Module base creation

Composer autoloading

Let’s create module folder demovieworderhooks inside modules directory (located in the root of PrestaShop project). Then create composer.json in the root of the module to autoload classes with the namespaces (PrestaShop\Module\DemoViewOrderHooks\) we define from the src folder (https://getcomposer.org/doc/01-basic-usage.md#autoloading). Using composer PSR-4 autoload helps us autoload classes without the need to use require_once __DIR__.'/vendor/autoload.php'; .

Even though using autoload block in composer.json helps us to autoload classes from the specified folder src with the namespace PrestaShop\\Module\\DemoViewOrderHooks\\ we might have some autoloading issues if we use our classes in our module main file demovieworderhooks.php. For example, we might define a constant if one of our class and use it in demovieworderhooks.php when we will get error: the class is not defined. Then a solution can be including require_once __DIR__.'/vendor/autoload.php'; before the main module class demovieworderhooks is defined.
{
    "name": "prestashop/demovieworderhooks",
    "authors": [
        {
            "name": "Name Surname",
            "email": "author@email.com"
        }
    ],
    "autoload": {
      "psr-4": {
        "PrestaShop\\Module\\DemoViewOrderHooks\\": "src/"
      },
      "config": {
        "prepend-autoloader": false
      },
      "type": "prestashop-module"
    }
}

Then run composer install on the terminal/command line inside /modules/demovieworderhooks/ folder. Also run composer dump-autoload to re-generate the vendor/autoload.php file. If files were autoloaded successfully you should see something similar to PrestaShop\\Module\\DemoViewOrderHooks\\' => array($baseDir . '/src') in modules/demovieworderhooks/vendor/composer/autoload_psr4.php generated.

Module installation

Let’s use SOLID principles (https://en.wikipedia.org/wiki/SOLID) to make code more understandable, flexible and maintainable. Create FixturesInstaller class inside /demovieworderhooks/src/Install folder to represent Single responsibility principle (https://en.wikipedia.org/wiki/Single_responsibility_principle) responsible only for module fixtures data inserted to the database.

<?php
/**
 * Copyright since 2007 PrestaShop SA and Contributors
 * PrestaShop is an International Registered Trademark & Property of PrestaShop SA
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Academic Free License 3.0 (AFL-3.0).
 * It is also available through the world-wide-web at this URL: https://opensource.org/licenses/AFL-3.0
 */

declare(strict_types=1);

namespace PrestaShop\Module\DemoViewOrderHooks\Install;

use Db;
use Order;

/**
 * Installs data fixtures for the module.
 */
class FixturesInstaller
{
    /**
     * @var Db
     */
    private $db;

    public function __construct(Db $db)
    {
        $this->db = $db;
    }

    public function install(): void
    {
        $orderIds = Order::getOrdersIdByDate('2000-01-01', '2100-01-01');

        foreach ($orderIds as $orderId) {
            $this->insertSignature($orderId);
        }
    }

    private function insertSignature(int $orderId): void
    {
        $this->db->insert('order_signature', [
            'id_order' => $orderId,
            'filename' => 'john_doe.png',
        ]);
    }
}

Lets create Installer class inside /demovieworderhooks/src/Install folder structure. It is responsible only for module installation (hook registration, database creation, population database data). When it comes to database creation we use PrestaShop DbCore class functions because doctrine is not fully supported for modules installation at 1.7.7.0 release (https://devdocs.prestashop.com/1.7/modules/concepts/doctrine/#creating-the-database).

<?php
/**
 * Copyright since 2007 PrestaShop SA and Contributors
 * PrestaShop is an International Registered Trademark & Property of PrestaShop SA
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Academic Free License 3.0 (AFL-3.0).
 * It is also available through the world-wide-web at this URL: https://opensource.org/licenses/AFL-3.0
 */

declare(strict_types=1);

namespace PrestaShop\Module\DemoViewOrderHooks\Install;

use Db;
use Module;

/**
 * Class responsible for modifications needed during installation/uninstallation of the module.
 */
class Installer
{
    /**
     * @var FixturesInstaller
     */
    private $fixturesInstaller;

    public function __construct(FixturesInstaller $fixturesInstaller)
    {
        $this->fixturesInstaller = $fixturesInstaller;
    }

    /**
     * Module's installation entry point.
     *
     * @param Module $module
     *
     * @return bool
     */
    public function install(Module $module): bool
    {
        if (!$this->registerHooks($module)) {
            return false;
        }

        if (!$this->installDatabase()) {
            return false;
        }

        $this->fixturesInstaller->install();

        return true;
    }

    /**
     * Module's uninstallation entry point.
     *
     * @return bool
     */
    public function uninstall(): bool
    {
        return $this->uninstallDatabase();
    }

    /**
     * Install the database modifications required for this module.
     *
     * @return bool
     */
    private function installDatabase(): bool
    {
        $queries = [
            'CREATE TABLE IF NOT EXISTS `'._DB_PREFIX_.'order_signature` (
              `id_signature` int(11) NOT NULL AUTO_INCREMENT,
              `id_order` int(11) NOT NULL,
              `filename` varchar(64) NOT NULL,
              PRIMARY KEY (`id_signature`),
              UNIQUE KEY (`id_order`)
            ) ENGINE='._MYSQL_ENGINE_.' DEFAULT CHARSET=utf8;',
        ];

        return $this->executeQueries($queries);
    }

    /**
     * Uninstall database modifications.
     *
     * @return bool
     */
    private function uninstallDatabase(): bool
    {
        $queries = [
            'DROP TABLE IF EXISTS `'._DB_PREFIX_.'order_signature`',
        ];

        return $this->executeQueries($queries);
    }

    /**
     * Register hooks for the module.
     *
     * @param Module $module
     *
     * @return bool
     */
    private function registerHooks(Module $module): bool
    {
        // Hooks available in the order view page.
        $hooks = [
            'displayBackOfficeOrderActions',
            'displayAdminOrderTabLink',
            'displayAdminOrderTabContent',
            'displayAdminOrderMain',
            'displayAdminOrderSide',
            'displayAdminOrder',
            'displayAdminOrderTop',
            'actionGetAdminOrderButtons',
        ];

        return (bool) $module->registerHook($hooks);
    }

    /**
     * A helper that executes multiple database queries.
     *
     * @param array $queries
     *
     * @return bool
     */
    private function executeQueries(array $queries): bool
    {
        foreach ($queries as $query) {
            if (!Db::getInstance()->execute($query)) {
                return false;
            }
        }

        return true;
    }
}

Then let’s create InstallerFactory inside /demovieworderhooks/src/Install which will be used to create Installer object. We call it factory because it deals with creating objects without having to specify the exact class of the object that will be created. More about factory design pattern: https://en.wikipedia.org/wiki/Factory_method_pattern

<?php
/**
 * Copyright since 2007 PrestaShop SA and Contributors
 * PrestaShop is an International Registered Trademark & Property of PrestaShop SA
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Academic Free License 3.0 (AFL-3.0).
 * It is also available through the world-wide-web at this URL: https://opensource.org/licenses/AFL-3.0
 */

declare(strict_types=1);

namespace PrestaShop\Module\DemoViewOrderHooks\Install;

use Db;

class InstallerFactory
{
    public static function create(): Installer
    {
        return new Installer(
            new FixturesInstaller(Db::getInstance())
        );
    }
}

Let’s create main module file: demovieworderhooks.php inside the modules/demovieworderhooks folder. And create DemoViewOrderHooks class which extends the Module class:

<?php
/**
 * Copyright since 2007 PrestaShop SA and Contributors
 * PrestaShop is an International Registered Trademark & Property of PrestaShop SA
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Academic Free License 3.0 (AFL-3.0).
 * It is also available through the world-wide-web at this URL: https://opensource.org/licenses/AFL-3.0
 */

declare(strict_types=1);

use PrestaShop\Module\DemoViewOrderHooks\Install\InstallerFactory;

if (!defined('_PS_VERSION_')) {
    exit;
}

require_once __DIR__.'/vendor/autoload.php';

class DemoViewOrderHooks extends Module
{
    public function __construct()
    {
        $this->name = 'demovieworderhooks';
        $this->author = 'PrestaShop';
        $this->version = '1.0.0';
        $this->ps_versions_compliancy = ['min' => '1.7.7.0', 'max' => _PS_VERSION_];

        parent::__construct();

        $this->displayName = $this->l('Demo view order hooks');
        $this->description = $this->l('Demonstration of new hooks in PrestaShop 1.7.7 order view page');
    }

    public function install()
    {
        if (!parent::install()) {
            return false;
        }

        $installer = InstallerFactory::create();

        return $installer->install($this);
    }

    public function uninstall()
    {
        $installer = InstallerFactory::create();

        return $installer->uninstall() && parent::uninstall();
    }

}

Now we can install the module through PrestaShop Back Office Modules\Module Catalog. In the search box type Demo, click Enter and then you should see the module with name Demo view order hooks suggested for Installation. Click Install, you should see the green box at the top right corner telling you about the success!

Let’s go to create Signature card and Additional action buttons, I am getting excited now!