title: Firestore: Passing angularfire2 async data as Ionic 3 navParams not working
body: <pre><code>cities: Observable&lt;any&gt;;
  
  
  this.cities = this.fsProvider.collection('cities').map(cities =&gt; {
      return cities.map(city =&gt; {
        city.country = this.fsProvider.doc(`countries/${city.country_id}`);
        return city;
      });
  });
  </code></pre>
  
  <p><code>city</code> includes <code>country</code> info as <code>Observable</code> data. So if I pass <code>city</code> to another page as a <code>navParam</code>, just <code>this.navCtrl.push(AnotherPage, {city: city})</code>, I can't get country info on the <code>AnotherPage</code>.</p>
  
  <p>I just added the demo here: <a href="https://stackblitz.com/edit/ionic-firestore" rel="noreferrer">https://stackblitz.com/edit/ionic-firestore</a>.</p>
  
  <p>Any thoughts are welcome.</p>