Checking valid connection first before using available session info

# Test Case
* folder **demo** using database `demo`
* folder **demo_old** using database `demo_old`
* create new user on **demo** url and login
* then go to **demo_old** url
* new user from `demo` database shown because both using the same `opt["user_session"]`

## Solution
when you plan to use this class in more one application, make sure to set different `opt["user_session"]` value, or

## Alternative
you can use this update, to check first into valid connection before using session