zen-cart进入第三方支付网站后，如果不能正常返回，则会造成客户已付款但后台却无订单数据的尴尬局面。本文就针对该问题给出一种解决方案，希望对被同样问题困扰的同行有所帮助。

用过zen-cart的人都知道，zen-cart中下单步骤是下面这样的(其中[]中的表示不是必须的)：

   1. 购物车(shopping cart)

   2. [货运方式(delivery method)]

   3. 支付方式(payment method)

   4. 订单确认(confirmation)

   5. [第三方网站支付]

   6. 订单处理(checkout process)――这一步比较重要，因为会在这里将购物车中的信息写入订单

   7. 下单成功(checkout success)

   这样的流程在正常情况下是没有任何问题的。但是，从第5步到第6部的过程中，用户可能以为付款成功就直接关闭掉网页了，或者由于网络原因造成不能正常跳转到checkout_process页面，这样造成的后果是很严重的，因为订单不能被正常的创建。

   基于上述的分析， 我们希望稍微地改变一下流程，即在支付之前订单已经创建好了，这样就算在支付时不能从第三方支付网站跳转回来，我们也不会存在用户付款成功却在后台没有订单的情况了。经过修改后的蓝图基本是下面这样的：

   1. 在checkour_confirmation页面确认订单后，都会直接proccess，并且进入checkour_success页面,可以在这里进入付款页面。如下图所示：

    

   2. 如果当时客户没能付款，也可进入自己的后台对历史订单进行付款。如下图所示：

    

   下面我们就来看看如何一步一步来实现上述的功能。

  1. 首先我们需要对现有的支付模块进行一个改造。需要对支付方式的class增加一个字段paynow_action_url，用来表示进行支付的页面url，另外还需要增加一个函数，paynow_button($order_id)，来获取支付表单的参数隐藏域代码。
要增加paynow_action_url字段，请在类payment的构造函数中最后加上下面的代码：

 
if ( (zen_not_null($module)) && (in_array($module.'.php', $this->modules)) && (isset($GLOBALS[$module]->paynow_action_url)) ) { 
$this->paynow_action_url = $GLOBALS[$module]->paynow_action_url; 
} 

要增加paynow_button($order_id)函数，请在payment类的最后一个函数之后加上如下的代码：

 
function paynow_button($order_id){ 
if (is_array($this->modules)) { 
if (is_object($GLOBALS[$this->selected_module])) { 
return $GLOBALS[$this->selected_module]->paynow_button($order_id); 
} 
} 
} 

2. 以paypal支付方式为例子，说明如何具体实现。为了不破坏paypal原有的代码，我们将paypal.php文件拷贝一个副本出来，并命名为paypalsimple.php，并对里面的代码做适当的修改。代码如下所示，可以看到，这里去掉了对form_action_url的指定，并给定了paynow_action_url，因为我们希望用户点击“确认订单”后直接进入checkout_process，所以如果不指定form_action_url，那么确认订单的表单就会直接提交到checkout_process页面了，而paynow_action_url就是以前的form_action_url的值。paynow_button函数的实现也很简单，这里只是将原先的process_button()函数的内容剪切过来而已，只不过我们没有使用全局的$order变量，而是使用$order = new order($order_id),来重新构造的一个对象，这样做是为在历史订单中显示pay now按钮做准备的。
paypalsimple.php

 
<?php 
/** 
* @package paypalsimple payment module 
* @copyright Copyright 2003-2006 Zen Cart Development Team 
* @copyright Portions Copyright 2003 osCommerce 
* @license http://www.zen-cart.com/license/2_0.txt GNU Public License V2.0 
* @version $Id: paypalsimple.php 4960 2009-12-29 11:46:46Z gary $ 
*/ 
// ensure dependencies are loaded 
include_once((IS_ADMIN_FLAG === true ? DIR_FS_CATALOG_MODULES : DIR_WS_MODULES) . 'payment/paypal/paypal_functions.php'); 
class paypalsimple { 
var $code, $title, $description, $enabled; 
// class constructor 
function paypalsimple() { 
global $order; 
$this->code = 'paypalsimple'; 
$this->title = MODULE_PAYMENT_PAYPAL_SIMPLE_TEXT_TITLE; 
if(IS_ADMIN_FLAG === true){ 
$this->title = MODULE_PAYMENT_PAYPAL_SIMPLE_TEXT_ADMIN_TITLE; 
} 
$this->description = MODULE_PAYMENT_PAYPAL_SIMPLE_TEXT_DESCRIPTION; 
$this->sort_order = MODULE_PAYMENT_PAYPAL_SIMPLE_SORT_ORDER; 
$this->enabled = ((MODULE_PAYMENT_PAYPAL_SIMPLE_STATUS == 'True') ? true : false); 
if ((int)MODULE_PAYMENT_PAYPAL_SIMPLE_ORDER_STATUS_ID > 0) { 
$this->order_status = MODULE_PAYMENT_PAYPAL_SIMPLE_ORDER_STATUS_ID; 
} 
$this->paynow_action_url = 'https://' . MODULE_PAYMENT_PAYPAL_SIMPLE_HANDLER; 
if (is_object($order)) $this->update_status(); 
} 
// class methods 
function update_status() { 
global $order, $db; 
if ( ($this->enabled == true) && ((int)MODULE_PAYMENT_PAYPAL_SIMPLE_ZONE > 0) ) { 
$check_flag = false; 
$check = $db->Execute("select zone_id from " . TABLE_ZONES_TO_GEO_ZONES . " where geo_zone_id = '" . MODULE_PAYMENT_PAYPAL_SIMPLE_ZONE . "' and zone_country_id = '" . $order->billing['country']['id'] . "' order by zone_id"); 
while (!$check->EOF) { 
if ($check->fields['zone_id'] < 1) { 
$check_flag = true; 
break; 
} elseif ($check->fields['zone_id'] == $order->billing['zone_id']) { 
$check_flag = true; 
break; 
} 
$check->MoveNext(); 
} 
if ($check_flag == false) { 
$this->enabled = false; 
} 
} 
} 
function javascript_validation() { 
return false; 
} 
function selection() { 
$text = MODULE_PAYMENT_SIMPLE_PAYPAL_TEXT_CATALOG_LOGO.'  '.MODULE_PAYMENT_PAYPAL_SIMPLE_TEXT_TITLE . '<br/><br/>    <span class="smallText">' . MODULE_PAYMENT_PAYPAL_SIMPLE_ACCEPTANCE_MARK_TEXT . '</span><br/><br/>'; 
return array('id' => $this->code, 
'module' => $text 
); 
} 
function pre_confirmation_check() { 
return false; 
} 
function confirmation() { 
return false; 
} 
function process_button() { 
return false; 
} 
function before_process() { 
return false; 
} 
function after_process() { 
return false; 
} 
function get_error() { 
return false; 
} 
function check() { 
global $db; 
if (!isset($this->_check)) { 
$check_query = $db->Execute("select configuration_value from " . TABLE_CONFIGURATION . " where configuration_key = 'MODULE_PAYMENT_PAYPAL_SIMPLE_STATUS'"); 
$this->_check = $check_query->RecordCount(); 
} 
return $this->_check; 
} 
function install() { 
global $db; 
$db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, set_function, date_added) values ('Enable PayPal-Simple Module', 'MODULE_PAYMENT_PAYPAL_SIMPLE_STATUS', 'True', 'Do you want to accept PayPal-Simple payments?', '6', '0', 'zen_cfg_select_option(array(\'True\', \'False\'), ', now())"); 
$db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, date_added) values ('Sort order of display.', 'MODULE_PAYMENT_PAYPAL_SIMPLE_SORT_ORDER', '0', 'Sort order of display. Lowest is displayed first.', '6', '8', now())"); 
$db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, use_function, set_function, date_added) values ('Payment Zone', 'MODULE_PAYMENT_PAYPAL_SIMPLE_ZONE', '0', 'If a zone is selected, only enable this payment method for that zone.', '6', '2', 'zen_get_zone_class_title', 'zen_cfg_pull_down_zone_classes(', now())"); 
$db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, set_function, use_function, date_added) values ('Set Order Status', 'MODULE_PAYMENT_PAYPAL_SIMPLE_ORDER_STATUS_ID', '0', 'Set the status of orders made with this payment module to this value', '6', '0', 'zen_cfg_pull_down_order_statuses(', 'zen_get_order_status_name', now())"); 
$db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, set_function, date_added) values ('Mode for PayPal web services<br /><br />Default:<br /><code>www.paypal.com/cgi-bin/webscr</code><br />or<br /><code>www.paypal.com/us/cgi-bin/webscr</code><br />or for the UK,<br /><code>www.paypal.com/uk/cgi-bin/webscr</code>', 'MODULE_PAYMENT_PAYPAL_SIMPLE_HANDLER', 'www.paypal.com/cgi-bin/webscr', 'Choose the URL for PayPal live processing', '6', '73', '', now())"); 
} 
function remove() { 
global $db; 
$db->Execute("delete from " . TABLE_CONFIGURATION . " where configuration_key in ('" . implode("', '", $this->keys()) . "')"); 
} 
function keys() { 
return array('MODULE_PAYMENT_PAYPAL_SIMPLE_STATUS','MODULE_PAYMENT_PAYPAL_SIMPLE_SORT_ORDER','MODULE_PAYMENT_PAYPAL_SIMPLE_ZONE','MODULE_PAYMENT_PAYPAL_SIMPLE_ORDER_STATUS_ID', 'MODULE_PAYMENT_PAYPAL_SIMPLE_HANDLER'); 
} 
function paynow_button($order_id){ 
global $db, $order, $currencies, $currency; 
require_once(DIR_WS_CLASSES . 'order.php'); 
$order = new order($order_id); 
$options = array(); 
$optionsCore = array(); 
$optionsPhone = array(); 
$optionsShip = array(); 
$optionsLineItems = array(); 
$optionsAggregate = array(); 
$optionsTrans = array(); 
$buttonArray = array(); 
$this->totalsum = $order->info['total']; 
// save the session stuff permanently in case paypal loses the session 
$_SESSION['ppipn_key_to_remove'] = session_id(); 
$db->Execute("delete from " . TABLE_PAYPAL_SESSION . " where session_id = '" . zen_db_input($_SESSION['ppipn_key_to_remove']) . "'"); 
$sql = "insert into " . TABLE_PAYPAL_SESSION . " (session_id, saved_session, expiry) values ( 
'" . zen_db_input($_SESSION['ppipn_key_to_remove']) . "', 
'" . base64_encode(serialize($_SESSION)) . "', 
'" . (time() + (1*60*60*24*2)) . "')"; 
$db->Execute($sql); 
$my_currency = select_pp_currency(); 
$this->transaction_currency = $my_currency; 
$this->transaction_amount = ($this->totalsum * $currencies->get_value($my_currency)); 
$telephone = preg_replace('/\D/', '', $order->customer['telephone']); 
if ($telephone != '') { 
$optionsPhone['H_PhoneNumber'] = $telephone; 
if (in_array($order->customer['country']['iso_code_2'], array('US','CA'))) { 
$optionsPhone['night_phone_a'] = substr($telephone,0,3); 
$optionsPhone['night_phone_b'] = substr($telephone,3,3); 
$optionsPhone['night_phone_c'] = substr($telephone,6,4); 
$optionsPhone['day_phone_a'] = substr($telephone,0,3); 
$optionsPhone['day_phone_b'] = substr($telephone,3,3); 
$optionsPhone['day_phone_c'] = substr($telephone,6,4); 
} else { 
$optionsPhone['night_phone_b'] = $telephone; 
$optionsPhone['day_phone_b'] = $telephone; 
} 
} 
$optionsCore = array( 
'charset' => CHARSET, 
'lc' => $order->customer['country']['iso_code_2'], 
'page_style' => MODULE_PAYMENT_PAYPAL_PAGE_STYLE, 
'custom' => zen_session_name() . '=' . zen_session_id(), 
'business' => MODULE_PAYMENT_PAYPAL_BUSINESS_ID, 
'return' => zen_href_link(FILENAME_PAY_SUCCESS, 'referer=paypal', 'SSL'), 
'cancel_return' => zen_href_link(FILENAME_PAY_FAILED, '', 'SSL'), 
'shopping_url' => zen_href_link(FILENAME_SHOPPING_CART, '', 'SSL'), 
'notify_url' => zen_href_link('ipn_main_handler.php', '', 'SSL',false,false,true), 
'redirect_cmd' => '_xclick', 
'rm' => 2, 
'bn' => 'zencart', 
'mrb' => 'R-6C7952342H795591R', 
'pal' => '9E82WJBKKGPLQ', 
); 
$optionsCust = array( 
'first_name' => replace_accents($order->customer['firstname']), 
'last_name' => replace_accents($order->customer['lastname']), 
'address1' => replace_accents($order->customer['street_address']), 
'city' => replace_accents($order->customer['city']), 
'state' => zen_get_zone_code($order->customer['country']['id'], $order->customer['zone_id'], $order->customer['zone_id']), 
'zip' => $order->customer['postcode'], 
'country' => $order->customer['country']['iso_code_2'], 
'email' => $order->customer['email_address'], 
); 
if ($order->customer['suburb'] != '') $optionsCust['address2'] = $order->customer['suburb']; 
if (MODULE_PAYMENT_PAYPAL_ADDRESS_REQUIRED == 2) $optionsCust = array( 
'address_name' => replace_accents($order->customer['firstname'] . ' ' . $order->customer['lastname']), 
'address_street' => replace_accents($order->customer['street_address']), 
'address_city' => replace_accents($order->customer['city']), 
'address_state' => zen_get_zone_code($order->customer['country']['id'], $order->customer['zone_id'], $order->customer['zone_id']), 
'address_zip' => $order->customer['postcode'], 
'address_country' => $order->customer['country']['title'], 
'address_country_code' => $order->customer['country']['iso_code_2'], 
'payer_email' => $order->customer['email_address'], 
); 
$optionsShip = array( 
//'address_override' => MODULE_PAYMENT_PAYPAL_ADDRESS_OVERRIDE, 
'no_shipping' => MODULE_PAYMENT_PAYPAL_ADDRESS_REQUIRED, 
); 
if (MODULE_PAYMENT_PAYPAL_DETAILED_CART == 'Yes') $optionsLineItems = ipn_getLineItemDetails(); 
if (sizeof($optionsLineItems) > 0) { 
$optionsLineItems['cmd'] = '_cart'; 
// $optionsLineItems['num_cart_items'] = sizeof($order->products); 
if (isset($optionsLineItems['shipping'])) { 
$optionsLineItems['shipping_1'] = $optionsLineItems['shipping']; 
unset($optionsLineItems['shipping']); 
} 
if (isset($optionsLineItems['handling'])) { 
$optionsLineItems['handling_1'] = $optionsLineItems['handling']; 
unset($optionsLineItems['handling']); 
} 
unset($optionsLineItems['subtotal']); 
// if line-item details couldn't be kept due to calculation mismatches or discounts etc, default to aggregate mode 
if (!isset($optionsLineItems['item_name_1'])) $optionsLineItems = array(); 
//if ($optionsLineItems['amount'] != $this->transaction_amount) $optionsLineItems = array(); 
ipn_debug_email('Line Item Details (if blank, this means there was a data mismatch, and thus bypassed): ' . "\n" . print_r($optionsLineItems, true)); 
} 
$products_name_display = ""; 
/* 
for ($i=0, $n=sizeof($order->products); $i<$n; $i++) { 
if(i > 0) { 
$products_name_display.= ', '; 
} 
$products_name_display.= $order->products[$i]['name']. '('. $order->products[$i]['qty'] .','.$order->products[$i]['dhisys_web_order_number'].')'; 
}*/ 
$optionsAggregate = array( 
'cmd' => '_ext-enter', 
'item_name' => $products_name_display, 
'item_number' => $order_id, 
'num_cart_items' => sizeof($order->products), 
'amount' => number_format($this->transaction_amount, $currencies->get_decimal_places($my_currency)), 
'shipping' => '0.00', 
); 
if (MODULE_PAYMENT_PAYPAL_TAX_OVERRIDE == 'true') $optionsAggregate['tax'] = '0.00'; 
if (MODULE_PAYMENT_PAYPAL_TAX_OVERRIDE == 'true') $optionsAggregate['tax_cart'] = '0.00'; 
$optionsTrans = array( 
'upload' => (int)(sizeof($order->products) > 0), 
'currency_code' => $my_currency, 
// 'paypal_order_id' => $paypal_order_id, 
//'no_note' => '1', 
//'invoice' => '', 
); 
// if line-item info is invalid, use aggregate: 
if (sizeof($optionsLineItems) > 0) $optionsAggregate = $optionsLineItems; 
// prepare submission 
$options = array_merge($optionsCore, $optionsCust, $optionsPhone, $optionsShip, $optionsTrans, $optionsAggregate); 
ipn_debug_email('Keys for submission: ' . print_r($options, true)); 
if(sizeof($order->products) > 0){ 
$options['cmd'] = '_cart'; 
for ($i=0, $n=sizeof($order->products); $i<$n; $i++) { 
$options['item_name_'. (string)($i+1)] = $order->products[$i]['name']; 
$options['item_number_'. (string)($i+1)] = $order->products[$i]['dhisys_web_order_number']; 
$options['amount_'. (string)($i+1)] = number_format((float)$order->products[$i]['final_price'],2); 
$options['quantity_'. (string)($i+1)] = $order->products[$i]['qty']; 
} 
} 
// build the button fields 
foreach ($options as $name => $value) { 
// remove quotation marks 
$value = str_replace('"', '', $value); 
// check for invalid chars 
if (preg_match('/[^a-zA-Z_0-9]/', $name)) { 
ipn_debug_email('datacheck - ABORTING - preg_match found invalid submission key: ' . $name . ' (' . $value . ')'); 
break; 
} 
// do we need special handling for & and = symbols? 
//if (strpos($value, '&') !== false || strpos($value, '=') !== false) $value = urlencode($value); 
$buttonArray[] = zen_draw_hidden_field($name, $value); 
} 
$_SESSION['paypal_transaction_info'] = array($this->transaction_amount, $this->transaction_currency); 
$process_button_string = implode("\n", $buttonArray) . "\n"; 
return $process_button_string; 
} 
} 
?> 

3. 在checkout_success页面中显示pay now按钮。打开文件"includes/modules/pages/checkout_success/header.php"，在文件的末尾添加下面的代码（如果你已经掌握zen-cart中的通知者/观察者模式，并且又不想破坏zen-cart核心代码的话，也可以创建一个观察类来监听NOTIFY_HEADER_END_CHECKOUT_SUCCESS来实现）。

 
require_once(DIR_WS_CLASSES . 'order.php'); 
require_once(DIR_WS_CLASSES . 'payment.php'); 
$payment_modules = new payment($orders->fields['payment_module_code']); 

打开文件"includes/modules/templates/template_default/templates/tpl_checkout_success_default.php"，并在适当的位置加上如下的代码，这里对订单的状态进行了一个判断，当只有订单的状态在未付款状态，才显示该按钮，

 
<div id="pay_now"> 
<?php 
//&& $orders->fields['orders_status'] == '1' 
if(isset($payment_modules->paynow_action_url) && $payment_modules->paynow_action_url != ''&& $orders->fields['orders_status'] == '1'){ 
echo('<fieldset id="csNotifications">'); 
echo('<legend>'.TEXT_PAYNOW.'</legend>'); 
echo zen_draw_form('checkout_paynow', $payment_modules->paynow_action_url, 'post', 'id="checkout_confirmation" onsubmit="submitonce();"'); 
$selection = $payment_modules->selection(); 
echo('<div class="buttonRow payment_method">'.$selection[0]['module'].'</div>'); 
echo('<div class="buttonRow forward paynow">'); 
if (is_array($payment_modules->modules)) { 
echo $payment_modules->paynow_button($orders_id); 
} 
echo(zen_image_submit(BUTTON_IMAGE_PAYNOW, BUTTON_IMAGE_PAYNOW_ALT, 'name="btn_paynow" id="btn_paynow"')); 
echo('</div>'); 
echo('</form>'); 
echo('</fieldset>'); 
} 
?> 
</div> 

4. 在历史订单中显示pay now按钮。需要显示pay now按钮的页面有三个：account, account_history,account_history_info，这里的实现和checkout_success页面的实现大同小异，只是传给$payment_modules的函数paynow_button的参数不一样而已，这里就不再赘述。
总结：
经过上面的修改，我们的流程如下：
1. 购物车(shopping cart)
2. [货运方式(delivery method)]
3. 支付方式(payment method)
4. 订单确认(confirmation)
5. 订单处理(checkout process)
6. 下单成功(checkout success)
7. [第三方网站支付]
因为从订单确认到订单处理，都是在我们自己的网站完成的，并且进入支付网站之前，订单已经存在了，这样就不会出现掉单的情况了。