Read db data in Cloud Functions in Firebase

Question

In firebase documentation I didn't find a simple way to get data from firebase db - only by events (.on, .once). Is this the only way?

In this case, to get data from different branches, I need to describe handler in handler? And response.send() must be in deepest handler?

Is this the correct function?

exports.test = functions.https.onRequest((request, response) => {
var db = admin.database();

db.ref("test/val").once("value", snap => {
    var val1 = snap.val();
    db.ref("test/val").set(val1+1);
    db.ref("test2/val").once("value", snap => {
        var val2 = snap.val();
        response.send(val1+", "+val2);
    });
});

//response.send("bad way");
});

Michael Bleigh · Accepted Answer · 2017-10-31 01:04:11Z

2

You're close, but you need to make sure you wait for all asynchronous work to complete (your set does not get waited on). I've reworked it a bit to use promises instead of callbacks to make the flow clear:

exports.test = functions.https.onRequest((request, response) => {
  var db = admin.database();

  var val1, val2;
  db.ref("test/val").once("value").then(snap => {
    val1 = snap.val();
    return db.ref("test/val").set(val1+1);
  }).then(() => {
    return db.ref("test2/val").once("value');
  }).then(snap => {
    val2 = snap.val();
    response.send(val1+", "+val2);
  }).catch(err => {
    console.log(err);
    response.send("error occurred");
  });
});

answered Oct 31, 2017 at 1:04

Michael Bleigh

26.4k2 gold badges83 silver badges86 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Read db data in Cloud Functions in Firebase

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related