Fix HasManyThrough relationships (#416)

Author: driesvints

src/SearchableScope.php

@@ -4,6 +4,7 @@
 
 use Illuminate\Database\Eloquent\Builder as EloquentBuilder;
 use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\HasManyThrough;
 use Illuminate\Database\Eloquent\Scope;
 use Laravel\Scout\Events\ModelsFlushed;
 use Laravel\Scout\Events\ModelsImported;
@@ -45,5 +46,21 @@ public function extend(EloquentBuilder $builder)
                 event(new ModelsFlushed($models));
             });
         });
+
+        HasManyThrough::macro('searchable', function ($chunk = null) {
+            $this->chunkById($chunk ?: config('scout.chunk.searchable', 500), function ($models) {
+                $models->filter->shouldBeSearchable()->searchable();
+
+                event(new ModelsImported($models));
+            });
+        });
+
+        HasManyThrough::macro('unsearchable', function ($chunk = null) {
+            $this->chunkById($chunk ?: config('scout.chunk.searchable', 500), function ($models) {
+                $models->filter->shouldBeSearchable()->searchable();
+
+                event(new ModelsImported($models));
+            });
+        });
     }
 }