title: Populate the cloud firestore document containing an array of document references
body: <p>I have a collection named campgrounds in which every document contains an array of document reference to the documents in the comments collections.
  It looks like this <a href="https://ibb.co/hDd0kWV" rel="nofollow noreferrer">Campground</a></p>
  
  <p>I'm trying to figure out a way to populate this comments array before sending it to my ejs template.</p>
  
  <p>My code looks like this</p>
  
  <pre><code>app.get("/campgrounds/:docId", function(req, res) {
      var docRef = firestore.collection("campgrounds").doc(req.params.docId);
  
      try {
          docRef.get().then(doc =&gt; {
              if (!doc.exists) {
                  res.send("no such document");
              } else {
                  // res.send(doc.data());
                  res.render("campground", {
                      doc: doc.data(),
                      title: doc.data().title,
                      id: req.params.docId
                  });
              }
          });
      } catch (error) {
          res.send(error);
      }
  });
  </code></pre>