[13.x] Check the class before calling relationLoaded in loadMissingRelationshipChain

src/Illuminate/Database/Eloquent/Collection.php

@@ -260,8 +260,8 @@ public function loadMissingRelationshipChain(array $tuples)
 
         $this->filter(function ($model) use ($relation, $class) {
             return ! is_null($model) &&
-                ! $model->relationLoaded($relation) &&
-                $model::class === $class;
+                $model::class === $class &&
+                ! $model->relationLoaded($relation);
         })->load($relation);
 
         if (empty($tuples)) {

tests/Integration/Database/EloquentModelRelationAutoloadTest.php

@@ -7,6 +7,7 @@
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Pagination\LengthAwarePaginator;
 use Illuminate\Support\Facades\Schema;
 use Illuminate\Tests\Integration\Database\DatabaseTestCase;
 
@@ -126,6 +127,51 @@ public function testRelationAutoloadWithSerialization()
         DB::disableQueryLog();
     }
 
+    public function testRelationAutoloadChainLoadsModelsOfTheGivenClass()
+    {
+        $post = Post::create();
+        $comment = $post->comments()->create(['parent_id' => null]);
+        $comment->likes()->create();
+        $comment->likes()->create();
+
+        $posts = Post::get();
+
+        $posts->loadMissingRelationshipChain([
+            ['comments', Post::class],
+            ['likes', Comment::class],
+        ]);
+
+        $this->assertTrue($posts[0]->relationLoaded('comments'));
+        $this->assertTrue($posts[0]->comments[0]->relationLoaded('likes'));
+        $this->assertCount(2, $posts[0]->comments[0]->likes);
+    }
+
+    public function testRelationAutoloadChainSkipsNonModelRelationValues()
+    {
+        $post = Post::create();
+        $comment = $post->comments()->create(['parent_id' => null]);
+        $comment->likes()->create();
+
+        $posts = Post::get();
+
+        // A relation is not required to hold a model or a collection of models.
+        // Packages such as Lighthouse put a paginator there to represent a paginated relation.
+        foreach ($posts as $each) {
+            $each->setRelation('comments', new LengthAwarePaginator($each->comments()->get(), 1, 10));
+        }
+
+        $posts->loadMissingRelationshipChain([
+            ['comments', Post::class],
+            ['likes', Comment::class],
+        ]);
+
+        $paginator = $posts[0]->getRelation('comments');
+
+        // The paginator is left as it was found rather than being loaded into.
+        $this->assertInstanceOf(LengthAwarePaginator::class, $paginator);
+        $this->assertFalse($paginator->items()[0]->relationLoaded('likes'));
+    }
+
     public function testRelationAutoloadWithCircularRelations()
     {
         $post = Post::create();