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@michellesanver #phpday Using the Workflow component for e-commerce
 #phpday | 10th of May 2019

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@michellesanver #phpday “Learn the most by sharing your knowledge with others” - @coderabbi WIIIIE \o/

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@michellesanver #phpday Using the Workflow component for e-commerce

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@michellesanver #phpday Writing Good Code

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@michellesanver #phpday This talk assumes little knowledge

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@michellesanver #phpday This talk is… Open Source

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No content

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@michellesanver #phpday Michelle Sanver Colour and code addict

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@michellesanver #phpday Accent!?

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@michellesanver #phpday

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@michellesanver #phpday “It’s like Uber… 
 For shopping”

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@michellesanver #phpday Order API Challenges

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@michellesanver #phpday Keeping orders/prices up to date

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@michellesanver #phpday Making our consumers love us
 (Good error messages and documentation)

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@michellesanver #phpday Handling cancellation of an order

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@michellesanver #phpday Handling a large amount of SMS and Push notifications

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@michellesanver #phpday

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@michellesanver #phpday State Machines

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@michellesanver #phpday Why?

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@michellesanver #phpday GREEN YELLOW RED

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@michellesanver #phpday GREEN YELLOW RED

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@michellesanver #phpday GREEN YELLOW RED

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@michellesanver #phpday GREEN YELLOW RED

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@michellesanver #phpday GREEN YELLOW RED Timer

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@michellesanver #phpday GREEN YELLOW RED Timer T1

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@michellesanver #phpday GREEN YELLOW RED Timer T1 T1

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@michellesanver #phpday GREEN YELLOW RED Timer T1 T1 T1

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@michellesanver #phpday GREEN YELLOW RED Timer T1 T1 T1 T0

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@michellesanver #phpday GREEN YELLOW RED Timer T1 T1 T1 T0 T0 T0

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@michellesanver #phpday GREEN RED ;) BLUE

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@michellesanver #phpday GREEN YELLOW BLUE T1 T2 Workflow

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@michellesanver #phpday GREEN YELLOW BLUE T1 T2 State Machine T3

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@michellesanver #phpday We already think in states and workflows

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@michellesanver #phpday The Order
 State Machine

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@michellesanver #phpday Happy Workflow

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@michellesanver #phpday 1. An order is created Open

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@michellesanver #phpday 2. Items are updated Open

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@michellesanver #phpday 3. User sets delivery address on order. Open

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@michellesanver #phpday 4. User checks out Confirmed

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@michellesanver #phpday 5. Pickers get notified Confirmed

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@michellesanver #phpday 6. Picker accepts order Assigned To Picker

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@michellesanver #phpday 7. Picker goes shopping Picked Up

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@michellesanver #phpday 8. Picker delivers order Delivered

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@michellesanver #phpday 9. Card gets charged for order, picker gets paid Delivered

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@michellesanver #phpday Open Confirmed Assigned To Picker Picked Up Delivered Happy Workflow

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@michellesanver #phpday Cancelled Aborted

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@michellesanver #phpday Cancelled By System

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@michellesanver #phpday Open Confirmed Assigned To Picker Picked Up Delivered Cancelled Aborted Cancelled By System

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@michellesanver #phpday Open Confirmed Assigned To Picker Picked Up Delivered Cancelled Aborted Cancelled By System

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@michellesanver #phpday Open Confirmed Assigned To Picker Picked Up Delivered Cancelled Aborted Cancelled By System Cancel Order For technical Reasons Cancel Abort Checkout Assign to picker Pick Up Deliver Cancel Cancel Cancel

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@michellesanver #phpday Open Open UpdateItem

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@michellesanver #phpday State machines make business logic explicit

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@michellesanver #phpday Open Confirmed Assigned To Picker Picked Up Delivered Cancelled Aborted Cancelled By System Cancel Order For technical Reasons Cancel Abort Checkout Assign to picker Pick Up Deliver Cancel Cancel Cancel

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@michellesanver #phpday A workflow does not contain all logic

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@michellesanver #phpday The Workflow Component

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@michellesanver #phpday composer require symfony/workflow

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@michellesanver #phpday Our Workflow

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@michellesanver #phpday Open Confirmed Assigned To Picker Picked Up Delivered Cancelled Aborted Cancelled By System Cancel Order For technical Reasons Cancel Abort Checkout Assign to picker Pick Up Deliver Cancel Cancel Cancel

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@michellesanver #phpday framework: workflows: order: type: state_machine marking_store: type: 'single_state' arguments: - 'state' supports: - AppBundle\Entity\Order places: - open - confirmed - assigned-to-delivery-person - picked-up - delivered - aborted - cancelled transitions: updateItem: from: open to: open

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@michellesanver #phpday framework: workflows: order: type: state_machine marking_store: type: 'single_state' arguments: - 'state' supports: - AppBundle\Entity\Order

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@michellesanver #phpday framework: workflows: order: type: state_machine marking_store: type: 'single_state' arguments: - 'state' supports: - AppBundle\Entity\Order

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@michellesanver #phpday framework: workflows: order: type: state_machine marking_store: type: 'single_state' arguments: - 'state' supports: - AppBundle\Entity\Order

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@michellesanver #phpday framework: workflows: order: type: state_machine marking_store: type: 'single_state' arguments: - 'state' supports: - AppBundle\Entity\Order

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@michellesanver #phpday framework: workflows: order: type: state_machine marking_store: type: 'single_state' arguments: - 'state' supports: - AppBundle\Entity\Order

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@michellesanver #phpday places: - open - confirmed - assigned-to-picker - picked-up - delivered - aborted - cancelled - cancelled-by-system

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@michellesanver #phpday transitions: updateItem: from: open to: open

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@michellesanver #phpday The Model

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@michellesanver #phpday public const STATE_OPEN = 'open'; public const STATE_CONFIRMED = 'confirmed'; public const STATE_ASSIGNED_TO_PICKER = 'assigned-to-picker'; public const STATE_PICKED_UP = 'picked-up'; public const STATE_DELIVERED = 'delivered'; public const STATE_ABORTED_BY_CUSTOMER = 'aborted'; public const STATE_CANCELLED_BY_SUPPORT = 'cancelled'; public const STATE_CANCELLED_BY_SYSTEM = 'cancelled-by-system';

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@michellesanver #phpday public const STATES = [ self::STATE_OPEN, self::STATE_CONFIRMED, self::STATE_ASSIGNED_TO_PICKER, self::STATE_PICKED_UP, self::STATE_DELIVERED, self::STATE_ABORTED_BY_CUSTOMER, self::STATE_CANCELLED_BY_SUPPORT, self::STATE_CANCELLED_BY_SYSTEM, ];

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@michellesanver #phpday public const TRANSITION_UPDATE_ITEM = 'updateItem';

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@michellesanver #phpday /** * @var string */ private $state = self::STATE_OPEN;

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@michellesanver #phpday

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@michellesanver #phpday Events

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@michellesanver #phpday Solves Tight Coupling

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@michellesanver #phpday EventDispatcher

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@michellesanver #phpday composer require symfony/event-dispatcher

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@michellesanver #phpday The Listener

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@michellesanver #phpday class OrderWorkflowListener implements EventSubscriberInterface {
 … }

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@michellesanver #phpday /** * @return array Hashmap of Symfony events this handler cares about */ public static function getSubscribedEvents() { return [ // Guard events (Validate whether the transition is allowed at all) 'workflow.order.guard' => 'guardGeneralOrderWorkflow', sprintf('workflow.order.guard.%s', Order::TRANSITION_CHANGE_REGION) => 'guardChangeRegion', sprintf('workflow.order.guard.%s', Order::TRANSITION_CONFIRM_ORDER) => 'guardConfirmOrder', sprintf('workflow.order.guard.%s', Order::TRANSITION_ASSIGN_PICKER) => 'guardAssignPicker', sprintf('workflow.order.guard.%s', Order::TRANSITION_ASSIGN_CUSTOMER) => 'guardAssignCustomer', // Enter events (The object is about to enter a new place) sprintf('workflow.order.enter.%s', Order::STATE_CONFIRMED) => 'enterConfirmed', sprintf('workflow.order.enter.%s', Order::STATE_DELIVERED) => 'enterDelivered', // Entered events (The object entered a new place) sprintf('workflow.order.entered.%s', Order::STATE_PICKED_UP) => 'enteredPickedUp', // The object has completed this transition. 'workflow.order.completed' => 'onCompleted', ]; }

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@michellesanver #phpday /** * @return array Hashmap of Symfony events this handler cares about */ public static function getSubscribedEvents() { return [ // Guard events (Validate whether the transition is allowed at all) 'workflow.order.guard' => 'guardGeneralOrderWorkflow', sprintf('workflow.order.guard.%s', Order::TRANSITION_CHANGE_REGION) => 'guardChangeRegion', sprintf('workflow.order.guard.%s', Order::TRANSITION_CONFIRM_ORDER) => 'guardConfirmOrder', sprintf('workflow.order.guard.%s', Order::TRANSITION_ASSIGN_PICKER) => 'guardAssignPicker', sprintf('workflow.order.guard.%s', Order::TRANSITION_ASSIGN_CUSTOMER) => 'guardAssignCustomer', // Enter events (The object is about to enter a new place) sprintf('workflow.order.enter.%s', Order::STATE_CONFIRMED) => 'enterConfirmed', sprintf('workflow.order.enter.%s', Order::STATE_DELIVERED) => 'enterDelivered', // Entered events (The object entered a new place) sprintf('workflow.order.entered.%s', Order::STATE_PICKED_UP) => 'enteredPickedUp', // The object has completed this transition. 'workflow.order.completed' => 'onCompleted', ]; }

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@michellesanver #phpday /** * @return array Hashmap of Symfony events this handler cares about */ public static function getSubscribedEvents() { return [ // Guard events (Validate whether the transition is allowed at all) 'workflow.order.guard' => 'guardGeneralOrderWorkflow', sprintf('workflow.order.guard.%s', Order::TRANSITION_CHANGE_REGION) => 'guardChangeRegion', sprintf('workflow.order.guard.%s', Order::TRANSITION_CONFIRM_ORDER) => 'guardConfirmOrder', sprintf('workflow.order.guard.%s', Order::TRANSITION_ASSIGN_PICKER) => 'guardAssignPicker', sprintf('workflow.order.guard.%s', Order::TRANSITION_ASSIGN_CUSTOMER) => 'guardAssignCustomer', // Enter events (The object is about to enter a new place) sprintf('workflow.order.enter.%s', Order::STATE_CONFIRMED) => 'enterConfirmed', sprintf('workflow.order.enter.%s', Order::STATE_DELIVERED) => 'enterDelivered', // Entered events (The object entered a new place) sprintf('workflow.order.entered.%s', Order::STATE_PICKED_UP) => 'enteredPickedUp', // The object has completed this transition. 'workflow.order.completed' => 'onCompleted', ]; }

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@michellesanver #phpday /** * @return array Hashmap of Symfony events this handler cares about */ public static function getSubscribedEvents() { return [ // Guard events (Validate whether the transition is allowed at all) 'workflow.order.guard' => 'guardGeneralOrderWorkflow', sprintf('workflow.order.guard.%s', Order::TRANSITION_CHANGE_REGION) => 'guardChangeRegion', sprintf('workflow.order.guard.%s', Order::TRANSITION_CONFIRM_ORDER) => 'guardConfirmOrder', sprintf('workflow.order.guard.%s', Order::TRANSITION_ASSIGN_PICKER) => 'guardAssignPicker', sprintf('workflow.order.guard.%s', Order::TRANSITION_ASSIGN_CUSTOMER) => 'guardAssignCustomer', // Enter events (The object is about to enter a new place) sprintf('workflow.order.enter.%s', Order::STATE_CONFIRMED) => 'enterConfirmed', sprintf('workflow.order.enter.%s', Order::STATE_DELIVERED) => 'enterDelivered', // Entered events (The object entered a new place) sprintf('workflow.order.entered.%s', Order::STATE_PICKED_UP) => 'enteredPickedUp', // The object has completed this transition. 'workflow.order.completed' => 'onCompleted', ]; }

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@michellesanver #phpday /** * @return array Hashmap of Symfony events this handler cares about */ public static function getSubscribedEvents() { return [ // Guard events (Validate whether the transition is allowed at all) 'workflow.order.guard' => 'guardGeneralOrderWorkflow', sprintf('workflow.order.guard.%s', Order::TRANSITION_CHANGE_REGION) => 'guardChangeRegion', sprintf('workflow.order.guard.%s', Order::TRANSITION_CONFIRM_ORDER) => 'guardConfirmOrder', sprintf('workflow.order.guard.%s', Order::TRANSITION_ASSIGN_PICKER) => 'guardAssignPicker', sprintf('workflow.order.guard.%s', Order::TRANSITION_ASSIGN_CUSTOMER) => 'guardAssignCustomer', // Enter events (The object is about to enter a new place) sprintf('workflow.order.enter.%s', Order::STATE_CONFIRMED) => 'enterConfirmed', sprintf('workflow.order.enter.%s', Order::STATE_DELIVERED) => 'enterDelivered', // Entered events (The object entered a new place) sprintf('workflow.order.entered.%s', Order::STATE_PICKED_UP) => 'enteredPickedUp', // The object has completed this transition. 'workflow.order.completed' => 'onCompleted', ]; }

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@michellesanver #phpday Workflow component does so much for us

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@michellesanver #phpday Order API Challenges Solved

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@michellesanver #phpday Keeping orders/prices up to date

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@michellesanver #phpday public function onCompleted(Event $event): void { $transition = $event->getTransition(); $fromState = $transition->getFroms()[0]; /** @var Order $order */ $order = $event->getSubject(); // If an order is already in delivered state, all calculations are done, and should stay as they are. if (Order::STATE_DELIVERED !== $fromState) { $this->orderModifier->updateTotals($order); } $this->orderStateHistoryRepository->storeOrderStateTransition($order, $transition); $this->orderEventService->eventHappened($transition->getName(), $order->getId(), $fromState); }

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@michellesanver #phpday public function onCompleted(Event $event): void { $transition = $event->getTransition(); $fromState = $transition->getFroms()[0]; /** @var Order $order */ $order = $event->getSubject(); // If an order is already in delivered state, all calculations are done, and should stay as they are. if (Order::STATE_DELIVERED !== $fromState) { $this->orderModifier->updateTotals($order); } $this->orderStateHistoryRepository->storeOrderStateTransition($order, $transition); $this->orderEventService->eventHappened($transition->getName(), $order->getId(), $fromState); }

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@michellesanver #phpday if (Order::STATE_DELIVERED !== $fromState) { $this->orderModifier->updateTotals($order); }

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@michellesanver #phpday Making our consumers love us
 (Good error messages and documentation)

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@michellesanver #phpday Handling cancellation of an order

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@michellesanver #phpday Handling a large amount of SMS and Push notifications

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@michellesanver #phpday public function onCompleted(Event $event): void { $transition = $event->getTransition(); $fromState = $transition->getFroms()[0]; /** @var Order $order */ $order = $event->getSubject(); // If an order is already in delivered state, all calculations are done, and should stay as they are. if (Order::STATE_DELIVERED !== $fromState) { $this->orderModifier->updateTotals($order); } $this->orderStateHistoryRepository->storeOrderStateTransition($order, $transition); $this->orderEventService->eventHappened($transition->getName(), $order->getId(), $fromState); }

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@michellesanver #phpday public function onCompleted(Event $event): void { $transition = $event->getTransition(); $fromState = $transition->getFroms()[0]; /** @var Order $order */ $order = $event->getSubject(); // If an order is already in delivered state, all calculations are done, and should stay as they are. if (Order::STATE_DELIVERED !== $fromState) { $this->orderModifier->updateTotals($order); } $this->orderStateHistoryRepository->storeOrderStateTransition($order, $transition); $this->orderEventService->eventHappened($transition->getName(), $order->getId(), $fromState); }

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@michellesanver #phpday $this->orderEventService->eventHappened($transition->getName(), $order->getId(), $fromState);

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@michellesanver #phpday public function eventHappened(string $type, string $orderId, ?string $previousState) { foreach ($this->handlers as $handler) { if ($handler->canHandle($type)) { $this->orderEventProducer->publish( $type, $orderId, $previousState, $handler->getPriority() ); return; } } }

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@michellesanver #phpday public function eventHappened(string $type, string $orderId, ?string $previousState) { foreach ($this->handlers as $handler) { if ($handler->canHandle($type)) { $this->orderEventProducer->publish( $type, $orderId, $previousState, $handler->getPriority() ); return; } } }

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@michellesanver #phpday class SmsNotificationHandler implements OrderEventHandler { private const TRANSITION_STATE_MAP = [ Order::TRANSITION_ASSIGN_PICKER => Order::STATE_ASSIGNED_TO_PICKER, Order::TRANSITION_TIMEOUT_FINDING_PICKER => Order::STATE_ABORTED_BY_CUSTOMER, Order::TRANSITION_PICKER_CONFIRMS_PURCHASE => Order::STATE_PICKED_UP, Order::TRANSITION_CONFIRM_DELIVERY => Order::STATE_DELIVERED, Order::TRANSITION_REFERRAL_PICKER_RECEIVES_REWARD => Order::STATE_DELIVERED, Order::TRANSITION_SEND_ORDER_AVAILABLE_REMINDER => Order::STATE_CONFIRMED, ];

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@michellesanver #phpday public function canHandle(string $type): bool { return array_key_exists($type, self::TRANSITION_STATE_MAP); }

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@michellesanver #phpday Conclusion

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@michellesanver #phpday We already think in states and workflows

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@michellesanver #phpday State machines make business logic explicit

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@michellesanver #phpday Workflow component does so much for us!

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@michellesanver #phpday Writing Good Code

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@michellesanver #phpday This talk is for you Questions? Contributions?

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@michellesanver #phpday Thank You #phpday! https://joind.in/talk/caf64