title: Why is data retrieved from Firestore returning empty array when there are subcollections present?
body: <p>I am trying to retrieve data from my the my firestore database using angularfire2.
  This is what my current database looks like. I have a users collection that contains the userId doc which binds the userDetails and userPosts together. 
  <a href="https://i.stack.imgur.com/iSFfD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/iSFfD.png" alt="enter image description here"></a></p>
  
  <p>However when I query this collection, it returns an empty array in the console.</p>
  
  <p><a href="https://i.stack.imgur.com/nvRnF.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/nvRnF.png" alt="enter image description here"></a></p>
  
  <p>I am using a firebase function to retrieve the data. </p>
  
  <p>Firebase Function Index.ts </p>
  
  <pre><code>export const getFeed = functions.https.onCall(async (req,res) =&gt;{
    const docs = await admin.firestore().collection('users').get()
      return docs.docs.map(doc =&gt; {
      return {
          postID: doc.id,
          ...doc.data()
           }
       }) 
   })
  </code></pre>
  
  <p>TS File </p>
  
  <pre><code>  tabTwoFeedInit (){    
        const getFeed = this.aff.httpsCallable('getFeed')
        this.ajax = getFeed({}).subscribe(data=&gt; {
          console.log(data)
          this.posts =  data 
            })  
        }
  </code></pre>
  
  <p>How can I retrieve data from this firebase database successfully? </p>