Log In

Passport exposes a login() function on req (also aliased as logIn()) that can be used to establish a login session.

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

When the login operation completes, user will be assigned to req.user.

Note: passport.authenticate() middleware invokes req.login() automatically. This function is primarily used when users sign up, during which req.login() can be invoked to automatically log in the newly registered user.