[11.x] Add CollectedBy attribute

src/Illuminate/Database/Eloquent/Attributes/CollectedBy.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace Illuminate\Database\Eloquent\Attributes;
+
+use Attribute;
+
+#[Attribute(Attribute::TARGET_CLASS)]
+class CollectedBy
+{
+    /**
+     * Create a new attribute instance.
+     *
+     * @param  class-string<\Illuminate\Database\Eloquent\Collection<*, *>>  $collectionClass
+     * @return void
+     */
+    public function __construct(public string $collectionClass)
+    {
+    }
+}

src/Illuminate/Database/Eloquent/HasCollection.php

@@ -2,11 +2,19 @@
 
 namespace Illuminate\Database\Eloquent;
 
+use Illuminate\Database\Eloquent\Attributes\CollectedBy;
+use ReflectionClass;
+
 /**
  * @template TCollection of \Illuminate\Database\Eloquent\Collection
  */
 trait HasCollection
 {
+    /**
+     * @var array<class-string<static>, class-string<TCollection>>
+     */
+    protected static array $resolvedCollectionClasses = [];
+
     /**
      * Create a new Eloquent Collection instance.
      *
@@ -15,6 +23,25 @@ trait HasCollection
      */
     public function newCollection(array $models = [])
     {
-        return new static::$collectionClass($models);
+        static::$resolvedCollectionClasses[static::class] ??= $this->resolveCollectionAttribute() ?? static::$collectionClass;
+
+        return new static::$resolvedCollectionClasses[static::class]($models);
+    }
+
+    /**
+     * Resolve the collection class name from the CollectedBy attribute.
+     *
+     * @return class-string<TCollection>|null
+     */
+    public function resolveCollectionAttribute()
+    {
+        $reflectionClass = new ReflectionClass(static::class);
+        $attributes = $reflectionClass->getAttributes(CollectedBy::class);
+
+        if (! isset($attributes[0]) || ! isset($attributes[0]->getArguments()[0])) {
+            return;
+        }
+
+        return $attributes[0]->getArguments()[0];
     }
 }

tests/Database/DatabaseEloquentBelongsToManyWithCastedAttributesTest.php

@@ -62,6 +62,7 @@ protected function getRelation()
         $builder = m::mock(Builder::class);
         $related = m::mock(Model::class);
         $related->shouldReceive('newCollection')->passthru();
+        $related->shouldReceive('resolveCollectionAttribute')->passthru();
         $builder->shouldReceive('getModel')->andReturn($related);
         $related->shouldReceive('qualifyColumn');
         $builder->shouldReceive('join', 'where');

tests/Database/DatabaseEloquentModelTest.php

@@ -15,6 +15,7 @@
 use Illuminate\Database\Connection;
 use Illuminate\Database\ConnectionResolverInterface;
 use Illuminate\Database\ConnectionResolverInterface as Resolver;
+use Illuminate\Database\Eloquent\Attributes\CollectedBy;
 use Illuminate\Database\Eloquent\Attributes\ObservedBy;
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Casts\ArrayObject;
@@ -3169,6 +3170,14 @@ public function testGuardedWithMutators()
         $this->assertSame('123 Main Street', $model->address_line_one);
         $this->assertSame('Anytown', $model->address_line_two);
     }
+
+    public function testCollectedByAttribute()
+    {
+        $model = new EloquentModelWithCollectedByAttribute;
+        $collection = $model->newCollection([$model]);
+
+        $this->assertInstanceOf(CustomEloquentCollection::class, $collection);
+    }
 }
 
 class EloquentTestObserverStub
@@ -3928,3 +3937,12 @@ public function setFullAddressAttribute($fullAddress)
         $this->attributes['address_line_two'] = $addressLineTwo;
     }
 }
+
+#[CollectedBy(CustomEloquentCollection::class)]
+class EloquentModelWithCollectedByAttribute extends Model
+{
+}
+
+class CustomEloquentCollection extends Collection
+{
+}

types/Database/Eloquent/Model.php

@@ -2,14 +2,15 @@
 
 namespace Illuminate\Types\Model;
 
+use Illuminate\Database\Eloquent\Attributes\CollectedBy;
 use Illuminate\Database\Eloquent\Collection;
 use Illuminate\Database\Eloquent\HasCollection;
 use Illuminate\Database\Eloquent\Model;
 use User;
 
 use function PHPStan\Testing\assertType;
 
-function test(User $user, Post $post, Comment $comment): void
+function test(User $user, Post $post, Comment $comment, Article $article): void
 {
     assertType('UserFactory', User::factory(function ($attributes, $model) {
         assertType('array<string, mixed>', $attributes);
@@ -34,6 +35,7 @@ function test(User $user, Post $post, Comment $comment): void
 
     assertType('Illuminate\Database\Eloquent\Collection<(int|string), User>', $user->newCollection([new User()]));
     assertType('Illuminate\Types\Model\Posts<(int|string), Illuminate\Types\Model\Post>', $post->newCollection(['foo' => new Post()]));
+    assertType('Illuminate\Types\Model\Articles<(int|string), Illuminate\Types\Model\Article>', $article->newCollection([new Article()]));
     assertType('Illuminate\Types\Model\Comments', $comment->newCollection([new Comment()]));
 
     assertType('bool', $user->restore());
@@ -74,3 +76,19 @@ public function newCollection(array $models = []): Comments
 final class Comments extends Collection
 {
 }
+
+#[CollectedBy(Articles::class)]
+class Article extends Model
+{
+    /** @use HasCollection<Articles<array-key, static>> */
+    use HasCollection;
+}
+
+/**
+ * @template TKey of array-key
+ * @template TModel of Article
+ *
+ * @extends Collection<TKey, TModel> */
+class Articles extends Collection
+{
+}