Firestore Loops with Promises

Question

I cannot figure out what is wrong with how I'm implementing promises inside loops in a Firebase function. I get this error when running this function as a Firebase Scheduled function: "TypeError: undefined is not a function" specifying line 202 in my index.js (below). The function is not running to completion (all of the .thens are not completing). I have two other concerns:

That I'm not using Promise.all correctly and not returning promises in the proper places.

I get this error in my Firebase logs: "Value for argument "documentPath" is not a valid resource path. Path must be a non-empty string." when trying to get the document within the path in section 2 of the code below. The path is correct and is indeed strings as I have verified by inspecting the reference object.

  checkForTweetsToDelete: function(db) {

    ///////
    // 1. Get first collction - streamers
    let streamersRef = db.collection('streamers');
    let streamersQuery = streamersRef.get()
      .then(streamersSnap => {

        var promises = [];

        ///////
        // 2. Get settings for each streamer - Here is where I get a "Value for argument "documentPath" is not a valid resource path. Path must be a non-empty string."
        streamersSnap.forEach(streamerDoc => {

          let tweetSettingsRef = db.collection('streamers').doc((streamerDoc.id.toString())).collection('TweetSettings').doc('Settings');
          let settingsDoc = tweetSettingsRef.get()
            .then(doc => {

                ///////
                // 3. Get all 'no' Tweets for this streamer
                let tweetsRef = db.collection('streamers').doc(doc.data().twitchId).collection('TwitterPosts');
                let tweetsQuery = tweetsRef.where('deleted', '==', 'no').get()
                  .then(tweetsSnap => {

                    var tweetPromises = [];

                    tweetsSnap.forEach(tweetDoc => {

                      /////////////
                      // 4. Delete Tweet
                      const client = new Twitter({
                        subdomain: "api", // "api" is the default (change for other subdomains)
                        version: "1.1", // version "1.1" is the default (change for other subdomains)
                        consumer_key: APP_KEY, // from Twitter.
                        consumer_secret: APP_SECRET, // from Twitter.
                        access_token_key: USER_TOKEN, // from your User (oauth_token)
                        access_token_secret: SECRET // from your User (oauth_token_secret)
                      });

                      const user = client.post('statuses/destroy', {
                        id: tweetDoc.id,
                        trim_user: 1
                      })
                      .then(twitterResponse => {

                        ///////
                        // 5. Write to DB that this has been deleted.
                        let tweetRef = tweetsRef.doc(tweetDoc.id.toString());
                        let updatedDoc = tweetRef.set({
                          deleted : 'yes'
                        }, {merge: true}).then(() => {
                          return;
                        });

                        return Promise.all([updatedDoc]);
                        // 5
                        ///////

                      });
                      // 4
                      /////////////

                      tweetPromises.push(user);

                    });

                    return Promise.all(tweetPromises);
                  });

                  return Promise.all([tweetsQuery]);
                  // 3
                  ///////

            });

            promises.push(settingsDoc);
        });

        return Promise.all(promises);
        // 2
        ///////
      });

    return Promise.all([streamersQuery]);
    // 1
    ///////
  }

And my index.js

exports.scheduledFunction = functions.pubsub.schedule('every 1 minutes').onRun((context) => {
            console.log('This will run every 1 minutes!');

            var scheduled = require('./scheduledFunctions');
            if (admin.apps.length === 0 ) { admin.initializeApp(functions.config().firebase); }
            var db = admin.firestore();

            //scheduled.checkForTweetsToDelete(db);
            //return scheduled.checkForTweetsToDelete(db);
            return Promise.all( scheduled.checkForTweetsToDelete(db) ).then(function() { // Line 202
                console.log('Finished all promises!');
            });
        });

I removed most of the logic inside the .thens as well as the catchs for readability.

EDIT:

This question was helpful in understanding how this all should work: Firebase (Angular) Promises with Loops in Loops and after studying it I think I'm doing it just as explained, but still unsuccessful.

Have you considered using async/await to flatten your code structure? Might also solve your problem, but the example is a bit difficult to understand rn — kevmo314, Apr 17 '20 at 16:49
After struggling with this for two days I'm considering it, yes. Basically I've got a .then, a for loop, a .then, a for loop. — Nick H, Apr 17 '20 at 17:11
Basically I've got a .then -> for loop -> .then -> for loop -> .then. The deepest for loop needs to finish its .then s before iterating to the next value in the parent for loop. — Nick H, Apr 17 '20 at 17:17
Can't see why you might be getting that particular error, however once it is solved, you will need to address ... return Promise.all( scheduled.checkForTweetsToDelete(db) ).then(...) ... in which `scheduled.checkForTweetsToDelete(db)` returns Promise, not Array, therefore `Promise.all()` is inappropriate. Instead, simplify to ... return scheduled.checkForTweetsToDelete(db).then(...); — Roamer-1888, Apr 17 '20 at 19:03
@Roamer-1888 I did that and it fixed that error. I also solved the other problem. Was due to incorrect path on my part. — Nick H, Apr 28 '20 at 20:41

score 0 · Answer 1 · answered Apr 28 '20 at 20:42

Turns out I was calling the incorrect path elsewhere in my code. I was getting a value from the database then using it to call another reference path but that value was undefined. After fixing that I was able to fix the other promise error by following Roamer-1888's advice.

Firestore Loops with Promises

1 Answers1