firebase.auth().currentUser never works?

[Jason Sun]

  var user1;
  firebase.auth().onAuthStateChanged(function(user) {

    if (user) {
      user1 = user;
      console.log("user logged in");
      console.log("checkpoint");
      console.log(user.uid);   // this prints fine
     
      var num;
      firebase.database().ref('users/'+user.uid).once('value').then(function(snapshot){
        num= snapshot.numChildren();
        console.log(num);
      });


     console.log(user1.uid);

    }
    else{
      console.log("user not logged in");
    }
  });

console.log(user1.uid) // this goes to null, even when i put it in a while loop

var user = firebase.auth().currentUser //this goes to null always too

 

I can't seem to ever get firebase.auth().currentUser working. It always returns null. Any help?

[Dennis Jefferson]

Hey Jason,

Checking firebase.auth().currentUser during firebase initialization will return null. Try setting an observer...and checking the value of firebase.auth().currentUser after the observer is fired.

From the docs:

By using an observer, you ensure that the Auth object isn't in an intermediate state—such as initialization—when you get the current user.

firebase.auth().onAuthStateChanged(function(user) {
  if (user) {
    // User is signed in.
  } else {
    // No user is signed in.
  }
});

[Jason Sun]

Hey Dennis,

Thanks for the response. 

As I understand it, the observer will only be triggered when there is a change in the Auth state or after initialization. I've tried setting multiple observers but only the first one seems to run

Jason

[boj...@google.com]

A newly attached observer should trigger as soon as the initial state is resolved (null for logged out and the currentUser for logged in). It will then only trigger when there is an auth state change (new log in, log out, etc.).

Every time you attach a new observer, it will follow the same behavior, trigger first on initial state resolution and then anytime the auth state changes.

[Thadeu Luz]

Is there a way to get a promise that resolves when auth is initialized? Or something like "once" for onAuthStateChanged()?

[boj...@google.com]

You can unsubscribe your observer after the first call:

var observer = function(user) {

  // First call, do your thing.

  unsubscribe();

};

var unsubscribe = auth.onAuthStateChanged(observer);

You can also package the above logic in a promise. Something like this:

var p = new Promise(function(resolve, reject) {

  var observer = function(user) {

    // Unsubscribe on first call.

    unsubscribe();

    // Resolve with current state.

    resolve(user);

  };

  var unsubscribe = auth.onAuthStateChanged(observer);

});

[Thadeu Luz]

Great. Thanks.