diff --git a/demoextendsymfonyform3/.gitignore b/demoextendsymfonyform3/.gitignore
new file mode 100644
index 00000000..0ed33711
--- /dev/null
+++ b/demoextendsymfonyform3/.gitignore
@@ -0,0 +1,4 @@
+vendor/
+composer.lock
+.idea
+js/node_modules
diff --git a/demoextendsymfonyform3/README.md b/demoextendsymfonyform3/README.md
new file mode 100755
index 00000000..68f40488
--- /dev/null
+++ b/demoextendsymfonyform3/README.md
@@ -0,0 +1,37 @@
+# Demonstration of how to use CQRS in a module
+
+## About
+
+This module adds a new field to Customer: a yes/no field "is allowed to review".
+This new field appears:
+- in the Customers listing as a new column
+- in the Customers Add/Edit form as a new field you can manage
+
+This modules demonstrates
+ - how to add this field, manage its content and its
+properties using modern hooks in Symfony pages
+ - how to use custom [CQRS](https://devdocs.prestashop.com/1.7/development/architecture/domain/cqrs/) Commands and Queries to separate your domain from your application
+ - how to use Translator inside modern Symfony module
+
+*This part is demonstrated as a possibility for your module, this is
+not mandatory to be done this way.
+
+ ### Supported PrestaShop versions
+
+ This module is compatible with and 1.7.6.0 and above versions.
+ 
+ ### Requirements
+ 
+  1. Composer, see [Composer](https://getcomposer.org/) to learn more
+ 
+ ### How to install
+ 
+  1. Download or clone module into `modules` directory of your PrestaShop installation
+  2. Rename the directory to make sure that module directory is named `demoextendsymfonyform3`*
+  3. `cd` into module's directory and run following commands:
+      - `composer install` - to download dependencies into vendor folder
+  4. Install module from Back Office
+ 
+ *Because the name of the directory and the name of the main module file must match.
+ 
+
diff --git a/demoextendsymfonyform3/composer.json b/demoextendsymfonyform3/composer.json
new file mode 100755
index 00000000..72d1e44f
--- /dev/null
+++ b/demoextendsymfonyform3/composer.json
@@ -0,0 +1,11 @@
+{
+  "name": "prestashop/demoextendsymfonyform3",
+  "description": "Help developers to understand how to create module using new hooks and apply best practices when using CQRS",
+  "autoload": {
+    "psr-4": {
+      "DemoCQRSHooksUsage\\": "src/"
+    }
+  },
+  "license": "MIT",
+  "type": "prestashop-module"
+}
diff --git a/demoextendsymfonyform3/config/routes.yml b/demoextendsymfonyform3/config/routes.yml
new file mode 100755
index 00000000..f7ed5e87
--- /dev/null
+++ b/demoextendsymfonyform3/config/routes.yml
@@ -0,0 +1,8 @@
+# @see https://devdocs.prestashop.com/1.7/modules/concepts/controllers/admin-controllers/#how-to-map-an-action-of-your-controller-to-a-uri
+ps_democqrshooksusage_toggle_is_allowed_for_review:
+  path: demo-cqrs-hook-usage/{customerId}/toggle-is-allowed-for-review
+  methods: [POST]
+  defaults:
+    _controller: 'DemoCQRSHooksUsage\Controller\Admin\CustomerReviewController::toggleIsAllowedForReviewAction'
+  requirements:
+    customerId: \d+
diff --git a/demoextendsymfonyform3/config/services.yml b/demoextendsymfonyform3/config/services.yml
new file mode 100755
index 00000000..403e4e95
--- /dev/null
+++ b/demoextendsymfonyform3/config/services.yml
@@ -0,0 +1,33 @@
+services:
+  _defaults:
+    public: true
+#  @see  https://devdocs.prestashop.com/1.7/development/architecture/migration-guide/forms/cqrs-usage-in-forms/ for CQRS pattern usage examples.
+  democqrshooksusage.domain.reviewer.command_handler.toggle_is_allowed_to_review_handler:
+    class: 'DemoCQRSHooksUsage\Domain\Reviewer\CommandHandler\ToggleIsAllowedToReviewHandler'
+    arguments:
+      - '@democqrshooksusage.repository.reviewer'
+    tags:
+      - name: tactician.handler
+        command: 'DemoCQRSHooksUsage\Domain\Reviewer\Command\ToggleIsAllowedToReviewCommand'
+
+  democqrshooksusage.domain.reviewer.query_handler.get_reviewer_settings_for_form_handler:
+    class: 'DemoCQRSHooksUsage\Domain\Reviewer\QueryHandler\GetReviewerSettingsForFormHandler'
+    arguments:
+      - '@democqrshooksusage.repository.reviewer'
+    tags:
+      - name: tactician.handler
+        command: 'DemoCQRSHooksUsage\Domain\Reviewer\Query\GetReviewerSettingsForForm'
+
+  democqrshooksusage.domain.reviewer.command_handler.update_is_allowed_to_review_handler:
+    class: 'DemoCQRSHooksUsage\Domain\Reviewer\CommandHandler\UpdateIsAllowedToReviewHandler'
+    arguments:
+      - '@democqrshooksusage.repository.reviewer'
+    tags:
+      - name: tactician.handler
+        command: 'DemoCQRSHooksUsage\Domain\Reviewer\Command\UpdateIsAllowedToReviewCommand'
+
+  democqrshooksusage.repository.reviewer:
+    class: 'DemoCQRSHooksUsage\Repository\ReviewerRepository'
+    arguments:
+      - '@doctrine.dbal.default_connection'
+      - '%database_prefix%'
diff --git a/demoextendsymfonyform3/demoextendsymfonyform3.php b/demoextendsymfonyform3/demoextendsymfonyform3.php
new file mode 100755
index 00000000..9c3745f7
--- /dev/null
+++ b/demoextendsymfonyform3/demoextendsymfonyform3.php
@@ -0,0 +1,344 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+use DemoCQRSHooksUsage\Domain\Reviewer\Command\UpdateIsAllowedToReviewCommand;
+use DemoCQRSHooksUsage\Domain\Reviewer\Exception\CannotCreateReviewerException;
+use DemoCQRSHooksUsage\Domain\Reviewer\Exception\CannotToggleAllowedToReviewStatusException;
+use DemoCQRSHooksUsage\Domain\Reviewer\Exception\ReviewerException;
+use DemoCQRSHooksUsage\Domain\Reviewer\Query\GetReviewerSettingsForForm;
+use DemoCQRSHooksUsage\Domain\Reviewer\QueryResult\ReviewerSettingsForForm;
+use Doctrine\DBAL\Query\QueryBuilder;
+use PrestaShop\PrestaShop\Core\CommandBus\CommandBusInterface;
+use PrestaShop\PrestaShop\Core\Domain\Customer\Exception\CustomerException;
+use PrestaShop\PrestaShop\Core\Grid\Column\Type\Common\ToggleColumn;
+use PrestaShop\PrestaShop\Core\Grid\Definition\GridDefinitionInterface;
+use PrestaShop\PrestaShop\Core\Grid\Filter\Filter;
+use PrestaShop\PrestaShop\Core\Search\Filters\CustomerFilters;
+use PrestaShopBundle\Form\Admin\Type\SwitchType;
+use PrestaShopBundle\Form\Admin\Type\YesAndNoChoiceType;
+use Symfony\Component\Form\FormBuilderInterface;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Session\Flash\FlashBagInterface;
+
+/**
+ * Class DemoExtendSymfonyForm1 demonstrates the usage of CQRS pattern and hooks.
+ */
+class DemoExtendSymfonyForm3 extends Module
+{
+    public function __construct()
+    {
+        $this->name = 'demoextendsymfonyform3';
+        $this->version = '1.0.0';
+        $this->author = 'Mathieu Ferment';
+        $this->need_instance = 0;
+
+        parent::__construct();
+
+        $this->displayName = $this->getTranslator()->trans(
+            'Demo Symfony Forms #3',
+            [],
+            'Modules.Democqrshooksusage.Admin'
+        );
+
+        $this->description =
+            $this->getTranslator()->trans(
+                'Help developers to understand how to create module using CQRS',
+                [],
+                'Modules.Democqrshooksusage.Admin'
+            );
+
+        $this->ps_versions_compliancy = [
+            'min' => '1.7.6.0',
+            'max' => _PS_VERSION_,
+        ];
+    }
+
+    /**
+     * This function is required in order to make module compatible with new translation system.
+     *
+     * @return bool
+     */
+    public function isUsingNewTranslationSystem()
+    {
+        return true;
+    }
+
+    /**
+     * Install module and register hooks to allow grid modification.
+     *
+     * @see https://devdocs.prestashop.com/1.7/modules/concepts/hooks/use-hooks-on-modern-pages/
+     *
+     * @return bool
+     */
+    public function install()
+    {
+        return parent::install() &&
+            // Register hook to allow Customer grid definition modifications.
+            // Each grid's definition modification hook has it's own name. Hook name is built using
+            // this structure: "action{grid_id}GridDefinitionModifier", in this case "grid_id" is "customer"
+            // this means we will be modifying "Sell > Customers" page grid.
+            // You can check any definition factory service in PrestaShop\PrestaShop\Core\Grid\Definition\Factory
+            // to see available grid ids. Grid id is returned by `getId()` method.
+            $this->registerHook('actionCustomerGridDefinitionModifier') &&
+            // Register hook to allow Customer grid query modifications which allows to add any sql condition.
+            $this->registerHook('actionCustomerGridQueryBuilderModifier') &&
+            // Register hook to allow overriding customer form
+            // this structure: "action{block_prefix}FormBuilderModifier", in this case "block_prefix" is "customer"
+            // {block_prefix} is either retrieved automatically by its type. E.g "ManufacturerType" will be "manufacturer"
+            // or it can be modified in form type by overriding "getBlockPrefix" function
+            $this->registerHook('actionCustomerFormBuilderModifier') &&
+            $this->registerHook('actionAfterCreateCustomerFormHandler') &&
+            $this->registerHook('actionAfterUpdateCustomerFormHandler') &&
+            $this->installTables()
+            ;
+    }
+
+    public function uninstall()
+    {
+        return parent::uninstall() && $this->uninstallTables();
+    }
+
+    /**
+     * Hook allows to modify Customers grid definition.
+     * This hook is a right place to add/remove columns or actions (bulk, grid).
+     *
+     * @param array $params
+     */
+    public function hookActionCustomerGridDefinitionModifier(array $params)
+    {
+        /** @var GridDefinitionInterface $definition */
+        $definition = $params['definition'];
+
+        $translator = $this->getTranslator();
+
+        $definition
+            ->getColumns()
+            ->addAfter(
+                'optin',
+                (new ToggleColumn('is_allowed_for_review'))
+                    ->setName($translator->trans('Allowed for review', [], 'Modules.Democqrshooksusage.Admin'))
+                    ->setOptions([
+                        'field' => 'is_allowed_for_review',
+                        'primary_field' => 'id_customer',
+                        'route' => 'ps_democqrshooksusage_toggle_is_allowed_for_review',
+                        'route_param_name' => 'customerId',
+                    ])
+            )
+        ;
+
+        $definition->getFilters()->add(
+            (new Filter('is_allowed_for_review', YesAndNoChoiceType::class))
+                ->setAssociatedColumn('is_allowed_for_review')
+        );
+    }
+
+    /**
+     * Hook allows to modify Customers query builder and add custom sql statements.
+     *
+     * @param array $params
+     */
+    public function hookActionCustomerGridQueryBuilderModifier(array $params)
+    {
+        /** @var QueryBuilder $searchQueryBuilder */
+        $searchQueryBuilder = $params['search_query_builder'];
+
+        /** @var CustomerFilters $searchCriteria */
+        $searchCriteria = $params['search_criteria'];
+
+        $searchQueryBuilder->addSelect(
+            'IF(dcur.`is_allowed_for_review` IS NULL,0,dcur.`is_allowed_for_review`) AS `is_allowed_for_review`'
+        );
+
+        $searchQueryBuilder->leftJoin(
+            'c',
+            '`' . pSQL(_DB_PREFIX_) . 'democqrshooksusage_reviewer`',
+            'dcur',
+            'dcur.`id_customer` = c.`id_customer`'
+        );
+
+        if ('is_allowed_for_review' === $searchCriteria->getOrderBy()) {
+            $searchQueryBuilder->orderBy('dcur.`is_allowed_for_review`', $searchCriteria->getOrderWay());
+        }
+
+        foreach ($searchCriteria->getFilters() as $filterName => $filterValue) {
+            if ('is_allowed_for_review' === $filterName) {
+                $searchQueryBuilder->andWhere('dcur.`is_allowed_for_review` = :is_allowed_for_review');
+                $searchQueryBuilder->setParameter('is_allowed_for_review', $filterValue);
+
+                if (!$filterValue) {
+                    $searchQueryBuilder->orWhere('dcur.`is_allowed_for_review` IS NULL');
+                }
+            }
+        }
+    }
+
+    /**
+     * Hook allows to modify Customers form and add additional form fields as well as modify or add new data to the forms.
+     *
+     * @param array $params
+     */
+    public function hookActionCustomerFormBuilderModifier(array $params)
+    {
+        /** @var FormBuilderInterface $formBuilder */
+        $formBuilder = $params['form_builder'];
+        $formBuilder->add('is_allowed_for_review', SwitchType::class, [
+            'label' => $this->getTranslator()->trans('Allow reviews', [], 'Modules.Democqrshooksusage.Admin'),
+            'required' => false,
+        ]);
+
+        /**
+         * @var CommandBusInterface
+         */
+        $queryBus = $this->get('prestashop.core.query_bus');
+
+        /**
+         * This part demonstrates the usage of CQRS pattern query to perform read operation from Reviewer entity.
+         *
+         * @see https://devdocs.prestashop.com/1.7/development/architecture/cqrs/ for more detailed information.
+         *
+         * As this is our recommended approach of reading the data but we not force to use this pattern in modules -
+         * you can use directly an entity here or wrap it in custom service class.
+         *
+         * @var ReviewerSettingsForForm
+         */
+        $reviewerSettings = $queryBus->handle(new GetReviewerSettingsForForm($params['id']));
+
+        $params['data']['is_allowed_for_review'] = $reviewerSettings->isAllowedForReview();
+
+        $formBuilder->setData($params['data']);
+    }
+
+    /**
+     * Hook allows to modify Customers form and add additional form fields as well as modify or add new data to the forms.
+     *
+     * @param array $params
+     *
+     * @throws CustomerException
+     */
+    public function hookActionAfterUpdateCustomerFormHandler(array $params)
+    {
+        $this->updateCustomerReviewStatus($params);
+    }
+
+    /**
+     * Hook allows to modify Customers form and add additional form fields as well as modify or add new data to the forms.
+     *
+     * @param array $params
+     *
+     * @throws CustomerException
+     */
+    public function hookActionAfterCreateCustomerFormHandler(array $params)
+    {
+        $this->updateCustomerReviewStatus($params);
+    }
+
+    /**
+     * @param array $params
+     *
+     * @throws \PrestaShop\PrestaShop\Core\Module\Exception\ModuleErrorException
+     */
+    private function updateCustomerReviewStatus(array $params)
+    {
+        $customerId = $params['id'];
+        /** @var array $customerFormData */
+        $customerFormData = $params['form_data'];
+        $isAllowedForReview = (bool) $customerFormData['is_allowed_for_review'];
+
+        /** @var CommandBusInterface $commandBus */
+        $commandBus = $this->get('prestashop.core.command_bus');
+
+        try {
+            /*
+             * This part demonstrates the usage of CQRS pattern command to perform write operation for Reviewer entity.
+             * @see https://devdocs.prestashop.com/1.7/development/architecture/cqrs/ for more detailed information.
+             *
+             * As this is our recommended approach of writing the data but we not force to use this pattern in modules -
+             * you can use directly an entity here or wrap it in custom service class.
+             */
+            $commandBus->handle(new UpdateIsAllowedToReviewCommand(
+                $customerId,
+                $isAllowedForReview
+            ));
+        } catch (ReviewerException $exception) {
+            $this->handleException($exception);
+        }
+    }
+
+    /**
+     * Installs sample tables required for demonstration.
+     *
+     * @return bool
+     */
+    private function installTables()
+    {
+        $sql = '
+            CREATE TABLE IF NOT EXISTS `' . pSQL(_DB_PREFIX_) . 'democqrshooksusage_reviewer` (
+                `id_reviewer` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
+                `id_customer` INT(10) UNSIGNED NOT NULL,
+                `is_allowed_for_review` TINYINT(1) NOT NULL,
+                PRIMARY KEY (`id_reviewer`)
+            ) ENGINE=' . pSQL(_MYSQL_ENGINE_) . ' COLLATE=utf8_unicode_ci;
+        ';
+
+        return Db::getInstance()->execute($sql);
+    }
+
+    /**
+     * Uninstalls sample tables required for demonstration.
+     *
+     * @return bool
+     */
+    private function uninstallTables()
+    {
+        $sql = 'DROP TABLE IF EXISTS `' . pSQL(_DB_PREFIX_) . 'democqrshooksusage_reviewer`';
+
+        return Db::getInstance()->execute($sql);
+    }
+
+    /**
+     * Handles exceptions and displays message in more user friendly form.
+     *
+     * @param ReviewerException $exception
+     *
+     * @throws \PrestaShop\PrestaShop\Core\Module\Exception\ModuleErrorException
+     */
+    private function handleException(ReviewerException $exception)
+    {
+        $exceptionDictionary = [
+            CannotCreateReviewerException::class => $this->getTranslator()->trans(
+                'Failed to create a record for customer',
+                [],
+                'Modules.Democqrshooksusage.Admin'
+            ),
+            CannotToggleAllowedToReviewStatusException::class => $this->getTranslator()->trans(
+                'Failed to toggle is allowed to review status',
+                [],
+                'Modules.Democqrshooksusage.Admin'
+            ),
+        ];
+
+        $exceptionType = get_class($exception);
+
+        if (isset($exceptionDictionary[$exceptionType])) {
+            $message = $exceptionDictionary[$exceptionType];
+        } else {
+            $message = $this->getTranslator()->trans(
+                'An unexpected error occurred. [%type% code %code%]',
+                [
+                    '%type%' => $exceptionType,
+                    '%code%' => $exception->getCode(),
+                ],
+                'Admin.Notifications.Error'
+            );
+        }
+
+        throw new \PrestaShop\PrestaShop\Core\Module\Exception\ModuleErrorException($message);
+    }
+}
diff --git a/demoextendsymfonyform3/src/Controller/Admin/CustomerReviewController.php b/demoextendsymfonyform3/src/Controller/Admin/CustomerReviewController.php
new file mode 100755
index 00000000..f5732737
--- /dev/null
+++ b/demoextendsymfonyform3/src/Controller/Admin/CustomerReviewController.php
@@ -0,0 +1,80 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Controller\Admin;
+
+use DemoCQRSHooksUsage\Domain\Reviewer\Command\ToggleIsAllowedToReviewCommand;
+use DemoCQRSHooksUsage\Domain\Reviewer\Exception\CannotCreateReviewerException;
+use DemoCQRSHooksUsage\Domain\Reviewer\Exception\CannotToggleAllowedToReviewStatusException;
+use DemoCQRSHooksUsage\Domain\Reviewer\Exception\ReviewerException;
+use PrestaShop\PrestaShop\Core\Domain\Customer\Exception\CustomerException;
+use PrestaShopBundle\Controller\Admin\FrameworkBundleAdminController;
+use Symfony\Component\HttpFoundation\RedirectResponse;
+
+/**
+ * This controller holds all custom actions which are added by extending "Sell > Customers" page.
+ *
+ * @see https://devdocs.prestashop.com/1.7/modules/concepts/controllers/admin-controllers/ for more details.
+ */
+class CustomerReviewController extends FrameworkBundleAdminController
+{
+    /**
+     * Catches the toggle action of customer review.
+     *
+     * @param int $customerId
+     *
+     * @return RedirectResponse
+     */
+    public function toggleIsAllowedForReviewAction($customerId)
+    {
+        try {
+            /*
+             * This part demonstrates the usage of CQRS pattern command to perform write operation for Reviewer entity.
+             * @see https://devdocs.prestashop.com/1.7/development/architecture/cqrs/ for more detailed information.
+             *
+             * As this is our recommended approach of writing the data but we not force to use this pattern in modules -
+             * you can use directly an entity here or wrap it in custom service class.
+             */
+            $this->getCommandBus()->handle(new ToggleIsAllowedToReviewCommand((int) $customerId));
+
+            $this->addFlash('success', $this->trans('Successful update.', 'Admin.Notifications.Success'));
+        } catch (ReviewerException $e) {
+            $this->addFlash('error', $this->getErrorMessageForException($e, $this->getErrorMessageMapping()));
+        }
+
+        return $this->redirectToRoute('admin_customers_index');
+    }
+
+    /**
+     * Gets error message mappings which are later used to display friendly user error message instead of the
+     * exception message.
+     *
+     * @see https://devdocs.prestashop.com/1.7/development/architecture/domain-exceptions/ for more detailed explanation
+     *
+     * @return array
+     */
+    private function getErrorMessageMapping()
+    {
+        return [
+            CustomerException::class => $this->trans(
+                'Something bad happened when trying to get customer id',
+                'Modules.Democqrshooksusage.Customerreviewcontroller'
+            ),
+            CannotCreateReviewerException::class => $this->trans(
+                'Failed to create reviewer',
+                'Modules.Democqrshooksusage.Customerreviewcontroller'
+            ),
+            CannotToggleAllowedToReviewStatusException::class => $this->trans(
+                'An error occurred while updating the status.',
+                'Modules.Democqrshooksusage.Customerreviewcontroller'
+            ),
+        ];
+    }
+}
diff --git a/demoextendsymfonyform3/src/Domain/Reviewer/Command/ToggleIsAllowedToReviewCommand.php b/demoextendsymfonyform3/src/Domain/Reviewer/Command/ToggleIsAllowedToReviewCommand.php
new file mode 100755
index 00000000..f4547fc8
--- /dev/null
+++ b/demoextendsymfonyform3/src/Domain/Reviewer/Command/ToggleIsAllowedToReviewCommand.php
@@ -0,0 +1,45 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Domain\Reviewer\Command;
+
+use PrestaShop\PrestaShop\Core\Domain\Customer\Exception\CustomerException;
+use PrestaShop\PrestaShop\Core\Domain\Customer\ValueObject\CustomerId;
+
+/**
+ * Used for toggling the customer if is allowed to make a review.
+ *
+ * @see \DemoCQRSHooksUsage\Domain\Reviewer\CommandHandler\ToggleIsAllowedToReviewHandler how the data is handled.
+ */
+class ToggleIsAllowedToReviewCommand
+{
+    /**
+     * @var CustomerId
+     */
+    private $customerId;
+
+    /**
+     * @param int $customerId
+     *
+     * @throws CustomerException
+     */
+    public function __construct($customerId)
+    {
+        $this->customerId = new CustomerId($customerId);
+    }
+
+    /**
+     * @return CustomerId
+     */
+    public function getCustomerId()
+    {
+        return $this->customerId;
+    }
+}
diff --git a/demoextendsymfonyform3/src/Domain/Reviewer/Command/UpdateIsAllowedToReviewCommand.php b/demoextendsymfonyform3/src/Domain/Reviewer/Command/UpdateIsAllowedToReviewCommand.php
new file mode 100644
index 00000000..b81704f9
--- /dev/null
+++ b/demoextendsymfonyform3/src/Domain/Reviewer/Command/UpdateIsAllowedToReviewCommand.php
@@ -0,0 +1,60 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Domain\Reviewer\Command;
+
+use PrestaShop\PrestaShop\Core\Domain\Customer\Exception\CustomerException;
+use PrestaShop\PrestaShop\Core\Domain\Customer\ValueObject\CustomerId;
+
+/**
+ * used to update customers review status.
+ *
+ * @see \DemoCQRSHooksUsage\Domain\Reviewer\CommandHandler\UpdateIsAllowedToReviewHandler how the data is handled.
+ */
+class UpdateIsAllowedToReviewCommand
+{
+    /**
+     * @var CustomerId
+     */
+    private $customerId;
+
+    /**
+     * @var bool
+     */
+    private $isAllowedToReview;
+
+    /**
+     * @param int $customerId
+     * @param bool $isAllowedToReview
+     *
+     * @throws CustomerException
+     */
+    public function __construct($customerId, $isAllowedToReview)
+    {
+        $this->customerId = new CustomerId($customerId);
+        $this->isAllowedToReview = $isAllowedToReview;
+    }
+
+    /**
+     * @return CustomerId
+     */
+    public function getCustomerId()
+    {
+        return $this->customerId;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isAllowedToReview()
+    {
+        return $this->isAllowedToReview;
+    }
+}
diff --git a/demoextendsymfonyform3/src/Domain/Reviewer/CommandHandler/AbstractReviewerHandler.php b/demoextendsymfonyform3/src/Domain/Reviewer/CommandHandler/AbstractReviewerHandler.php
new file mode 100644
index 00000000..a9773835
--- /dev/null
+++ b/demoextendsymfonyform3/src/Domain/Reviewer/CommandHandler/AbstractReviewerHandler.php
@@ -0,0 +1,61 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Domain\Reviewer\CommandHandler;
+
+use DemoCQRSHooksUsage\Domain\Reviewer\Exception\CannotCreateReviewerException;
+use DemoCQRSHooksUsage\Entity\Reviewer;
+
+/**
+ * Holds the abstraction for common actions for reviewer commands.
+ */
+class AbstractReviewerHandler
+{
+    /**
+     * Creates a reviewer.
+     *
+     * @param $customerId
+     *
+     * @return Reviewer
+     *
+     * @throws CannotCreateReviewerException
+     */
+    protected function createReviewer($customerId)
+    {
+        try {
+            $reviewer = new Reviewer();
+            $reviewer->id_customer = $customerId;
+            $reviewer->is_allowed_for_review = 0;
+
+            if (false === $reviewer->save()) {
+                throw new CannotCreateReviewerException(
+                    sprintf(
+                        'An error occurred when creating reviewer with customer id "%s"',
+                        $customerId
+                    )
+                );
+            }
+        } catch (PrestaShopException $exception) {
+            /*
+             * @see https://devdocs.prestashop.com/1.7/development/architecture/domain-exceptions/
+             */
+            throw new CannotCreateReviewerException(
+                sprintf(
+                    'An unexpected error occurred when creating reviewer with customer id "%s"',
+                    $customerId
+                ),
+                0,
+                $exception
+            );
+        }
+
+        return $reviewer;
+    }
+}
diff --git a/demoextendsymfonyform3/src/Domain/Reviewer/CommandHandler/ToggleIsAllowedToReviewHandler.php b/demoextendsymfonyform3/src/Domain/Reviewer/CommandHandler/ToggleIsAllowedToReviewHandler.php
new file mode 100755
index 00000000..6484f74b
--- /dev/null
+++ b/demoextendsymfonyform3/src/Domain/Reviewer/CommandHandler/ToggleIsAllowedToReviewHandler.php
@@ -0,0 +1,71 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Domain\Reviewer\CommandHandler;
+
+use DemoCQRSHooksUsage\Domain\Reviewer\Command\ToggleIsAllowedToReviewCommand;
+use DemoCQRSHooksUsage\Domain\Reviewer\Exception\CannotCreateReviewerException;
+use DemoCQRSHooksUsage\Domain\Reviewer\Exception\CannotToggleAllowedToReviewStatusException;
+use DemoCQRSHooksUsage\Entity\Reviewer;
+use DemoCQRSHooksUsage\Repository\ReviewerRepository;
+use PrestaShopException;
+
+/**
+ * Used for toggling the customer if is allowed to make a review.
+ */
+class ToggleIsAllowedToReviewHandler extends AbstractReviewerHandler
+{
+    /**
+     * @var ReviewerRepository
+     */
+    private $reviewerRepository;
+
+    /**
+     * @param ReviewerRepository $reviewerRepository
+     */
+    public function __construct(ReviewerRepository $reviewerRepository)
+    {
+        $this->reviewerRepository = $reviewerRepository;
+    }
+
+    /**
+     * @param ToggleIsAllowedToReviewCommand $command
+     *
+     * @throws CannotCreateReviewerException
+     * @throws CannotToggleAllowedToReviewStatusException
+     */
+    public function handle(ToggleIsAllowedToReviewCommand $command)
+    {
+        $reviewerId = $this->reviewerRepository->findIdByCustomer($command->getCustomerId()->getValue());
+
+        $reviewer = new Reviewer($reviewerId);
+
+        if (0 >= $reviewer->id) {
+            $reviewer = $this->createReviewer($command->getCustomerId()->getValue());
+        }
+
+        $reviewer->is_allowed_for_review = (bool) !$reviewer->is_allowed_for_review;
+
+        try {
+            if (false === $reviewer->update()) {
+                throw new CannotToggleAllowedToReviewStatusException(
+                    sprintf('Failed to change status for reviewer with id "%s"', $reviewer->id)
+                );
+            }
+        } catch (PrestaShopException $exception) {
+            /*
+             * @see https://devdocs.prestashop.com/1.7/development/architecture/domain-exceptions/
+             */
+            throw new CannotToggleAllowedToReviewStatusException(
+                'An unexpected error occurred when updating reviewer status'
+            );
+        }
+    }
+}
diff --git a/demoextendsymfonyform3/src/Domain/Reviewer/CommandHandler/UpdateIsAllowedToReviewHandler.php b/demoextendsymfonyform3/src/Domain/Reviewer/CommandHandler/UpdateIsAllowedToReviewHandler.php
new file mode 100644
index 00000000..a99c8865
--- /dev/null
+++ b/demoextendsymfonyform3/src/Domain/Reviewer/CommandHandler/UpdateIsAllowedToReviewHandler.php
@@ -0,0 +1,64 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Domain\Reviewer\CommandHandler;
+
+use DemoCQRSHooksUsage\Domain\Reviewer\Command\UpdateIsAllowedToReviewCommand;
+use DemoCQRSHooksUsage\Domain\Reviewer\Exception\CannotToggleAllowedToReviewStatusException;
+use DemoCQRSHooksUsage\Entity\Reviewer;
+use DemoCQRSHooksUsage\Repository\ReviewerRepository;
+use PrestaShopException;
+
+/**
+ * used to update customers review status.
+ */
+class UpdateIsAllowedToReviewHandler extends AbstractReviewerHandler
+{
+    /**
+     * @var ReviewerRepository
+     */
+    private $reviewerRepository;
+
+    /**
+     * @param ReviewerRepository $reviewerRepository
+     */
+    public function __construct(ReviewerRepository $reviewerRepository)
+    {
+        $this->reviewerRepository = $reviewerRepository;
+    }
+
+    public function handle(UpdateIsAllowedToReviewCommand $command)
+    {
+        $reviewerId = $this->reviewerRepository->findIdByCustomer($command->getCustomerId()->getValue());
+
+        $reviewer = new Reviewer($reviewerId);
+
+        if (0 >= $reviewer->id) {
+            $reviewer = $this->createReviewer($command->getCustomerId()->getValue());
+        }
+
+        $reviewer->is_allowed_for_review = $command->isAllowedToReview();
+
+        try {
+            if (false === $reviewer->update()) {
+                throw new CannotToggleAllowedToReviewStatusException(
+                    sprintf('Failed to change status for reviewer with id "%s"', $reviewer->id)
+                );
+            }
+        } catch (PrestaShopException $exception) {
+            /*
+             * @see https://devdocs.prestashop.com/1.7/development/architecture/domain-exceptions/
+             */
+            throw new CannotToggleAllowedToReviewStatusException(
+                'An unexpected error occurred when updating reviewer status'
+            );
+        }
+    }
+}
diff --git a/demoextendsymfonyform3/src/Domain/Reviewer/Exception/CannotCreateReviewerException.php b/demoextendsymfonyform3/src/Domain/Reviewer/Exception/CannotCreateReviewerException.php
new file mode 100644
index 00000000..b8dddf4f
--- /dev/null
+++ b/demoextendsymfonyform3/src/Domain/Reviewer/Exception/CannotCreateReviewerException.php
@@ -0,0 +1,15 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Domain\Reviewer\Exception;
+
+class CannotCreateReviewerException extends ReviewerException
+{
+}
diff --git a/demoextendsymfonyform3/src/Domain/Reviewer/Exception/CannotToggleAllowedToReviewStatusException.php b/demoextendsymfonyform3/src/Domain/Reviewer/Exception/CannotToggleAllowedToReviewStatusException.php
new file mode 100644
index 00000000..de0bdc82
--- /dev/null
+++ b/demoextendsymfonyform3/src/Domain/Reviewer/Exception/CannotToggleAllowedToReviewStatusException.php
@@ -0,0 +1,15 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Domain\Reviewer\Exception;
+
+class CannotToggleAllowedToReviewStatusException extends ReviewerException
+{
+}
diff --git a/demoextendsymfonyform3/src/Domain/Reviewer/Exception/ReviewerException.php b/demoextendsymfonyform3/src/Domain/Reviewer/Exception/ReviewerException.php
new file mode 100644
index 00000000..8b798f82
--- /dev/null
+++ b/demoextendsymfonyform3/src/Domain/Reviewer/Exception/ReviewerException.php
@@ -0,0 +1,15 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Domain\Reviewer\Exception;
+
+class ReviewerException extends \Exception
+{
+}
diff --git a/demoextendsymfonyform3/src/Domain/Reviewer/Query/GetReviewerSettingsForForm.php b/demoextendsymfonyform3/src/Domain/Reviewer/Query/GetReviewerSettingsForForm.php
new file mode 100644
index 00000000..a36826bf
--- /dev/null
+++ b/demoextendsymfonyform3/src/Domain/Reviewer/Query/GetReviewerSettingsForForm.php
@@ -0,0 +1,42 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Domain\Reviewer\Query;
+
+use PrestaShop\PrestaShop\Core\Domain\Customer\ValueObject\CustomerId;
+
+/**
+ * Gets reviewer settings data ready for form display.
+ *
+ * @see \DemoCQRSHooksUsage\Domain\Reviewer\QueryHandler\GetReviewerSettingsForFormHandler how the data is retrieved.
+ */
+class GetReviewerSettingsForForm
+{
+    /**
+     * @var CustomerId|null
+     */
+    private $customerId;
+
+    /**
+     * @param int|null $customerId
+     */
+    public function __construct($customerId)
+    {
+        $this->customerId = null !== $customerId ? new CustomerId((int) $customerId) : null;
+    }
+
+    /**
+     * @return CustomerId|null
+     */
+    public function getCustomerId()
+    {
+        return $this->customerId;
+    }
+}
diff --git a/demoextendsymfonyform3/src/Domain/Reviewer/QueryHandler/GetReviewerSettingsForFormHandler.php b/demoextendsymfonyform3/src/Domain/Reviewer/QueryHandler/GetReviewerSettingsForFormHandler.php
new file mode 100644
index 00000000..28496f6e
--- /dev/null
+++ b/demoextendsymfonyform3/src/Domain/Reviewer/QueryHandler/GetReviewerSettingsForFormHandler.php
@@ -0,0 +1,45 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Domain\Reviewer\QueryHandler;
+
+use DemoCQRSHooksUsage\Domain\Reviewer\Query\GetReviewerSettingsForForm;
+use DemoCQRSHooksUsage\Domain\Reviewer\QueryResult\ReviewerSettingsForForm;
+use DemoCQRSHooksUsage\Repository\ReviewerRepository;
+
+/**
+ * Gets reviewer settings data ready for form display.
+ */
+class GetReviewerSettingsForFormHandler
+{
+    /**
+     * @var ReviewerRepository
+     */
+    private $reviewerRepository;
+
+    /**
+     * @param ReviewerRepository $reviewerRepository
+     */
+    public function __construct(ReviewerRepository $reviewerRepository)
+    {
+        $this->reviewerRepository = $reviewerRepository;
+    }
+
+    public function handle(GetReviewerSettingsForForm $query)
+    {
+        if (null === $query->getCustomerId()) {
+            return new ReviewerSettingsForForm(false);
+        }
+
+        return new ReviewerSettingsForForm(
+            $this->reviewerRepository->getIsAllowedToReviewStatus($query->getCustomerId()->getValue())
+        );
+    }
+}
diff --git a/demoextendsymfonyform3/src/Domain/Reviewer/QueryResult/ReviewerSettingsForForm.php b/demoextendsymfonyform3/src/Domain/Reviewer/QueryResult/ReviewerSettingsForForm.php
new file mode 100644
index 00000000..4c1dcc6b
--- /dev/null
+++ b/demoextendsymfonyform3/src/Domain/Reviewer/QueryResult/ReviewerSettingsForForm.php
@@ -0,0 +1,38 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Domain\Reviewer\QueryResult;
+
+/**
+ * Holds data used in modified customers form.
+ */
+class ReviewerSettingsForForm
+{
+    /**
+     * @var bool
+     */
+    private $isAllowedForReview;
+
+    /**
+     * @param bool $isAllowedForReview
+     */
+    public function __construct($isAllowedForReview)
+    {
+        $this->isAllowedForReview = $isAllowedForReview;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isAllowedForReview()
+    {
+        return $this->isAllowedForReview;
+    }
+}
diff --git a/demoextendsymfonyform3/src/Entity/Reviewer.php b/demoextendsymfonyform3/src/Entity/Reviewer.php
new file mode 100755
index 00000000..b33ba505
--- /dev/null
+++ b/demoextendsymfonyform3/src/Entity/Reviewer.php
@@ -0,0 +1,38 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Entity;
+
+use PrestaShop\PrestaShop\Adapter\Entity\ObjectModel;
+
+/**
+ * This entity database state is managed by PrestaShop ObjectModel
+ */
+class Reviewer extends ObjectModel
+{
+    /**
+     * @var int
+     */
+    public $id_customer;
+
+    /**
+     * @var int
+     */
+    public $is_allowed_for_review;
+
+    public static $definition = [
+        'table' => 'democqrshooksusage_reviewer',
+        'primary' => 'id_reviewer',
+        'fields' => [
+            'id_customer' => ['type' => self::TYPE_INT, 'validate' => 'isUnsignedInt'],
+            'is_allowed_for_review' => ['type' => self::TYPE_BOOL, 'validate' => 'isBool'],
+        ],
+    ];
+}
diff --git a/demoextendsymfonyform3/src/Repository/ReviewerRepository.php b/demoextendsymfonyform3/src/Repository/ReviewerRepository.php
new file mode 100644
index 00000000..bc91e20f
--- /dev/null
+++ b/demoextendsymfonyform3/src/Repository/ReviewerRepository.php
@@ -0,0 +1,81 @@
+<?php
+/**
+ * 2007-2020 PrestaShop
+ *
+ * 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
+ */
+
+namespace DemoCQRSHooksUsage\Repository;
+
+use Doctrine\DBAL\Connection;
+use PDO;
+
+class ReviewerRepository
+{
+    /**
+     * @var Connection
+     */
+    private $connection;
+
+    /**
+     * @var string
+     */
+    private $dbPrefix;
+
+    /**
+     * @param Connection $connection
+     * @param string $dbPrefix
+     */
+    public function __construct(Connection $connection, $dbPrefix)
+    {
+        $this->connection = $connection;
+        $this->dbPrefix = $dbPrefix;
+    }
+
+    /**
+     * Finds customer id if such exists.
+     *
+     * @param int $customerId
+     *
+     * @return int
+     */
+    public function findIdByCustomer($customerId)
+    {
+        $queryBuilder = $this->connection->createQueryBuilder();
+
+        $queryBuilder
+            ->select('`id_reviewer`')
+            ->from($this->dbPrefix . 'democqrshooksusage_reviewer')
+            ->where('`id_customer` = :customer_id')
+        ;
+
+        $queryBuilder->setParameter('customer_id', $customerId);
+
+        return (int) $queryBuilder->execute()->fetch(PDO::FETCH_COLUMN);
+    }
+
+    /**
+     * Gets allowed to review status by customer.
+     *
+     * @param int $customerId
+     *
+     * @return bool
+     */
+    public function getIsAllowedToReviewStatus($customerId)
+    {
+        $queryBuilder = $this->connection->createQueryBuilder();
+
+        $queryBuilder
+            ->select('`is_allowed_for_review`')
+            ->from($this->dbPrefix . 'democqrshooksusage_reviewer')
+            ->where('`id_customer` = :customer_id')
+        ;
+
+        $queryBuilder->setParameter('customer_id', $customerId);
+
+        return (bool) $queryBuilder->execute()->fetch(PDO::FETCH_COLUMN);
+    }
+}