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To use CQRS you need to:
CommandBus or QueryBus instance using your class constructor.Command or Query.CommandBus or QueryBus.In this example, we will be working with edition in a Contact CRUD Form.
To get started, let’s inject the CommandBus into our Form Data Handler.
#src/PrestaShopBundle/Resources/config/services/core/form/form_data_handler.yml
prestashop.core.form.identifiable_object.data_handler.contact_form_data_handler:
class: 'PrestaShop\PrestaShop\Core\Form\IdentifiableObject\DataHandler\ContactFormDataHandler'
arguments:
- '@prestashop.core.command_bus'
and in ContactFormDataHandler:
<?php
namespace PrestaShop\PrestaShop\Core\Form\IdentifiableObject\DataHandler;
use PrestaShop\PrestaShop\Core\CommandBus\CommandBusInterface;
final class ContactFormDataHandler implements FormDataHandlerInterface
{
/**
* @var CommandBusInterface
*/
private $commandBus;
/**
* @param CommandBusInterface $commandBus
*/
public function __construct(CommandBusInterface $commandBus)
{
$this->commandBus = $commandBus;
}
}
Right now the first step is completed – the Command Bus is injected in the Form Data Handler. Let’s use it!
Instead of modifying the entity object directly in the Form Data Handler’s update() method, we can delegate that task to a Command. All we have to do is create an instance of that command using the form’s $data and then dispatch it using the CommandBus.
<?php
namespace PrestaShop\PrestaShop\Core\Form\IdentifiableObject\DataHandler;
use PrestaShop\PrestaShop\Core\CommandBus\CommandBusInterface;
use PrestaShop\PrestaShop\Core\Domain\Contact\Command\EditContactCommand;
use PrestaShop\PrestaShop\Core\Domain\Contact\Exception\ContactException;
use PrestaShop\PrestaShop\Core\Domain\Contact\ValueObject\ContactId;
final class ContactFormDataHandler implements FormDataHandlerInterface
{
/**
* @var CommandBusInterface
*/
private $commandBus;
/**
* @param CommandBusInterface $commandBus
*/
public function __construct(CommandBusInterface $commandBus)
{
$this->commandBus = $commandBus;
}
/**
* {@inheritdoc}
*
* @throws ContactException
*/
public function update($id, array $data)
{
$editContactCommand = (new EditContactCommand((int) $id))
->setLocalisedTitles($data['title'])
->setEmail($data['email'])
->setIsMessagesSavingEnabled($data['is_messages_saving_enabled'])
->setLocalisedDescription($data['description'])
->setShopAssociation(is_array($data['shop_association']) ? $data['shop_association'] : [])
;
$this->commandBus->handle($editContactCommand);
}
}
In the update() method, EditContactCommand is used to encapsulate the actual action of saving the form. After that, the Command Bus handles the given command (persisting the information).
As a general rule, Commands Handlers return nothing. However, when creating a new object, the created object ID is usually determined by the database engine. How do we handle that?
In this specific case, we allow Command Handlers to return the id of the newly created object after it’s inserted into the database:
<?php
public function create(array $data)
{
$addContactCommand = new AddContactCommand(
$data['title'],
$data['is_messages_saving_enabled']
);
$contactId = $this->commandBus->handle($addContactCommand);
return $contactId->getValue();
}
In this example, the Command Handler for AddContactCommand returns a ContactId value object that contains the contact ID.
In this example, we will be working with edition in a Contact CRUD Form.
First, let’s inject QueryBus instance into the Form Data Provider.
#src/PrestaShopBundle/Resources/config/services/core/form/form_data_provider.yml
prestashop.core.form.identifiable_object.data_provider.contact_form_data_provider:
class: 'PrestaShop\PrestaShop\Core\Form\IdentifiableObject\DataProvider\ContactFormDataProvider'
arguments:
- '@prestashop.core.query_bus'
and in ContactFormDataProvider:
<?php
namespace PrestaShop\PrestaShop\Core\Form\IdentifiableObject\DataProvider;
use PrestaShop\PrestaShop\Core\CommandBus\CommandBusInterface;
final class ContactFormDataProvider implements FormDataProviderInterface
{
/**
* @var CommandBusInterface
*/
private $queryBus;
/**
* @param CommandBusInterface $queryBus
*/
public function __construct(CommandBusInterface $queryBus)
{
$this->queryBus = $queryBus;
}
}
The first step is completed – the Query Bus is injected in the Form Data Provider. Let’s use it!
Instead of retrieving the data using an SQL query or retrieving the entity data using ObjectModel directly in the Form Data Provider’s getData() method, we can delegate that task to a Query. All that we have to do is create an instance of the Query using provided $id and dispatch it using the QueryBus. The appropriate Handler will take care of retrieving the information we need and returning it in a structured form.
<?php
namespace PrestaShop\PrestaShop\Core\Form\IdentifiableObject\DataProvider;
use PrestaShop\PrestaShop\Core\CommandBus\CommandBusInterface;
use PrestaShop\PrestaShop\Core\Domain\Contact\DTO\EditableContact;
use PrestaShop\PrestaShop\Core\Domain\Contact\Exception\ContactException;
use PrestaShop\PrestaShop\Core\Domain\Contact\Query\GetContactForEditing;
final class ContactFormDataProvider implements FormDataProviderInterface
{
/**
* @var CommandBusInterface
*/
private $queryBus;
/**
* @param CommandBusInterface $queryBus
*/
public function __construct(CommandBusInterface $queryBus)
{
$this->queryBus = $queryBus;
}
/**
* {@inheritdoc}
*
* @throws ContactException
*/
public function getData($contactId)
{
/** @var EditableContact $editableContact */
$editableContact = $this->queryBus->handle(new GetContactForEditing($contactId));
return [
'title' => $editableContact->getLocalisedTitles(),
'email' => $editableContact->getEmail(),
'is_messages_saving_enabled' => $editableContact->isMessagesSavingEnabled(),
'description' => $editableContact->getLocalisedDescription(),
'shop_association' => $editableContact->getShopAssociation(),
];
}
}
In the example above, the Handle to the GetContactForEditing query returns an instance of EditableContact, which is an immutable Data Transfer Object (DTO) containing all the information we need.