[Firebase] Firebase Cloud Functions

// Listens for new messages added to /messages/:pushId/original and creates an
// uppercase version of the message to /messages/:pushId/uppercase
exports.makeUppercase = functions.database.ref('/messages/{pushId}/original')
    .onWrite(event => {
      // Grab the current value of what was written to the Realtime Database.
      const original = event.data.val();
      console.log('Uppercasing', event.params.pushId, original);
      const uppercase = original.toUpperCase();
      // You must return a Promise when performing asynchronous tasks inside a Functions such as
      // writing to the Firebase Realtime Database.
      // Setting an "uppercase" sibling in the Realtime Database returns a Promise.
      return event.data.ref.parent.child('uppercase').set(uppercase);
    });

// Take the text parameter passed to this HTTP endpoint and insert it into the
// Realtime Database under the path /messages/:pushId/original
exports.addMessage = functions.https.onRequest((req, res) => {
  // Grab the text parameter.
  const original = req.query.text;
  // Push the new message into the Realtime Database using the Firebase Admin SDK.
  admin.database().ref('/messages').push({original: original}).then(snapshot => {
    // Redirect with 303 SEE OTHER to the URL of the pushed object in the Firebase console.
    res.redirect(303, snapshot.ref);
  });
});