title: Cloud Functions retrieve List from Firebase Database
body: <p>I'm triggering a Cloud Function using Http Request.
  The issue is to retrieve the entire List of Objects I have, without an event to then loop through them.
  The List is under the <strong>account/userId</strong> Node.</p>
  
  <p>Here is what I use but I get nothing:</p>
  
  <pre><code>return admin.database().ref('/account/' + userId).once('value').then(function (snap) {
          let data = snap.val();
  }
  </code></pre>