类型错误：未定义不是函数 - Cloud Functions 中的 Promise.all() 错误

Question

I am trying to fetch the document ID's of all the users in my database. For which I have written this code:

exports.scheduledFunction = functions.pubsub
  .schedule('every 2 minutes')
  .onRun(async context => {
    console.log('This will be run every 2 minutes!');
    try {
      const usersRef = await admin //Works Perfectly, I get the QuerySnapshot of the collection
        .firestore()
        .collection('Users')
        .get();
      console.log('usersRef: ', usersRef);
      const userDocs = await Promise.all(usersRef); //This gives the error
      console.log('User Docs: ', userDocs);
    } catch (err) {
      console.log('err: ', err);
    }
    return null;
  });

I obtain this error on passing the QuerySnapshot promise in Promise.all() :

//Error
TypeError: undefined is not a function
    at Function.all (<anonymous>)
    at exports.scheduledFunction.functions.pubsub.schedule.onRun (/srv/index.js:624:38)
    at <anonymous>
    at process._tickDomainCallback (internal/process/next_tick.js:229:7)

I expected to collect all the document IDs from the result of Promise.all()

Help would be very much appreciated.

Answer 1

Promise.all() takes an array of promises. usersRef is neither an array, nor a promise. Since you're already awaited the promise returned by get(), that makes usersRef a QuerySnapshot object that's immediately available, so you will need to work with it on those terms. Since it's a snapshot and not a reference , you should probably name it differently. For example:

const usersSnapshot = await admin
        .firestore()
        .collection('Users')
        .get();

const usersDocs = usersSnapshot.docs
console.log(usersDocs)

usersSnapshot.forEach(doc => {
    console.log(doc)
})

Answer 2

The await Promise.all is not needed, since you already load all user documents int the first statement with get() and await .

So it should be:

  const usersDocs = await admin 
    .firestore()
    .collection('Users')
    .get();
  console.log('User Docs: ', userDocs);