Sample of how to export data from your existing firebase realtime database to firestorm.

firebaseToFirestore

  var config = {
    apiKey: "xxxxxxxxx",
    authDomain: "xxxxxxx",
    databaseURL: "https://xxxxxxx.firebaseio.com",
    projectId: "xxxxxxx",
    storageBucket: "xxxxxx.appspot.com",
    messagingSenderId: "xxxxxxxxxx"
  };
  firebase.initializeApp(config);


  const db = firebase.firestore().app.database();

  var hotels = db.ref("hotels");
  
  cafes.on('child_added', function(data) {
   console.log(data.val());
   writeToFirestore(data.val());
 });
   
function writeToFirestore(obj){
  var db = firebase.firestore();
  db.collection("hotels").add(obj);
}