[5.8] Fix many to many sync results with custom pivot model

src/Illuminate/Database/Eloquent/Relations/Concerns/InteractsWithPivotTable.php

@@ -4,10 +4,16 @@
 
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Collection;
+use Illuminate\Database\Eloquent\Relations\Pivot;
 use Illuminate\Support\Collection as BaseCollection;
 
 trait InteractsWithPivotTable
 {
+    /**
+     * @var Collection
+     */
+    private $current;
+
     /**
      * Toggles a model (or models) from the parent.
      *
@@ -88,9 +94,7 @@ public function sync($ids, $detaching = true)
         // First we need to attach any of the associated models that are not currently
         // in this joining table. We'll spin through the given IDs, checking to see
         // if they exist in the array of current ones, and if not we will insert.
-        $current = $this->newPivotQuery()->pluck(
-            $this->relatedPivotKey
-        )->all();
+        $current = $this->getCurrent()->pluck($this->relatedPivotKey)->all();
 
         $detach = array_diff($current, array_keys(
             $records = $this->formatRecordsList($this->parseIds($ids))
@@ -213,7 +217,14 @@ public function updateExistingPivot($id, array $attributes, $touch = true)
      */
     protected function updateExistingPivotUsingCustomClass($id, array $attributes, $touch)
     {
-        $updated = $this->newPivot([
+        $updated = $this->getCurrent()
+                    ->where($this->foreignPivotKey, $this->parent->{$this->parentKey})
+                    ->where($this->relatedPivotKey, $this->parseId($id))
+                    ->first()
+                    ->fill($attributes)
+                    ->isDirty();
+
+        $this->newPivot([
             $this->foreignPivotKey => $this->parent->{$this->parentKey},
             $this->relatedPivotKey => $this->parseId($id),
         ], true)->fill($attributes)->save();
@@ -634,4 +645,18 @@ protected function getTypeSwapValue($type, $value)
                 return $value;
         }
     }
+
+    /**
+     * Get the existing records.
+     *
+     * @return \Illuminate\Support\Collection
+     */
+    protected function getCurrent()
+    {
+        return $this->current ?: $this->newPivotQuery()->get()->map(function ($record) {
+            $class = $this->using ? $this->using : Pivot::class;
+
+            return (new $class)->setRawAttributes((array) $record, true);
+        });
+    }
 }

tests/Integration/Database/EloquentBelongsToManyTest.php

@@ -154,6 +154,31 @@ public function test_custom_pivot_class()
         $this->assertEquals(2, PostTagPivot::first()->tag_id);
     }
 
+    public function test_custom_pivot_class_using_sync()
+    {
+        Carbon::setTestNow('2017-10-10 10:10:10');
+
+        $post = Post::create(['title' => Str::random()]);
+
+        $tag = TagWithCustomPivot::create(['name' => Str::random()]);
+
+        $results = $post->tagsWithCustomPivot()->sync([
+            $tag->id => ['flag' => 1],
+        ]);
+
+        $this->assertNotEmpty($results['attached']);
+
+        $results = $post->tagsWithCustomPivot()->sync([
+            $tag->id => ['flag' => 1],
+        ]);
+
+        $this->assertEmpty($results['updated']);
+
+        $results = $post->tagsWithCustomPivot()->sync([]);
+
+        $this->assertNotEmpty($results['detached']);
+    }
+
     public function test_attach_method()
     {
         $post = Post::create(['title' => Str::random()]);