title: Flutter Multiple Firestore Queries
body: <p>I am trying to make multiple queries to Firestore and merge the results into one stream like <a href="https://stackoverflow.com/questions/47552876/multiple-firestore-queries-single-promise-callback">here</a>. I tried using <code>StreamGroup.merge()</code> but it's only returning the results of one stream. I noticed that it does actually get data for all the streams but only returns one when everything completes. Here is what I did:</p>
  
  <pre><code>Stream getStream(){
      List&lt;Stream&gt; streams = [];     
  
      streams.add(Firestore.instance.collection(Constants.REQUESTS_NODE).
      where("municipality",isEqualTo: "City of Johannesburg Metropolitan").
      where("service_id",isEqualTo: 2).
      snapshots());
      streams.add(Firestore.instance.collection(Constants.REQUESTS_NODE).
      where("municipality",isEqualTo: "Lesedi Local").where("service_id",isEqualTo: 2).
      snapshots());    
  
      return StreamGroup.merge(streams);
  
    }
  </code></pre>
  
  <p>What am I missing and doing wrong? The reason I'm doing this is to compensate for Firestore's lack of <code>OR</code> operator.</p>