Guillermo Views Transaction

incrementViews.js

/**
 * Increases view count by one.
 * @param: db {FirebaseDatabase} - Firebase Database instance
 * @param: id {String} - id of post
 * @return: Promise<{committed: boolean, snapshot: nullable firebase.database.DataSnapshot}>
 * @docs: https://firebase.google.com/docs/reference/js/firebase.database.Reference#transaction
 */
const incrementViews = (db, id) => {
  const ref = db.ref('views').child(id)
  return ref.transaction(currentViews => {
    // if it has never been set it returns null
    if(currentViews === null) { currentViews = 0; }
    return currentViews + 1;
  });
};