Maybe, 
You can avoid create Card object to delete and give this task to db using ```Card.delete_all(["id in (?)", ids])``` instead.
Also if you are using ajax to do it, you can make more verbose the response adding the status, it depend of the Delete operation.
Ex:.
```rb
status =  Card.delete_all(["id in (?)", ids]) ? :ok : :not_found
render  nothing: true, status: status
```