title: Flutter: Shows some Firestore Collection with a StreamBuilder from an authenticated Firebase Auth User
body: <p>My app has a collection of cards and I need to add some car to the favorites list, and I would like that each user has its own favorites collection.</p>
  
  <p>So I did the classic StreamBuilder sample to show some list on Flutter:</p>
  
  <pre><code>StreamBuilder&lt;QuerySnapshot&gt;(
      stream: getCars()
  </code></pre>
  
  <p>If the getCars() function is like this, everything is ok:</p>
  
  <pre><code>getCars() {
     return Firestore.instance
      .collection("users")
      .document("oT646MvXXXXXXXXXXXjlN8L1V2")
      .collection("cars").snapshots();
  </code></pre>
  
  <p>}</p>
  
  <p>Let's say that "oT646MvXXXXXXXXXXXjlN8L1V2" is the FirebaseUser uid.</p>
  
  <p>But how can I read FirebaseUser uid dinamically to return the collection?</p>
  
  <p>I tried this code but it didn't work, since it returns a Future:</p>
  
  <p>getCarsError() async {
      FirebaseUser fUser = await FirebaseAuth.instance.currentUser();</p>
  
  <pre><code>return Firestore.instance
      .collection("users")
      .document(fUser.uid)
      .collection("cars").snapshots();
  </code></pre>
  
  <p>}</p>
  
  <p>How can I acompplish that?</p>
  
  <p>thank you</p>