Problem
You want to manually log a user in from their ID.
Solution
Use the Auth::loginUsingId() method.
$user = Auth::loginUsingId($user_id);
if ( ! $user)
{
throw new Exception('Error logging in');
}
This will lookup the user from the $user_id, log them into the session, and return the user object. If null is returned, then you know the $user_id was invalid.
If you want the "remember me" cookie to be set, pass true as the second argument.
Auth::loginUsingId($user_id, true);
Discussion
This does basically the same thing as Auth::login().
In fact, after this method looks up the user it calls Auth::login(). See Manually Logging a User In for more details.
