auto-login user when reopening app in Backand

Question

I have a simple Backand and Ionic app where I want users to log in once and no more from that point on, just like the Facebook app for example. So once the user is logged in, I receive a token from Backand. From what I know, I assume I have to save that token in localStorage (which I'm doing, and works). But from that point on, I don't understand what I need to do to log the user back in when he revisits.

I have tried in my angular "run" method to look for an existing token in the localstorage, and if one exists, I paste it in my http headers. (the following function exists in the authentication service and is being called in the "run" method).

self.checkExistingUser = function() {
  if ($localStorage.user_token) {
    $http.defaults.headers.common.Authorization = $localStorage.user_token;
    Backand.user.getUserDetails()
        .then(function (response) {
            // Do stuff
        }
    console.log('Token found, logging in user');
  }
};

I assumed that the "getUserDetails()" call would interpret the Authorization header I had just added. But that's what I misunderstood; that's not how it works.

So my question is: how do I automatically log in the returning (existing) user with that token? I can't seem to find any function for that purpose in the Backand docs.

Thanks in advance!

Answer 1

Your comment made me find the answer to my question, Kornatzky.

The problem was that I had included my appName, anonymousToken and signUpToken into the initialization (BackandProvider.init). Removing the anonymousToken and adding useAnonymousTokenByDefault:false solved the problem.

getUserDetails now returns my currently logged-in user instead of a Guest object. Thanks for your help!

Answer 2

Using Backend Vanilla SDK, this code:

backand.user.getUserDetails(false)
  .then(res => {
    console.log(res.data);
  })
  .catch(err => {
    console.log(err);
  });

will get the user details if he is authenticated, or null if not. So you do not need to login the user again. The false makes sure that it checks it internally without contacting Backend. You should structure your app around it.