Wsrtjtyk

In my Firestore database I store DocumentReferences to users so that I am always using up-to-date user data such as username, profile pictures, and auth tokens.

I am also implementing Cloud Functions to listen for database triggers so that I can send notifications to those specific users about activity related to their posts.

This is where I run into trouble, because I do not know how to use the stored reference object properly inside the Node.js function when I access it like all other database information.

The following is my function code:

exports.countNameChanges = functions.firestore

.document('posts/{postId}')

.onUpdate((change, context) => {

  // Retrieve the current and previous value

  const data = change.after.data();

  const previousData = change.before.data();

  var registrationToken = '';



  var notification = '';

  var postTitle = data.statement;

  var userRef = data.userRef; //This is my `DocumentReference` object



  if (data.interactionCount > previousData.interactionCount && data.postTypeId == 2131165321) notification = 'You recieved a new comment!';

  if (data.interactionCount > previousData.interactionCount && data.postTypeId == 2131165335) notification = 'You recieved a new vote!';

  if (data.likes > previousData.likes) notification = 'You have a new post like!' ;

  if (data.dislikes > previousData.dislikes) notification = 'You have a new post dislike!' ;



  admin.firestore()

        .doc(userRef) //This is my `DocumentReference` object

        .get()

        .then(doc => {

            registrationToken = doc.data().token;



            var payload = {

               data: {

                  title: postTitle,

                  body: notification

               },

               token: registrationToken

            };



            admin.messaging().send(payload)

            .then((response) => {

               console.log('Successfully sent message:', response);

               })

            .catch((error) => {

               console.log('Error sending message:', error);

               })

        });



   });



});

My Function Log

I would assume that the DocumentReference object would be easy to work with
inside a Cloud Function since the object is supported for direct storage into Firestore, but I can't figure it out.

If userRef is a DocumentReference type object, then just call get() on it directly. Don't pass it to doc(). You're only supposed to pass string type objects to doc().

userRef.get().then(...)