Lookup

baseline.xml

@@ -145,6 +145,11 @@
       <code><![CDATA[SubscriberAccessor|null]]></code>
     </DeprecatedInterface>
   </file>
+  <file src="src/Subscription/Lookup/Lookup.php">
+    <ArgumentTypeCoercion>
+      <code><![CDATA[$event]]></code>
+    </ArgumentTypeCoercion>
+  </file>
   <file src="src/Subscription/Store/DoctrineSubscriptionStore.php">
     <MixedArgument>
       <code><![CDATA[$context]]></code>

docs/pages/subscription.md

@@ -215,6 +215,65 @@ final class DoStuffSubscriber
     }
 }
 ```
+##### Lookup Resolver
+
+Sometimes you need to query previous events to build a projection.
+For this you can use the `Lookup` service.
+This service only has access to the messages before the current message.
+Here is an example how you can use it in a projector.
+
+```php
+use Patchlevel\EventSourcing\Attribute\Subscribe;
+use Patchlevel\EventSourcing\Message\Reducer;
+use Patchlevel\EventSourcing\Subscription\Lookup;
+
+#[Projector('public_profile')]
+final class PublicProfileProjection
+{
+    use SubscriberUtil;
+
+    // ... constructor
+
+    #[Subscribe(Published::class)]
+    public function onPublished(Lookup $lookup): void
+    {
+        $messages = $lookup
+            ->currentAggregate() // or ->currentStream() for StreamStore
+            ->events(
+                ProfileCreated::class,
+                ProfileNameChanged::class,
+            )->fetchAll();
+
+        $state = (new Reducer())
+            ->initState([
+                'id' => null,
+                'name' => null,
+            ])
+            ->match([
+                ProfileCreated::class => static function (Message $message): array {
+                    return [
+                        'id' => $message->event()->id->toString(),
+                        'name' => $message->event()->name,
+                    ];
+                },
+                ProfileNameChanged::class => static function (Message $message, array $prevState): array {
+                    return array_merge($prevState, [
+                        'name' => $message->event()->name,
+                    ]);
+                },
+            ])
+            ->reduce($messages);
+
+        $this->connection->insert('public_profile', $state);
+    }
+
+    // ... setup, teardown, ...
+}
+```
+!!! note
+
+    More about reducers you can find [here](./message.md#reducer)
+
 ##### Aggregate Id Resolver
 
 The aggregate id resolver resolves the aggregate id.

phpstan-baseline.neon

@@ -132,6 +132,12 @@ parameters:
 			count: 1
 			path: src/Store/StreamDoctrineDbalStoreStream.php
 
+		-
+			message: '#^Parameter \#1 \$eventClass of method Patchlevel\\EventSourcing\\Metadata\\Event\\EventRegistry\:\:eventName\(\) expects class\-string, string given\.$#'
+			identifier: argument.type
+			count: 1
+			path: src/Subscription/Lookup/Lookup.php
+
 		-
 			message: '#^Strict comparison using \=\=\= between DateTimeImmutable and false will always evaluate to false\.$#'
 			identifier: identical.alwaysFalse

src/Serializer/DefaultEventSerializer.php

@@ -18,8 +18,8 @@ final class DefaultEventSerializer implements EventSerializer
 {
     public function __construct(
         private EventRegistry $eventRegistry,
-        private Hydrator $hydrator,
-        private Encoder $encoder,
+        private Hydrator $hydrator = new MetadataHydrator(),
+        private Encoder $encoder = new JsonEncoder(),
         private Upcaster|null $upcaster = null,
     ) {
     }

src/Store/Criteria/ToIndexCriterion.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\Store\Criteria;
+
+final class ToIndexCriterion
+{
+    public function __construct(
+        public readonly int $toIndex,
+    ) {
+    }
+}

src/Store/DoctrineDbalStore.php

@@ -30,6 +30,8 @@
 use Patchlevel\EventSourcing\Store\Criteria\EventsCriterion;
 use Patchlevel\EventSourcing\Store\Criteria\FromIndexCriterion;
 use Patchlevel\EventSourcing\Store\Criteria\FromPlayheadCriterion;
+use Patchlevel\EventSourcing\Store\Criteria\ToIndexCriterion;
+use Patchlevel\EventSourcing\Store\Header\IndexHeader;
 use PDO;
 
 use function array_fill;
@@ -155,8 +157,12 @@
                     $builder->setParameter('archived', $criterion->archived, Types::BOOLEAN);
                     break;
                 case FromIndexCriterion::class:
-                    $builder->andWhere('id > :index');
-                    $builder->setParameter('index', $criterion->fromIndex, Types::INTEGER);
+                    $builder->andWhere('id > :fromIndex');
+                    $builder->setParameter('fromIndex', $criterion->fromIndex, Types::INTEGER);
+                    break;
+                case ToIndexCriterion::class:
+                    $builder->andWhere('id < :toIndex');
+                    $builder->setParameter('toIndex', $criterion->toIndex, Types::INTEGER);
                     break;
                 case EventsCriterion::class:
                     $builder->andWhere('event IN (:events)');
@@ -351,7 +357,8 @@
     /** @return list<object> */
     private function getCustomHeaders(Message $message): array
     {
         $filteredHeaders = [
+            IndexHeader::class,
             AggregateHeader::class,
             StreamStartHeader::class,
             ArchivedHeader::class,

src/Store/DoctrineDbalStoreStream.php

@@ -15,6 +15,7 @@
 use Patchlevel\EventSourcing\Message\Serializer\HeadersSerializer;
 use Patchlevel\EventSourcing\Serializer\EventSerializer;
 use Patchlevel\EventSourcing\Serializer\SerializedEvent;
+use Patchlevel\EventSourcing\Store\Header\IndexHeader;
 use Traversable;
 
 /** @implements IteratorAggregate<Message> */
@@ -125,6 +126,7 @@ private function buildGenerator(
             $event = $eventSerializer->deserialize(new SerializedEvent($data['event'], $data['payload']));
 
             $message = Message::create($event)
+                ->withHeader(new IndexHeader($data['id']))
                 ->withHeader(new AggregateHeader(
                     $data['aggregate'],
                     $data['aggregate_id'],

src/Store/Header/IndexHeader.php

@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\Store\Header;
+
+/**
+ * @psalm-immutable
+ * @experimental
+ */
+final class IndexHeader
+{
+    /** @param positive-int $index */
+    public function __construct(
+        public readonly int $index,
+    ) {
+    }
+}

src/Store/StreamDoctrineDbalStore.php

@@ -29,8 +29,10 @@
 use Patchlevel\EventSourcing\Store\Criteria\FromIndexCriterion;
 use Patchlevel\EventSourcing\Store\Criteria\FromPlayheadCriterion;
 use Patchlevel\EventSourcing\Store\Criteria\StreamCriterion;
+use Patchlevel\EventSourcing\Store\Criteria\ToIndexCriterion;
 use Patchlevel\EventSourcing\Store\Criteria\ToPlayheadCriterion;
 use Patchlevel\EventSourcing\Store\Header\EventIdHeader;
+use Patchlevel\EventSourcing\Store\Header\IndexHeader;
 use Patchlevel\EventSourcing\Store\Header\PlayheadHeader;
 use Patchlevel\EventSourcing\Store\Header\RecordedOnHeader;
 use Patchlevel\EventSourcing\Store\Header\StreamNameHeader;
@@ -186,11 +188,15 @@
                     $builder->setParameter('archived', $criterion->archived, Types::BOOLEAN);
                     break;
                 case FromIndexCriterion::class:
-                    $builder->andWhere('id > :index');
-                    $builder->setParameter('index', $criterion->fromIndex, Types::INTEGER);
+                    $builder->andWhere('id > :from_index');
+                    $builder->setParameter('from_index', $criterion->fromIndex, Types::INTEGER);
+                    break;
+                case ToIndexCriterion::class:
+                    $builder->andWhere('id < :to_index');
+                    $builder->setParameter('to_index', $criterion->toIndex, Types::INTEGER);
                     break;
                 case EventsCriterion::class:
-                    $builder->andWhere('event IN (:events)');
+                    $builder->andWhere('event_name IN (:events)');
                     $builder->setParameter('events', $criterion->events, ArrayParameterType::STRING);
                     break;
                 default:
@@ -333,7 +339,7 @@
         return $streams;
     }
 
     public function remove(Criteria|null $criteria = null): void
     {
         $builder = $this->connection->createQueryBuilder();
 
@@ -398,7 +404,8 @@
     /** @return list<object> */
     private function getCustomHeaders(Message $message): array
     {
         $filteredHeaders = [
+            IndexHeader::class,
             StreamNameHeader::class,
             EventIdHeader::class,
             PlayheadHeader::class,

src/Store/StreamDoctrineDbalStoreStream.php

@@ -16,6 +16,7 @@
 use Patchlevel\EventSourcing\Serializer\EventSerializer;
 use Patchlevel\EventSourcing\Serializer\SerializedEvent;
 use Patchlevel\EventSourcing\Store\Header\EventIdHeader;
+use Patchlevel\EventSourcing\Store\Header\IndexHeader;
 use Patchlevel\EventSourcing\Store\Header\PlayheadHeader;
 use Patchlevel\EventSourcing\Store\Header\RecordedOnHeader;
 use Patchlevel\EventSourcing\Store\Header\StreamNameHeader;
@@ -130,6 +131,7 @@ private function buildGenerator(
             $event = $eventSerializer->deserialize(new SerializedEvent($data['event_name'], $data['event_payload']));
 
             $message = Message::create($event)
+                ->withHeader(new IndexHeader($data['id']))
                 ->withHeader(new StreamNameHeader($data['stream']))
                 ->withHeader(new RecordedOnHeader($dateTimeType->convertToPHPValue($data['recorded_on'], $platform)))
                 ->withHeader(new EventIdHeader($data['event_id']));