The response is exactly the thing that returned by the result after its execution. Whatever result is configured to return the result as a response, whichever result type and result code is actually returned it's all depends on your action configuration.
The problem you have that returns a whole page as a result is because the INPUT
result is returned when the validation fails. You have to either remove the validation
interceptor from the stack or if it's a dispatcher
result type, update the location
attribute of the result config before the result is executed.