通过Cloud Function中的时间戳从Cloud Firestore查询

Question

I write a script which removes events from Cloud Firestore by timestamp . A script run by a link in Cloud Function .

'use strict';
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();
var db;
var count = 0;

exports.removeOldEvents = functions.https.onRequest(async(req, res) => {
     db = admin.firestore();
     db.collection("Events")
     .where("timeStamp", "<", new Date())
     .get().then(function(querySnapshot) {
          count = querySnapshot.size;
          querySnapshot.forEach(function(doc) {
               db.collection("Events").doc(doc.id).delete();
               if (--count == 0) {
                    console.log("Successful ");
                    res.send("Successful ");
                    res.end();
               }
          });
     }).catch(function(error) {
          console.log("Error ", error);
          res.send("Error ", error);
     });

 });

What I need to write together:

new Date()

in order to remove old events by timeStamp?

Thanks!!!

Answer 1

You are calling in parallel several asynchronous tasks (ie through the delete() method) and you should send back the response only when all these tasks are completed.

Since the delete() method returns a Promise, you need to use Promise.all() , as follows:

....
exports.removeOldEvents = functions.https.onRequest((req, res) => {
  db = admin.firestore();
  db.collection('Events')
    .where('timeStamp', '<', new Date())
    .get()
    .then(querySnapshot => {
      var promises = [];
      querySnapshot.forEach(doc => {
        promises.push(
          db
            .collection('Events')
            .doc(doc.id)
            .delete()
        );
      });
      return Promise.all(promises);
    })
    .then(() => {
      console.log('Successful');
      res.send('Successful');
    })
    .catch(error => {
      console.log('Error ', error);
      res.status(500).send('Error ', error);
    });
});

Note that when you will call this HTTPS Cloud Function the value of new Date().getTime() will be now. So I make the assumption that you have some documents with a timeStamp value that is in the future, or you will most likely delete the entire collection!

---

Also note that if you are sure your query will return less than 500 document, you could use a batched write .