3.3 - Refusing Orders When There Are No More Tickets

app/Ticket.php

@@ -6,5 +6,8 @@ use Illuminate\Database\Eloquent\Model;
 
 class Ticket extends Model
 {
-    //
+    public function scopeAvailable($query)
+    {
+        return $query->whereNull('order_id');
+    }
 }