Firebase Cloud Functions does not create document in a subcollection

user_10997988 0
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When I use Firebase Cloud Functions in my Flutter app to create a document inside a collection it works:

const functions = require('firebase-functions');
const admin = require('firebase-admin');
exports.onCreatePost = functions.firestore
    .document("/posts/{postId}")
    .onCreate(async (snap, context) => {
        const doc = snap.data()
        const creatorId = doc.creatorId
        admin.firestore().collection('feeds').doc(creatorId).set({ 
                  Id: creatorId, 
                  isRead: false, 
                  timestamp: admin.firestore.FieldValue.serverTimestamp(), 
            })
        });

But when I try to add the same document inside a subcollection in that document, it does not work:

const functions = require('firebase-functions');
const admin = require('firebase-admin'); 
exports.onCreatePost = functions.firestore
    .document("/posts/{postId}")
    .onCreate(async (snap, context) => {
        const doc = snap.data()
        const creatorId = doc.creatorId
        admin.firestore().collection('feeds').doc(creatorId).collection('feedItems').doc(context.params.postId).set({ 
                  Id: creatorId, 
                  isRead: false, 
                  timestamp: admin.firestore.FieldValue.serverTimestamp(), 
            })
        });

What am I doing wrong? I do see that the cloud function was completed successfully in the logs, but the docment is not created in my Cloud Firestore.enter image description here

google-cloud-functions firebase javascript
1 Answers

I would expect neither function to work reliably, because you aren't returning a promise that resolves after the asynchronous work is complete. If you don't return a promise, then Cloud Functions might terminate your function before it's done.

Minimally, you should return the promise returned by set().

return admin.firestore()
  .collection('feeds')
  .doc(creatorId)
  .collection('feedItems')
  .doc(context.params.postId)
  .set(...)

You should also check the Cloud Functions log for errors. Errors will not show up in your app since the code is running completely outside of it.

I suggest also reviewing the documentation on this.

user_8071260
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