update

app/Models/SupplyDemand.php

@@ -9,6 +9,7 @@ use Illuminate\Support\Facades\Cache;
 class SupplyDemand extends SoftDeletesModel
 {
 
+    protected $appends = ['files'];
     protected $casts = ['file_ids' => 'json'];
 
     public function getFilesAttribute($value)