function writingData()

in firestore/extend-with-functions/functions/index.js [106:134]

• 18 lines of code
• 3 McCabe index (conditional complexity)

function writingData() {
  // [START writing_data]
  // Listen for updates to any `user` document.
  exports.countNameChanges = functions.firestore
      .document('users/{userId}')
      .onUpdate((change, context) => {
        // Retrieve the current and previous value
        const data = change.after.data();
        const previousData = change.before.data();

        // We'll only update if the name has changed.
        // This is crucial to prevent infinite loops.
        if (data.name == previousData.name) {
          return null;
        }

        // Retrieve the current count of name changes
        let count = data.name_change_count;
        if (!count) {
          count = 0;
        }

        // Then return a promise of a set operation to update the count
        return change.after.ref.set({
          name_change_count: count + 1
        }, {merge: true});
      });
  // [END writing_data]
}