Read layer usage in Write layer (example)

composer.json

@@ -3,7 +3,7 @@
     "type": "project",
     "license": "proprietary",
     "require": {
-        "php": ">=8.1",
+        "php": ">=8.2",
         "ext-ctype": "*",
         "ext-iconv": "*",
         "ext-json": "*",

config/services.yaml

@@ -16,6 +16,7 @@ services:
             Symfony\Component\Messenger\MessageBusInterface $projectionBus: "@projection.bus"
 
             Redis: '@snc_redis.default'
+            string $filePath: "%kernel.project_dir%/data/authors-with-more-than-thousand-followers.txt"
 
     # makes classes in src/ available to be used as services
     # this creates a service per class whose id is the fully-qualified class name
@@ -186,4 +187,7 @@ services:
             - name: "doctrine.orm.entity_listener"
               event: "postPersist"
               entity: 'App\Entity\User'
+
+    Cheeper\Chapter9\DomainModel\Author\AuthorsWithMoreThanAThousandOfFollowers:
+        class: 'Cheeper\Chapter9\Infrastructure\DomainModel\Author\TextFileAuthorsWithMoreThanAThousandOfFollowers'
 #end-ignore

data/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

src/Cheeper/Chapter9/Application/Author/Command/UpgradeAuthorsWithMoreThanAThousandOfFollowersCommand.php

@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Cheeper\Chapter9\Application\Author\Command;
+
+final readonly class UpgradeAuthorsWithMoreThanAThousandOfFollowersCommand
+{
+    public function __construct()
+    {
+    }
+}

src/Cheeper/Chapter9/Application/Author/Command/UpgradeAuthorsWithMoreThanAThousandOfFollowersCommandHandler.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Cheeper\Chapter9\Application\Author\Command;
+
+use Cheeper\Chapter9\DomainModel\Author\AuthorRepository;
+use Cheeper\Chapter9\DomainModel\Author\AuthorsWithMoreThanAThousandOfFollowers;
+
+final readonly class UpgradeAuthorsWithMoreThanAThousandOfFollowersCommandHandler
+{
+    public function __construct(
+        private AuthorRepository $authors,
+        private AuthorsWithMoreThanAThousandOfFollowers $authorsWithMoreThanAThousandOfFollowers
+    ) {
+    }
+
+    public function __invoke(UpgradeAuthorsWithMoreThanAThousandOfFollowersCommand $command): void
+    {
+        $authorsWithMoreThanAThousandOfFollowers = $this->authorsWithMoreThanAThousandOfFollowers;
+        $authorIds = $authorsWithMoreThanAThousandOfFollowers();
+
+        foreach ($authorIds as $authorId) {
+            $author = $this->authors->ofId($authorId);
+            $author->upgrade();
+            $this->authors->save($author);
+        }
+    }
+}

src/Cheeper/Chapter9/Application/Author/Event/WhenAuthorFollowedThenListAuthorsWithMoreThanThousandFollowersEventHandler.php

@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+
+namespace Cheeper\Chapter9\Application\Author\Event;
+
+use Cheeper\AllChapters\DomainModel\Author\AuthorId;
+use Cheeper\Chapter7\Application\Author\Projection\IncrementCountFollowersProjection;
+use Cheeper\Chapter7\Application\ProjectionBus;
+use Cheeper\Chapter8\DomainModel\Follow\AuthorFollowed;
+use Cheeper\Chapter8\DomainModel\Follow\FollowRepository;
+
+final readonly class WhenAuthorFollowedThenListAuthorsWithMoreThanThousandFollowersEventHandler
+{
+    public function __construct(
+        private ProjectionBus $projectionBus,
+        private FollowRepository $followRepository
+    ) {
+    }
+
+    public function __invoke(AuthorFollowed $event): void
+    {
+        if ($this->followRepository->numberOfFollowersFor(AuthorId::fromString($event->toAuthorId())) >= 1000) {
+            $this->projectionBus->project(
+                IncrementCountFollowersProjection::ofAuthor(
+                    $event->toAuthorId()
+                )
+            );
+        }
+    }
+}

src/Cheeper/Chapter9/Application/Author/Projection/AddAuthorToListOfAuthorsWithMoreThanThousandFollowersProjection.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+
+namespace Cheeper\Chapter9\Application\Author\Projection;
+
+final readonly class AddAuthorToListOfAuthorsWithMoreThanThousandFollowersProjection
+{
+    public function __construct(
+        public string $authorId
+    ) {
+    }
+}

src/Cheeper/Chapter9/Application/Author/Projection/AddAuthorToListOfAuthorsWithMoreThanThousandFollowersProjectionHandler.php

@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+
+namespace Cheeper\Chapter9\Application\Author\Projection;
+
+final readonly class AddAuthorToListOfAuthorsWithMoreThanThousandFollowersProjectionHandler
+{
+    public function __construct(
+        private string $filePath
+    ) {
+    }
+
+    public function __invoke(AddAuthorToListOfAuthorsWithMoreThanThousandFollowersProjection $projection): void
+    {
+        file_put_contents($this->filePath, $projection->authorId . PHP_EOL, FILE_APPEND);
+    }
+}

src/Cheeper/Chapter9/DomainModel/Author/Author.php

@@ -21,14 +21,15 @@ final class Author
 {
     use EventSourcedTrait;
 
-    private string             $authorId;
-    private string             $userName;
-    private string             $email;
-    private ?string            $name = null;
-    private ?string            $biography = null;
-    private ?string            $location = null;
-    private ?string            $website = null;
-    private ?DateTimeImmutable $birthDate = null;
+    private string              $authorId;
+    private string              $userName;
+    private string              $email;
+    private ?string             $name = null;
+    private ?string             $biography = null;
+    private ?string             $location = null;
+    private ?string             $website = null;
+    private ?DateTimeImmutable  $birthDate = null;
+    private bool                $upgraded = false;
 
     private function __construct()
     {
@@ -119,6 +120,13 @@ protected function applyThat(DomainEvent $event): void
         $this->$modifier($event);
     }
 
+    public function upgrade(): void
+    {
+        $this->recordApplyAndPublishThat(
+            new AuthorWasUpgraded($this->authorId)
+        );
+    }
+
     protected function applyNewAuthorSigned(NewAuthorSigned $event)
     {
         $this->authorId = $event->authorId();
@@ -136,6 +144,11 @@ protected function applyAuthorEmailChangedSigned(AuthorEmailChanged $event)
         $this->email = $event->authorEmail();
     }
 
+    private function applyAuthorWasUpgraded(): void
+    {
+        $this->upgraded = true;
+    }
+
     public function authorId(): AuthorId
     {
         return AuthorId::fromString($this->authorId);
@@ -176,6 +189,11 @@ public function birthDate(): ?BirthDate
         return $this->birthDate !== null ? BirthDate::fromString($this->birthDate->format('Y-m-d')) : null;
     }
 
+    public function upgraded(): bool
+    {
+        return $this->upgraded;
+    }
+
     //...
 }
 // end-snippet

src/Cheeper/Chapter9/DomainModel/Author/AuthorRepository.php

@@ -10,6 +10,6 @@
 interface AuthorRepository
 {
     public function ofId(AuthorId $authorId): ?Author;
-    public function add(Author $author): void;
+    public function save(Author $author): void;
 }
 //end-snippet

src/Cheeper/Chapter9/DomainModel/Author/AuthorWasUpgraded.php

@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+
+namespace Cheeper\Chapter9\DomainModel\Author;
+
+use Cheeper\Chapter7\Application\MessageTrait;
+use Cheeper\Chapter7\DomainModel\DomainEvent;
+
+final readonly class AuthorWasUpgraded implements DomainEvent
+{
+    use MessageTrait;
+
+    public function __construct(
+        public string $authorId
+    ) {
+    }
+}

src/Cheeper/Chapter9/DomainModel/Author/AuthorsWithMoreThanAThousandOfFollowers.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Cheeper\Chapter9\DomainModel\Author;
+
+use Cheeper\AllChapters\DomainModel\Author\AuthorId;
+
+interface AuthorsWithMoreThanAThousandOfFollowers
+{
+    /** @return AuthorId[] */
+    public function __invoke(): array;
+}

src/Cheeper/Chapter9/Infrastructure/DomainModel/Author/EventSourcedAuthorRepository.php

@@ -40,7 +40,7 @@ public function ofUserName(UserName $userName): ?Author
     }
     */
 
-    public function add(Author $author): void
+    public function save(Author $author): void
     {
         $this->eventStore->append(
             new EventStream(

src/Cheeper/Chapter9/Infrastructure/DomainModel/Author/TextFileAuthorsWithMoreThanAThousandOfFollowers.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Cheeper\Chapter9\Infrastructure\DomainModel\Author;
+
+use Cheeper\AllChapters\DomainModel\Author\AuthorId;
+use Cheeper\Chapter9\DomainModel\Author\AuthorsWithMoreThanAThousandOfFollowers;
+
+final readonly class TextFileAuthorsWithMoreThanAThousandOfFollowers implements AuthorsWithMoreThanAThousandOfFollowers
+{
+    public function __construct(
+        private string $filePath
+    ) {
+    }
+
+    public function __invoke(): array
+    {
+        return array_map(
+            fn(string $authorId) => AuthorId::fromString($authorId),
+            file($this->filePath)
+        );
+    }
+}