-SDK/wiki/Making-First-Call

2. You could use `$payment->getApprovalLink()` on payment create success instead of iterating through it. Not a big deal however using either way.

3. When `execute` call is made you forgot to catch that exception. You should have a similar try catch block as you had for create, and make sure you return false, if for any reason your execute call fails. Note: I am one of the contributor to that library, but consider this comment as a person opinion and not from PayPal. I want to make sure people realize the difference here. I am just trying to help fellow developers get access to better knowledge. Also, checkout the shiny new 2.0-beta version of the SDK. It has solved a lot of problem for you. Made it extremely easy to use, and is almost ready for production release.

PayPal Payment Getaways Types :

It's about two years ago I haven’t updated PayPal module, but on the other side PayPal made many changes with payment gateways which by logic reflect API SDK, so I specified some hours to figure out what going on, because my client asked me to select the appropriate payment getaway, after couple of hours I figured that PayPal now has three payment getaways:

1- PayPal Express Checkout

Which give a merchants the ability to sell for all buyers who have PayPal account, so if your customer hasn’t PayPal account he should create one ،otherwise he couldn’t complete the purchasing process.

2- PayPal Payment Standard

While , this gateway allow buyers to choose between two payment methods (PayPal) or (credit card), this seems very helpful for non-PayPal users, and very effective for increasing payments number, because many clients was lazy, they always have no time to fill a  registration form with Their details.

The second interested property for the credit card payment, that PayPal offers that payment on Their site not yours, so when the user hits the buy button it will redirect to PayPal paying page which appears two choices (use PayPal account-user credit card), this would be a good choice for anyone prefer to jumps over potential security issues and let take care of that, to just focus on his product.

Another interesting benefits I figured, it's a free getaway, there's no monthly or annually fees, also it is no restrictions or limits for using in any country because it's available for every country PayPal available in.

3- PayPal Payment Pro.

This gateway like what named for, it's for professional usage, your clients could pay with PayPal account or credit card but this time the whole process will be on your site which called (direct payment),but unfortunately this option only allowed for limited counties, also you should pay about $30 as a monthly fee.

This is the short story, and I liked to keep it simple for anyone who wants to know about the three payment getaways quickly but if you want to read more I suggest to read a PayPal documentation.

Now let's give a full example for how to integrate PayPal SDK with Codeigniter ?

The example will cover the whole process from clicking the buy button to insert the response into payments tables, and it will only focus for the PayPal payment standard because I have not seen any updated tutorial that cover this getaway until now with the Payments REST API, let's do it dude

PayPal Integration Steps :

1-Create sandbox account, then create a new app to get api paypal credential from your sandbox to test,you can follow steps in this Guide and get paypal credential

2-Create Paypal.php file, place it into application/config directory, you can replace client_id

And secret with your paypal credential or copy paste this code as it is (but remember to change it when your project go to the production phase also change the mode)

<?php
/** set your paypal credential **/

$config['client_id'] = 'AYSq3RDGsmBLJE-otTkBtM-jBRd1TCQwFf9RGfwddNXWz0uFU9ztymylOhRS';
$config['secret'] = 'EGnHDxD_qRPdaLdZz8iCr8N7_MzF-YHPTkjs6NKYQvQSBngp4PTTVWkPZRbL';

/**
 * SDK configuration
 */
/**
 * Available option 'sandbox' or 'live'
 */
$config['settings'] = array(

    'mode' => 'sandbox',
    /**
     * Specify the max request time in seconds
     */
    'http.ConnectionTimeOut' => 1000,
    /**
     * Whether want to log to a file
     */
    'log.LogEnabled' => true,
    /**
     * Specify the file that want to write on
     */
    'log.FileName' => 'application/logs/paypal.log',
    /**
     * Available option 'FINE', 'INFO', 'WARN' or 'ERROR'
     *
     * Logging is most verbose in the 'FINE' level and decreases as you
     * proceed towards ERROR
     */
    'log.LogLevel' => 'FINE'
);

3-Download paypal sdk zip file from here, extract and place rest-api-sdk-php directory into application/libraries

4-Create PayPal.php controller and copy paste this code

<?php if (!defined('BASEPATH')) exit('No direct script access allowed');

require_once(APPPATH . 'libraries/paypal-php-sdk/paypal/rest-api-sdk-php/sample/bootstrap.php'); // require paypal files

use PayPal\Api\ItemList;
use PayPal\Api\Payment;
use PayPal\Api\RedirectUrls;
use PayPal\Api\PaymentExecution;

class Paypal extends CI_Controller
{
    public $_api_context;

    function  __construct()
    {
        parent::__construct();
        $this->load->model('paypal_model', 'paypal');
        // paypal credentials
        $this->config->load('paypal');

        $this->_api_context = new \PayPal\Rest\ApiContext(
            new \PayPal\Auth\OAuthTokenCredential(
                $this->config->item('client_id'), $this->config->item('secret')
            )
        );
    }

    function index(){
        $this->load->view('content/payment_credit_form');
    }


    function create_payment_with_paypal()
    {

        // setup PayPal api context
        $this->_api_context->setConfig($this->config->item('settings'));


// ### Payer
// A resource representing a Payer that funds a payment
// For direct credit card payments, set payment method
// to 'credit_card' and add an array of funding instruments.

        $payer['payment_method'] = 'paypal';

// ### Itemized information
// (Optional) Lets you specify item wise
// information
        $item1["name"] = $this->input->post('item_name');
        $item1["sku"] = $this->input->post('item_number');  // Similar to `item_number` in Classic API
        $item1["description"] = $this->input->post('item_description');
        $item1["currency"] ="USD";
        $item1["quantity"] =1;
        $item1["price"] = $this->input->post('item_price');

        $itemList = new ItemList();
        $itemList->setItems(array($item1));

// ### Additional payment details
// Use this optional field to set additional
// payment information such as tax, shipping
// charges etc.
        $details['tax'] = $this->input->post('details_tax');
        $details['subtotal'] = $this->input->post('details_subtotal');
// ### Amount
// Lets you specify a payment amount.
// You can also specify additional details
// such as shipping, tax.
        $amount['currency'] = "USD";
        $amount['total'] = $details['tax'] + $details['subtotal'];
        $amount['details'] = $details;
// ### Transaction
// A transaction defines the contract of a
// payment - what is the payment for and who
// is fulfilling it.
        $transaction['description'] ='Payment description';
        $transaction['amount'] = $amount;
        $transaction['invoice_number'] = uniqid();
        $transaction['item_list'] = $itemList;

        // ### Redirect urls
// Set the urls that the buyer must be redirected to after
// payment approval/ cancellation.
        $baseUrl = base_url();
        $redirectUrls = new RedirectUrls();
        $redirectUrls->setReturnUrl($baseUrl."paypal/getPaymentStatus")
            ->setCancelUrl($baseUrl."paypal/getPaymentStatus");

// ### Payment
// A Payment Resource; create one using
// the above types and intent set to sale 'sale'
        $payment = new Payment();
        $payment->setIntent("sale")
            ->setPayer($payer)
            ->setRedirectUrls($redirectUrls)
            ->setTransactions(array($transaction));

        try {
            $payment->create($this->_api_context);
        } catch (Exception $ex) {
            // NOTE: PLEASE DO NOT USE RESULTPRINTER CLASS IN YOUR ORIGINAL CODE. FOR SAMPLE ONLY
            ResultPrinter::printError("Created Payment Using PayPal. Please visit the URL to Approve.", "Payment", null, $ex);
            exit(1);
        }
        foreach($payment->getLinks() as $link) {
            if($link->getRel() == 'approval_url') {
                $redirect_url = $link->getHref();
                break;
            }
        }

        if(isset($redirect_url)) {
            /** redirect to paypal **/
            redirect($redirect_url);
        }

        $this->session->set_flashdata('success_msg','Unknown error occurred');
        redirect('paypal/index');

    }


    public function getPaymentStatus()
    {

        // paypal credentials

        /** Get the payment ID before session clear **/
        $payment_id = $this->input->get("paymentId") ;
        $PayerID = $this->input->get("PayerID") ;
        $token = $this->input->get("token") ;
        /** clear the session payment ID **/

        if (empty($PayerID) || empty($token)) {
            $this->session->set_flashdata('success_msg','Payment failed');
            redirect('paypal/index');
        }

        $payment = Payment::get($payment_id,$this->_api_context);


        /** PaymentExecution object includes information necessary **/
        /** to execute a PayPal account payment. **/
        /** The payer_id is added to the request query parameters **/
        /** when the user is redirected from paypal back to your site **/
        $execution = new PaymentExecution();
        $execution->setPayerId($this->input->get('PayerID'));

        /**Execute the payment **/
        $result = $payment->execute($execution,$this->_api_context);



        //  DEBUG RESULT, remove it later **/
        if ($result->getState() == 'approved') {
            $trans = $result->getTransactions();

            // item info
            $Subtotal = $trans[0]->getAmount()->getDetails()->getSubtotal();
            $Tax = $trans[0]->getAmount()->getDetails()->getTax();

            $payer = $result->getPayer();
            // payer info //
            $PaymentMethod =$payer->getPaymentMethod();
            $PayerStatus =$payer->getStatus();
            $PayerMail =$payer->getPayerInfo()->getEmail();

            $relatedResources = $trans[0]->getRelatedResources();
            $sale = $relatedResources[0]->getSale();
            // sale info //
            $saleId = $sale->getId();
            $CreateTime = $sale->getCreateTime();
            $UpdateTime = $sale->getUpdateTime();
            $State = $sale->getState();
            $Total = $sale->getAmount()->getTotal();
            /** it's all right **/
            /** Here Write your database logic like that insert record or value in database if you want **/
            $this->paypal->create($Total,$Subtotal,$Tax,$PaymentMethod,$PayerStatus,$PayerMail,$saleId,$CreateTime,$UpdateTime,$State);
            $this->session->set_flashdata('success_msg','Payment success');
            redirect('paypal/success');
        }
        $this->session->set_flashdata('success_msg','Payment failed');
        redirect('paypal/cancel');
    }
    function success(){
        $this->load->view("content/success");
    }
    function cancel(){
        $this->paypal->create_payment();
        $this->load->view("content/cancel");
    }
}

5-Create paypel_model.php and copy paste this code

<?php

if (!defined('BASEPATH'))
	exit('No direct script access allowed');

class Paypal_model extends CI_Model {

	function __construct() {
		parent::__construct();
	}

	/* This function create new Service. */

	function create($Total,$SubTotal,$Tax,$PaymentMethod,$PayerStatus,$PayerMail,$saleId,$CreateTime,$UpdateTime,$State) {
        $this->db->set('txn_id',$saleId);
        $this->db->set('PaymentMethod',$PaymentMethod);
        $this->db->set('PayerStatus',$PayerStatus);
        $this->db->set('PayerMail',$PayerMail);
        $this->db->set('Total',$Total);
        $this->db->set('SubTotal',$SubTotal);
        $this->db->set('Tax',$Tax);
        $this->db->set('Payment_state',$State);
		$this->db->set('CreateTime',$CreateTime);
		$this->db->set('UpdateTime',$UpdateTime);
		$this->db->insert('payments');
		$id = $this->db->insert_id();
		return $id;
	}

}

6-Create buy_form.php, success.php, cancel.php and place them into application/views, copy paste this code.

/////////////////// the buy form file //////////////////  
      <div class="container">

            <div class="starter-template">
                <h1>PayPal Payment</h1>
                <p class="lead">Pay Now</p>
            </div>

            <div class="contact-form">

                <p class="notice error"><?= $this->session->flashdata('error_msg') ?></p><br/>
                <p class="notice error"><?= $this->session->flashdata('success_msg') ?></p><br/>

                <form method="post" class="form-horizontal" role="form" action="<?= base_url() ?>paypal/create_payment_with_paypal">
                    <fieldset>
                        <input title="item_name" name="item_name" type="hidden" value="ahmed fakhr">
                        <input title="item_number" name="item_number" type="hidden" value="12345">
                        <input title="item_description" name="item_description" type="hidden" value="to buy samsung smart tv">
                        <input title="item_tax" name="item_tax" type="hidden" value="1">
                        <input title="item_price" name="item_price" type="hidden" value="7">
                        <input title="details_tax" name="details_tax" type="hidden" value="7">
                        <input title="details_subtotal" name="details_subtotal" type="hidden" value="7">

                        <div class="form-group">
                            <div class="col-sm-offset-5">
                                <button  type="submit"  class="btn btn-success">Pay Now</button>
                            </div>
                        </div>
                    </fieldset>
                </form>
            </div>
        </div><!-- /.container -->


////////////////// the success view file /////////////////  

    <div class="starter-template">
        <h1>PayPal Payment</h1>
        <p class="lead">Success</p>
    </div>

    <div class="contact-form">
        <div>
            <h2 style="font-family: 'quicksandbold'; font-size:16px; color:#313131; padding-bottom:8px;">Dear Member</h2>
            <span style="color: #646464;">Your payment was successful, thank you for purchase.</span><br/>
        </div>
    </div>
</div><!-- /.container -->



//////////////// the cancel view file ///////////

<div class="container">

    <div class="starter-template">
        <h1>PayPal Payment</h1>
        <p class="lead">Canceld order</p>
    </div>

    <div class="contact-form">

        <div>
            <h3 style="font-family: 'quicksandbold'; font-size:16px; color:#313131; padding-bottom:8px;">Dear Member</h3>
            <span style="color:#D70000; font-size:16px; font-weight:bold;">We are sorry! Your last transaction was cancelled.</span>
        </div>
    </div>
</div><!-- /.container -->

7-Create payments transactions table to save payment on this table

--
-- Database: `demo`
--

-- --------------------------------------------------------

--
-- Table structure for table `payments`
--

CREATE TABLE `payments` (
  `txn_id` int(11) NOT NULL,
  `PaymentMethod` varchar(50) NOT NULL,
  `PayerStatus` varchar(50) NOT NULL,
  `PayerMail` int(100) NOT NULL,
  `Total` decimal(19,2) NOT NULL,
  `SubTotal` decimal(19,2) NOT NULL,
  `Tax` decimal(19,2) NOT NULL,
  `Payment_state` varchar(50) NOT NULL,
  `CreateTime` varchar(50) NOT NULL,
  `UpdateTime` varchar(50) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

8-Go to this URL to start the demo http://localhost/project_name/paypal

What happen in the demo scenario ?

1-After going to paypal/index function the buy form will appear

2-When click pay now you will redirect to PayPal sandbox by using create_payment_with_paypal function and you will see payment page with two choices, if you have a paypal account then login, if not click (Pay with Debit or Credit Card) button.

3-After login with email and password for your PayPal account you will see payment details page, you have two choices, to click continue button and complete the order or click cancel button to cancel the order.

4-When you click continue you will redirect to getPaymentStatus function, this function will detect the current payment method state if it is approved then it will collect payment details and send it to create function to insert into payments tables, then redirect to success function to see success message, or to cancel function to see cancel message

Conclusion

I hope this help you to understand PayPal API and save your time as possible, and I will continue to update this tutorial to follow PayPal updates as possible.

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