Advanced module development featuring Ubercart uc_etranzact contrib module on Drupal 6. DrupalCamp Lagos 2011.

1. Advanced Module
Development (D6)
Case study: UC_Etranzact Ubercart
contrib module
Kayode Odeyemi
Technical Architect, Opevel
DrupalCamp Lagos 2011

2. Where to start from?
There are various ways of starting a Drupal
module;
• Using Features module: Makes your Drupal
module exportable and deployment easier.
• Using Module Builder module: auto-generates a
skeleton or "scaffolding" for a module

3. Drupal Common Hooks
• Hook_menu
• Hook_init
• Hook_help
• Hook_nodeapi
• Hook_theme
• Hook_install
• Hook_uninstall
• Hook_form
• Hook_form_alter
• Hook_form_submit
• Hook_form_validate

4. Very useful Drupal APIs for everyday development
• Module_invoke
• Module_load_include
• Drupal_write_record
• Function_exists
• Call_user_func_array
• Db_table_exists
• Db_query
• Db_result
• Db_object_fetch_array and db_object_fetch_object
• Drupal_set_message or dsm if using devel module
• Db_create_table
• Update_sql
• Views_get_views_result
• Db_add_field
• Db_drop_field
• Drupal_get_schema
• Element_children
• Views_get_default_view

5. Writing Drupal Hooks
There are different ways of writing Drupal hooks.
// Using module_implements inline within a non-hook function and using module_invoke
foreach(module_implements(‘hook_name') as $module) {
module_invoke($module, ‘hook_name', $args);
}
// Explicitly writing the hook as a function with module_implements alone
function mymodule_hook($fees) {
foreach (module_implements(‘hook_name') as $module) {
$function = $module . '_hook_name';
$result = $function($fees);
if (isset($result) && is_array($result)) {
$return = array_merge($return, $result);
}
else if (isset($result)) {
$return[] = $result;
}
}
return $return;
}

6. drupal_http_request: Drupal's simple curl equivalent
// curl
$curl = curl_init(); $apiurl =
variable_get('uc_etranzact_demo_mode', 1) ?
UC_ETRANZACT_SERVICE_DEMO :
UC_ETRANZACT_SERVICE; $apiurl = sprintf('%s?%s',
$apiurl, $query); curl_setopt($curl, CURLOPT_URL,
$apiurl); curl_setopt($curl,
CURLOPT_RETURNTRANSFER, 1); curl_setopt($curl,
CURLOPT_SSL_VERIFYPEER, FALSE); curl_setopt($curl,
CURLOPT_FOLLOWLOCATION, 1); $return =
curl_exec($curl);
// drupal_http_request
$result = drupal_http_request($uri, $header, $method,
http_build_query($data, '', '&'));

7. Test with SimpleTest
• When your project is starting to get robust and clumsy, test with
SimpleTest
• Common SimpleTest APIs are:
– drupalGetNodeByTitle($title)
– drupalCreateNode($settings)
– drupalCreateContentType($settings) -
drupalCreateUser($permissions)
– checkPermissions(array $permissions, $reset = FALSE): Check
to make sure that the array of permissions are valid.
– drupalLogin(stdClass $user): Log in a user with the internal
browser.

8. Test with SimpleTest
– drupalLogout
– assertNotEqual: Check to see if two values are not equal.
– assertEqual: Check to see if two values are equal.
– drupalPost: Execute a POST request on a Drupal page.
– drupalGet: Retrieves a Drupal path or an absolute path.
– assertTrue: Check to see if a value is not false (not an empty
string, 0, NULL, or FALSE)
– assertFalse: Check to see if a value is false (an empty string, 0,
NULL, or FALSE).
– assertNull: Check to see if a value is not NULL.

9. Administer Drupal faster with Drupal
• Drush is Drupal’s CLI language
• Administer modules quickly with Drush
• When working with multi-sites, Drush is your best friend
• Drupal cheat sheet
– Drush status
– Drush dl <modulename>
– Drush cc
– Drush eval “<php code>”
– Drush en <module name>
– Drush dis <module name>
– Drush up
– Drush upc <module name>
– … more on drupal.org

10. Debugging Drupal
• The devel module and theme developer modules are
very handy tools for Debugging Drupal.
• There’s also a firebug Drupal extension for debugging
Drupal
• Useful functions:
– Dsm
– Dpr
– dvm

11. Ubercart Payment Hooks and useful APIs
• Hook_payment_method: define a custom payment method
• Hook_order: define and process the order items
• Hook_checkout_pane: define a custom pane for your order and
style it
• uc_order_status_data: Check the status of an order
• uc_cart_empty(uc_cart_get_id()): Empty a cart
• uc_order_save($order): save an order to the database
• Hook_tapir_table_alter
• Hook_cart_item: alter the items in cart
• Hook_cart_pane: Override the cart pane
• Hook_product_description: modify the descriptions of items in cart
• Uc_cart_get_contents: get cart contents

12. Understanding ubercart cart process
• Add items to cart using uc_cart_add_items.
• Checkout your order and implement
hook_checkout_pane to customize the order
items.
• Review the order in different states namely:
– New: only called if the order is new
– Submit: Process the order such as integrating with a
payment gateway like etranzact.
– Save: Save your order in a database
– Load: called immediately an order is successfully
saved in the db

13. How we build it: uc_etranzact module
• Uc_etranzact module only requires a payment
gateway implementation
• Ubercart Hooks that got the job done:
– Hook_payment_gateway
– Hook_order
– Callback functions to process the order to
integrate with etranzact system

14. Questions
• Website - http://opevel.com
• Twitter : @opevel @drupal @acquia
• Opevel Services
– Drupal custom development
– Drupal site architecture
– Custom Application Development on Google App Engine
http://drupal.org/sandbox/charyorde/1310706
• Datasphir is hiring Drupal developers. – http://datasphir.com