People’s Postcode Lottery - PHP Workshop - March 2017
What Is It?
Behavioural Design Pattern
Encapsulate the behaviour of an action
What Is A Command Anyway?
Encapsulation of a Request
as an Object
Abstraction to an underlying
Domain Concept
class AddToBasketCommand
{
private $basketId;
private $item;
public function __construct($basketId, $item)
{
$this->basketId = $basketId;
$this->item = $item;
}
public function getBasketId()
{
return $this->basketId;
}
public function getItem()
{
return $this->item;
}
}
Simple!
Commands are just data structures, no behaviour themselves
Wait, didn’t you say they’re an abstraction of behaviour?
Yes! Behaviour is managed by the Handler!
Command Handlers
1 Command = 1 Handler
Handlers Manage Domain Logic
No More Object Saves In Controllers!
Don't do secondary actions in Handlers
class AddToBasketCommandHandler
{
private $repository;
public function __construct($basketRepository)
{
$this->repository = $basketRepository;
}
public function execute(AddToBasketCommand $command)
{
$basket = $this->repository->find(
$command->getBasketId()
);
$basket->addItem($command->getItem());
$basket->save();
}
}
Testing
Unit tests for handlers
Unit test handler collaborators
Integration test against Message Bus (sometimes...)
