title: Strongloop/Loopback: How to login if multiple models extend built-in User model
body: <p>I've just started to develop with Strongloop framework and I've seen that you can extend basic built-in models, such as the User model. E.g.: a Patient model may extend User model. Therefore, basic user information and services will be automatic extended from User model and it will be possible to request for login, logout etc. through the Patient model (e.g.: Patient.login(credentials)). </p>
  
  <p>However, if I have multiple models that extend from User model (e.g.: Physicion, Admin and Patient), how to execute remote methods from the User model without knowing which one of the three models do I have to execute? For instance, if I have a Patient account, I can request Patient.login(credentials), and the Strongloop will make the login correctly. On the other hand, at the login page, I don't know if a Patient or a Physicion user has typed his/her credentials. So, I don't know which login method do I have to invoke: if Patient.login or Physicion.login. The remote method User.login does not work in my case. How to request for login without knowing the type of user beforehand?</p>