title: firebase database.ref().once callback never called (javascript, ionic)
body: <p>I am developing a firebase app with the ionic framework using javascript. All of my database writing operations work but I can't read data no matter what I try.</p>
  
  <p>I have inside a function:</p>
  
  <pre><code>  setCompanyAndTitle(){
      let uid = firebase.auth().currentUser.uid;
      let userRef = this.database.ref('users/'+uid);
      userRef.once('value').then(function(user){
        alert("pls " + user.displayName);
      //NEVER CALLED  !!!!!!!!
      }).catch(function(error){
        var errorMessage = error.message;
        alert(errorMessage);
      //NEVER CALLED  !!!!!!!!!
      });
  
    }
  </code></pre>
  
  <p>My firebase is initialized like so:</p>
  
  <pre><code>firebase.initializeApp({
      apiKey: "xxxxxxxxxxxxxxxxxxxxxxx",
      authDomain: "xxxxxxxxxxx.firebaseapp.com",
      databaseURL: "xxxxxxxxxx.firebaseio.com",
      projectId: "xxxxxxxxx",
      storageBucket: "xxxxxxxxxx.appspot.com",
      messagingSenderId: "000000000"
    });
  </code></pre>
  
  <p>I cant get the once() function to make a callback no matter what I try.</p>