Event Store Generator

Creates Event Store infrastructure for event sourcing with aggregate history and event replay.

When to Use

Scenario	Example
Event sourcing	Aggregate state from events
Audit trail	Complete change history
Event replay	Rebuild projections from events
Temporal queries	Query state at any point in time

Component Characteristics

StoredEvent

• Immutable event wrapper
• Contains aggregate metadata (id, type, version)
• Serialized payload
• Creation timestamp

EventStream

• Ordered collection of stored events
• Implements IteratorAggregate
• Tracks current version
• Supports appending new events

EventStoreInterface

• Append events with optimistic locking
• Load full event stream for aggregate
• Load events from specific version
• Stream-based reading for large aggregates

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Generation Process

Step 1: Generate Domain Components

Path: src/Domain/{BoundedContext}/EventStore/

1. StoredEvent.php — Immutable stored event value object
2. EventStreamInterface.php — Event stream contract
3. EventStream.php — Event stream implementation
4. EventStoreInterface.php — Event store contract

Step 2: Generate Infrastructure

Path: src/Infrastructure/{BoundedContext}/EventStore/

1. DoctrineEventStore.php — Doctrine DBAL implementation with optimistic locking
2. Database migration SQL

Step 3: Generate Tests

1. StoredEventTest.php — Stored event immutability tests
2. EventStreamTest.php — Stream operations tests
3. DoctrineEventStoreTest.php — Integration tests

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File Placement

Component	Path
StoredEvent	src/Domain/{BoundedContext}/EventStore/
EventStream	src/Domain/{BoundedContext}/EventStore/
EventStoreInterface	src/Domain/{BoundedContext}/EventStore/
DoctrineEventStore	src/Infrastructure/{BoundedContext}/EventStore/
Unit Tests	tests/Unit/Domain/{BoundedContext}/EventStore/
Integration Tests	tests/Integration/Infrastructure/{BoundedContext}/EventStore/

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Naming Conventions

Component	Pattern	Example
Stored Event	StoredEvent	StoredEvent
Stream Interface	EventStreamInterface	EventStreamInterface
Stream	EventStream	EventStream
Store Interface	EventStoreInterface	EventStoreInterface
Store Impl	Doctrine{Name}EventStore	DoctrineEventStore
Exception	ConcurrencyException	ConcurrencyException
Test	{ClassName}Test	StoredEventTest

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Quick Template Reference

StoredEvent

final readonly class StoredEvent
{
    public function __construct(
        public string $aggregateId,
        public string $aggregateType,
        public string $eventType,
        public string $payload,
        public int $version,
        public \DateTimeImmutable $createdAt
    ) {}

    public static function fromDomainEvent(string $aggregateId, string $aggregateType, int $version, object $event): self;
    public function toArray(): array;
    public static function fromArray(array $data): self;
}

EventStoreInterface

interface EventStoreInterface
{
    public function append(string $aggregateId, EventStream $events, int $expectedVersion): void;
    public function load(string $aggregateId): EventStream;
    public function loadFromVersion(string $aggregateId, int $fromVersion): EventStream;
}

EventStream

final class EventStream implements \IteratorAggregate, \Countable
{
    public static function empty(): self;
    public static function fromEvents(array $events): self;
    public function append(StoredEvent $event): self;
    public function getVersion(): int;
    public function isEmpty(): bool;
    public function getIterator(): \ArrayIterator;
    public function count(): int;
}

---

Usage Example

// Append events
$events = EventStream::fromEvents([
    StoredEvent::fromDomainEvent($orderId, 'Order', 1, $orderCreated),
    StoredEvent::fromDomainEvent($orderId, 'Order', 2, $itemAdded),
]);
$eventStore->append($orderId, $events, expectedVersion: 0);

// Load and replay
$stream = $eventStore->load($orderId);
foreach ($stream as $event) {
    $aggregate->apply($event);
}

---

Database Schema

CREATE TABLE event_store (
    id BIGINT AUTO_INCREMENT PRIMARY KEY,
    aggregate_id VARCHAR(36) NOT NULL,
    aggregate_type VARCHAR(255) NOT NULL,
    event_type VARCHAR(255) NOT NULL,
    payload JSON NOT NULL,
    version INT NOT NULL,
    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,

    UNIQUE INDEX idx_aggregate_version (aggregate_id, version),
    INDEX idx_aggregate_type (aggregate_type),
    INDEX idx_event_type (event_type),
    INDEX idx_created_at (created_at)
);

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Anti-patterns to Avoid

Anti-pattern	Problem	Solution
Mutable Events	History changes	Immutable StoredEvent
Missing Version	No optimistic locking	Version per aggregate
No Idempotency	Duplicate appends	Unique aggregate_id + version
Large Payloads	Slow reads	Serialize only essential data
No Snapshots	Slow rebuilds for long streams	Use create-snapshot
Global Stream Only	Can't load per-aggregate	Per-aggregate stream support

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References

For complete PHP templates and examples, see:

• references/templates.md — StoredEvent, EventStream, EventStoreInterface, DoctrineEventStore templates
• references/examples.md — Order event store usage and tests