public User IsUsernameValid(string username)
{
User user = null;
if ((user = _patientService.GetUserByUsername(username)) != null)
{
return(user);
}
else if ((user = _secretaryService.GetUserByUsername(username)) != null)
{
return(user);
}
else if ((user = _directorService.GetUserByUsername(username)) != null)
{
return(user);
}
else if ((user = _doctorService.GetUserByUsername(username)) != null)
{
return(user);
}
return(user);
}