Passport js authenticate by url

I'm using Express JS and Passport JS for my app.

I want to give a new user the opportunity to automatically login, once, by a specific URL. I can get the user from the database with the information from the URL, so I have an User object (with id, email, hashed password etc.) but I don't know how I can use passport to authenticate the user and login.

I tried executing below function with the user object I got from the database:

req.login(user, function(err) {
  if (err) { return next(err); }
  return res.redirect('/users/' + req.user.username);
});

source: http://ift.tt/1bPQo4n

But that didn't work. Guess it's just because the user object contains the hashed password... Anyone who ever tried this before and can tell me how it works?