This presentation is about real examples of Design Patterns usage in Magento 2. There are 2 major architectural goals set for Magento 2 project: 1. Enable streamline customisations. 2. Simplify external integrations. There are much more Design Patterns used in Magento 2, some of them are discussed in the deck.

1. MAGENTO 2 DESIGN PATTERNS
by Max Pronko
Magento Meetup Dublin 13February 9, 2016

2. ABOUT ME
➤ 6 years with Magento
➤ Magento 2 Blogger
➤ Father
➤ from Ukraine
➤ CTO @ GiftsDirect

3. MAGENTO 2 ARCHITECTURE DESIGN GOALS
What:
➤ Streamline customisations
➤ Simplify external integrations
How:
➤ Loose coupling between Modules
➤ SOLID Principles
➤ Design Patterns
➤ Configuration over customisation
3

4. S.O.L.I.D.
Principles
4

5. SINGLE RESPONSIBILITY PRINCIPLE
➤ Class should have only 1 reason to change.
namespace MagentoCmsControllerPage;
class View extends MagentoFrameworkAppActionAction
{
/** code */
public function execute()
{
$pageId = $this->getRequest()->getParam('page_id', $this->getRequest()->getParam('id', false));
$resultPage = $this->_objectManager->get('MagentoCmsHelperPage')->prepareResultPage($this,
$pageId);
if (!$resultPage) {
$resultForward = $this->resultForwardFactory->create();
return $resultForward->forward('noroute');
}
return $resultPage;
}
}
5

6. OPEN/CLOSED PRINCIPLE
➤ Classes should be open for extension, but closed for
modification.
namespace MagentoCatalogControllerAdminhtmlCategory;
class RefreshPath extends MagentoCatalogControllerAdminhtmlCategory
{
/** code */
public function execute()
{
$categoryId = (int)$this->getRequest()->getParam('id');
if ($categoryId) {
$category = $this->_objectManager->create('MagentoCatalogModelCategory')->load($categoryId);
/** @var MagentoFrameworkControllerResultJson $resultJson */
$resultJson = $this->resultJsonFactory->create();
return $resultJson->setData(['id' => $categoryId, 'path' => $category->getPath()]);
}
}
}
6

7. LISKOV SUBSTITUTION PRINCIPLE
Source: https://lostechies.com

8. INTERFACE SEGREGATION PRINCIPLE
➤ Client should not be forced to depend on methods it does not
use.
namespace MagentoPaymentGatewayHttp;
interface TransferInterface
{
public function getClientConfig();
public function getMethod();
public function getHeaders();
public function shouldEncode(); //Client Zend
public function getBody();
public function getUri(); //Client Zend
public function getAuthUsername(); // None
public function getAuthPassword(); // None
}
namespace MagentoPaymentGatewayHttpTransfer;
interface AuthInterface
{
public function getUsername();
public function getPassword();
}
interface ZendUrlEncoderInterface
{
public function shouldEncode();
}
interface ConfigInterface
{
public function getValue();
}
namespace MagentoPaymentGatewayHttp;
interface TransferInterface
{
public function getMethod();
public function getHeaders();
public function getBody();
}
Decoupling example
8
Might be improved

9. DEPENDENCY INVERSION PRINCIPLE
➤ High-level modules should not depend on low-level modules.
Both should depend on abstractions.namespace MagentoFramework;
class Image
{
/**
* @var ImageAdapterAdapterInterface
*/
protected $_adapter;
public function __construct(
MagentoFrameworkImageAdapterAdapterInterface $adapter,
$fileName = null
) {
$this->_adapter = $adapter;
$this->_fileName = $fileName;
if (isset($fileName)) {
$this->open();
}
}
/** code */
}
9

10. SOME TIPS
➤ Create tiny classes to avoid
monsters
➤ Build your code on
abstractions (interfaces)
➤ Look inside code for good
practices
➤ Refactor, refactor, refactor
10

11. DESIGN
PATTERNS
Magento 2 Edition

12. “Each pattern describes a problem which occurs over and over
again in our environment, and then describes the core of the
solution to that problem, in such a way that you can use this
solution a million times over, without ever doing it the same
way twice
-Christopher Alexander
DESIGN PATTERNS
12

13. MAGENTO 2 DESIGN PATTERNS

14. OBJECT MANAGER
➤ Dependency Injection Manager
➤ Knows how to instantiate classes
➤ Creates objects
➤ Provides shared pool of objects
➤ Enables lazy initialisation

15. OBJECT MANAGER
15
Patterns:
➤ Dependency Injection
➤ Singleton
➤ Builder
➤ Abstract Factory
➤ Factory Method
➤ Decorator
➤ Value Object
➤ Composition
➤ Strategy
➤ CQRS (command query responsibility segregation)
➤ more…

16. OBJECT MANAGER
Magento/Framework
16

17. FACTORY METHOD
17
namespace MagentoCatalogModel;
class Factory
{
protected $_objectManager;
public function __construct(MagentoFrameworkObjectManagerInterface $objectManager)
{
$this->_objectManager = $objectManager;
}
public function create($className, array $data = [])
{
$model = $this->_objectManager->create($className, $data);
if (!$model instanceof MagentoFrameworkModelAbstractModel) {
throw new MagentoFrameworkExceptionLocalizedException(
__('%1 doesn't extends MagentoFrameworkModelAbstractModel', $className)
);
}
return $model;
}
}
➤ Creates family of related objects.

18. FACTORY METHOD
MagentoFrameworkMagentoCatalogModel

19. OBSERVER
namespace MagentoCatalogModel;
use MagentoCatalogApiDataProductInterface;
use MagentoFrameworkDataObjectIdentityInterface;
use MagentoFrameworkPricingSaleableInterface;
class Product extends MagentoCatalogModelAbstractModel implements
IdentityInterface,
SaleableInterface,
ProductInterface
{
protected $_eventPrefix = 'catalog_product';
public function validate()
{
$this->_eventManager->dispatch($this->_eventPrefix . '_validate_before', $this->_getEventData());
$result = $this->_getResource()->validate($this);
$this->_eventManager->dispatch($this->_eventPrefix . '_validate_after', $this->_getEventData());
return $result;
}
}
File: MeetupModuleetcadminhtmlevents.xml
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
<event name="catalog_product_validate_before">
<observer name="meetup_module_product_validator" instance="MeetupModuleObserverProductObserver" />
</event>
</config>

20. OBSERVER
Domain Model Framework
20
➤ Distributed event handling system.

21. PROXY
File: app/code/Magento/Catalog/etc/di.xml
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
<type name="MagentoCatalogModelResourceModelProductCollection">
<arguments>
<argument name="catalogUrl" xsi:type="object">MagentoCatalogModelResourceModelUrlProxy</argument>
<argument name="customerSession" xsi:type="object">MagentoCustomerModelSessionProxy</argument>
</arguments>
</type>
</config>
➤ Support for resource consuming objects.
21

22. PROXY
namespace MagentoCatalogModelResourceModelUrl;
use MagentoFrameworkObjectManagerInterface;
class Proxy extends MagentoCatalogModelResourceModelUrl
{
public function __construct(
ObjectManagerInterface $objectManager,
$instanceName = 'MagentoCatalogModelResourceModelUrl',
$shared = true
) {
$this->_objectManager = $objectManager;
$this->_instanceName = $instanceName;
$this->_isShared = $shared;
}
protected function _getSubject()
{
if (!$this->_subject) {
$this->_subject = true === $this->_isShared
? $this->_objectManager->get($this->_instanceName)
: $this->_objectManager->create($this->_instanceName);
}
return $this->_subject;
}
public function _getProductAttribute($attributeCode, $productIds, $storeId)
{
return $this->_getSubject()->_getProductAttribute($attributeCode, $productIds, $storeId);
}
public function load(MagentoFrameworkModelAbstractModel $object, $value, $field = null)
{
return $this->_getSubject()->load($object, $value, $field);
}
}

23. COMPOSITE
namespace MagentoPaymentGatewayRequest;
use MagentoFrameworkObjectManagerTMap;
use MagentoFrameworkObjectManagerTMapFactory;
class BuilderComposite implements BuilderInterface
{
private $builders;
public function __construct(
TMapFactory $tmapFactory,
array $builders = []
) {
$this->builders = $tmapFactory->create(
[
'array' => $builders,
'type' => BuilderInterface::class
]
);
}
public function build(array $buildSubject)
{
$result = [];
foreach ($this->builders as $builder) {
$result = $this->merge($result, $builder->build($buildSubject));
}
return $result;
}
protected function merge(array $result, array $builder)
{
return array_replace_recursive($result, $builder);
}
}

24. COMPOSITE
Magento/Payment/Gateway

25. #Thanks
Q&A
/maxpronkocom @max_pronkowww.maxpronko.com

26. MAGENTO 2 DESIGN PATTERNS
➤ Object Manager
➤ Event Observer
➤ Composition
➤ Factory Method
➤ Singleton
➤ Builder
➤ Factory
➤ State
➤ Strategy
➤ Adapter
➤ Command
➤ CQRS
➤ MVVM