[Wiki] PayPal Payment And IPN (Instant Payment Notification)

// Define LIVE constant as true if 'localhost' is not present in the host name. Configure the detecting of environment as necessary of course.
defined('LIVE') || define('LIVE', substr($_SERVER['HTTP_HOST'],'localhost')===false ? false : true);
if (LIVE) {
  define('PAYPAL_SANDBOX',false);
  define('PAYPAL_HOST', 'ipnpb.paypal.com');
  define('PAYPAL_URL', 'https://ipnpb.paypal.com/cgi-bin/webscr');
  define('PAYPAL_EMAIL',''); // live email of merchant
}else{
  define('PAYPAL_HOST', 'www.sandbox.paypal.com');
  define('PAYPAL_URL', 'https://www.sandbox.paypal.com/uk/cgi-bin/webscr');
  define('PAYPAL_EMAIL', ''); // dev email of merchant
  define('PAYPAL_SANDBOX',true);
}

<div class="form">
<?php
    $form=$this->beginWidget('CActiveForm', array(
        'id'=>'orderForm',
        'htmlOptions'=>array('onsubmit'=>'return false;')
    ));
    // paypal fields
    echo CHtml::hiddenField('cmd','_cart');
    echo CHtml::hiddenField('upload','1');
    echo CHtml::hiddenField('currency_code','EUR'); // enter currency
    echo CHtml::hiddenField('business',PAYPAL_EMAIL);
// set up path to successful order
    echo CHtml::hiddenField('return',Yii::app()->getRequest()->getBaseUrl(true).'order/success');
// set up url to cancel order
    echo CHtml::hiddenField('cancel_return',Yii::app()->getRequest()->getBaseUrl(true).'order/canceled');
// set up path to paypal IPN listener
    echo CHtml::hiddenField('notify_url',Yii::app()->getRequest()->getBaseUrl(true).'order/paypalNotify');
    echo CHtml::hiddenField('item_name_1',$productLang->title); // product title goes here
    echo CHtml::hiddenField('quantity_1','',array('id'=>'paypalQty'));
    echo CHtml::hiddenField('amount_1','',array('id'=>'paypalPrice'));
    echo CHtml::hiddenField('custom','',array('id'=>'paypalOrderId')); // here we will set order id after we create the order via ajax
    echo CHtml::hiddenField('charset','utf-8');
    // order fields
    echo CHtml::hiddenField('currencyCode','EUR'); // currency code
    echo CHtml::submitButton('',array('style'=>'display:none;'));
?>
    <div class="note">Fields with asterisk are required<span class="required">*</span></div>
    <?php echo $form->errorSummary($model); ?>
 
    <div class="row indent-bot5">
        <?php echo $form->labelEx($model,'qty'); ?>
        <?php echo $form->textField($model,'qty',array('size'=>4)); ?>
        <?php echo $form->error($model,'qty'); ?>
    </div>
 
    <div class="row indent-bot5">
        <h2 class="strong">Price: <span id="singlePrice"><?php echo $product->price // model product with property price ?> EURO</span></h2>
    </div>
 
    <div class="row indent-bot5">
        <h2 class="strong">Total: <span id="totalPriceTxt"><?php echo $product->price?></span> EURO</h2>
    </div>
 
    <div class="row indent-bot5">
        <?php // set path to paypal button image
 echo CHtml::imageButton(bu('images/paypalButton.png'),array('id'=>'paypalBtn','name'=>'paypalBtn',
            'onclick'=>'createOrder(this);'))?>
    </div>
 
<?php $this->endWidget(); ?>
</div>
<script type="text/javascript">
    $(function(){
        setTotalPrice();
        $('#Order_qty').keyup(function(){
            setTotalPrice();
        });
    });
 
    function setTotalPrice(){
        var qty=parseInt($('#Order_qty').val(),10);
        qty = isNaN(qty) ? 0 : qty;
        $('#paypalQty').val(qty);
        var totalPrice = qty * parseFloat($('#singlePrice').html());
        $('#paypalPrice').val(totalPrice);
        $('#totalPriceTxt').html(totalPrice);
        $('#Order_total').val(totalPrice);
    }
 
    // create db record in tbl order, update paypalPrice field and submit the form
    function createOrder(btn,totalPrice,action){
        var requiredFields = ['qty']; // enter more required fields (field with id="Order_qty" will be checked for value)
        var error = false;
        $.each(requiredFields, function(key, field) {
            if($('#Order_'+field).val()===''){
                error = true;
                alert('Please fill out all required fields.');
                return false;
            }
        });
        if (error)
            return false;
        if($('#Order_qty').val() > <?php echo $product->qty?>){
            alert('<?php echo Exceeding available quantity. We are sorry for the inconvenience.'); // assuming we have property qty in model $product
            return;
        }
 
// OrderController needs to create a record in tbl order and return response in JSON format (in this case) use json_encode for example if your PHP version supports this function
        $.post(Yii::app()->getRequest()->getBaseUrl().'order/create'; ?>',$('#orderForm').serializeArray(),function(orderResp) {
            if(orderResp.error === undefined){
                var action;
                $('#paypalOrderId').val(orderResp.id);
                $('#orderForm').attr({action:'<?php echo PAYPAL_URL?>',onsubmit:true}).submit();
            }else{
                alert(orderResp.error);
            }
        },'json');
    }
</script>

public function actionPaypalNotify(){
    $paypal = new PayPal();
    $paypal->notify();
}

class PayPal {
 
    public function notify(){
        $logCat = 'paypal';
        $listener = new IpnListener();
        $listener->use_sandbox = PAYPAL_SANDBOX;
        try {
            $listener->requirePostMethod();
            if ($listener->processIpn() && $_POST['payment_status']==='Completed') {
                $order = Order::model()->findByPk($_POST['custom']); // we set custom as our order id on sending the request to paypal
                if ($order === null) {
                    Yii::log('Cannot find order with id ' . $custom, CLogger::LEVEL_ERROR, $logCat);
                    Yii::app()->end(); // note that die; will not execute Yii::log() so we have to use Yii::app()->end();
                }
                $order->setAttributes(array(
                    'payDate'=>date('Y-m-d H:m:i'), // payDate field in model Order
                    'statusId'=>Order::STATUS_PAID // statusId field in model Order
                ));
                $order->save();
                Product::deductQty($order); // deduct quantity for this product
                Product::sendSuccessEmails($order); // send success emails to merchant and buyer
            }else{
                Yii::log('invalid ipn', CLogger::LEVEL_ERROR, $logCat);
            }
        } catch (Exception $e) {
            Yii::log($e->getMessage(), CLogger::LEVEL_ERROR, $logCat);
        }
    }
 
}

class Order extends CActiveRecord
{
    const STATUS_INITIATED = 1;
    const STATUS_CANCELED = 2;
    const STATUS_EXPIRED = 3;
    const STATUS_PAID = 4;
    public $statuses = array(
        self::STATUS_INITIATED => 'Initiated',
        self::STATUS_CANCELED => 'Canceled',
        self::STATUS_EXPIRED => 'Expired',
        self::STATUS_PAID => 'Paid',
    );
// more code of Order model