frontend/backend update

app/Invoice.php

@@ -6,12 +6,21 @@ use Illuminate\Database\Eloquent\Model;
 
 class Invoice extends Model
 {
+    protected $guarded = [
+        'id'
+    ];
+
     protected $casts = [
         'seller' => 'array',
         'client' => 'array',
         'bag'    => 'array',
     ];
 
+    /**
+     * Get user instance
+     *
+     * @return \Illuminate\Database\Eloquent\Relations\HasOne
+     */
     public function user() {
         return $this->hasOne(User::class, 'id', 'user_id');
     }