How to increment a record in Firebase?

Question

I have a Firebase record "searches: 0" for each user. On some event, I'd like to add 1 to what the current count is. I've gotten this far, but for some reason, it's not working:

du.fbAddSearchCount = function() {
    var usr = new Firebase(firebase_url + "/users/" + user_uid);

    usr.on("value", function(snapshot) {
        user = snapshot.val();

       var usersRef = ref.child("users");

       var fbUser = usersRef.child(user_uid);
       fbUser.update( {
           searches: user.searches + 1
       });
    }
}

Any help to get this working?

Thank you.

That would be the value that is currently in the user's "searches" record in fire base. For example, if it's 5, I'd like this script to update that to read 6. — user1661677, Jul 15 '15 at 08:38
So what is not working? Gotta give some more details. Does it update the record at all but not with the new number? — Chrillewoodz, Jul 15 '15 at 09:26
Seems relevant: http://stackoverflow.com/questions/31361993/how-to-count-child-elements-in-angularfire/31362510#31362510 — Frank van Puffelen, Jul 15 '15 at 13:12
What event is supposed to trigger the incrementing of searches count? — awei, Jul 21 '16 at 23:12

score 21 · Answer 1 · edited Jul 17 '17 at 01:43

21

You can use transaction

var databaseRef = firebase.database().ref('users').child(user_uid).child('searches');

databaseRef.transaction(function(searches) {
  if (searches) {
    searches = searches + 1;
  }
  return searches;
});

edited Jul 17 '17 at 01:43

phd

82,685
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answered Aug 08 '16 at 14:17

Sunday G Akinsete

802
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14

22

Your code will not work when `searches = 0`. You can instead do this: `return (searches || 0) + 1;` – david-ojeda Feb 01 '17 at 15:32

score 21 · Accepted Answer · answered May 14 '20 at 10:01

There's a new method ServerValue.increment()in firebase JavaScript SDK v7.14.0

It's better for performance and cheaper since no round trip is required.

See here

Added ServerValue.increment() to support atomic field value increments without transactions.

API Docs here

Usage example:

firebase.database()
    .ref('users')
    .child(user_uid)
    .child('searches')
    .set(firebase.database.ServerValue.increment(1))

Or you can decrement, just put -1 as function arg like so:

firebase.database()
    .ref('users')
    .child(user_uid)
    .child('searches')
    .set(firebase.database.ServerValue.increment(-1))

Great update Oleg. There is now indeed also an `increment` operation for the Realtime Database, which performs significantly better than using a transaction (see my test [here](https://stackoverflow.com/questions/61536203/how-quickly-can-you-atomically-increment-a-value-on-the-firebase-realtime-databa)). — Frank van Puffelen, May 25 '20 at 00:37

Mathias Gilson · Answer 3 · 2020-01-04T11:42:24.463

For the Realtime Database the use of transaction seems to be the best way to do it. See the answer from Sunday G Akinsete

From his answer and the related comments:

firebase
    .database()
    .ref('users')
    .child(user_uid)
    .child('searches')
    .transaction(function(searches) {
        return (searches || 0) + 1
    })

For the Firestore Database you can use the Firebase Sentinel values to increment/decrement a value that without having to fetch it first

Increment

firebase
    .firestore()
    .collection('users')
    .doc('some-user')
    .update({ 
         valueToIncrement: firebase.firestore.FieldValue.increment(1) 
    })

Decrement

firebase
    .firestore()
    .collection('users')
    .doc('some-user')
    .update({ 
        valueToDecrement: firebase.firestore.FieldValue.increment(-1) 
    })

Documentation Reference

Nice, but the original question seems to be using Realtime Database instead of Firestore. — ntcho, Jan 03 '20 at 10:02
Ah yes I didn't notice, I updated the answer to specify that's for Firestore only. Thank you ! — Mathias Gilson, Jan 04 '20 at 11:31

tonethar · Answer 4 · 2021-10-20T17:08:54.017

For the Realtime Database, using increment() works well for this - here's a client-side JS example that uses the newer ESM syntax

import { getDatabase, ref, set, increment } from  "https://www.gstatic.com/firebasejs/9.1.3/firebase-database.js";


// Initialize Firebase
const firebaseConfig = { ...};
const app = initializeApp(firebaseConfig);


const writeFavNameData = name => {
    const db = getDatabase();
    const favRef = ref(db, 'favorites/' + name);
    set(favRef, {
            name,
            likes: increment(1)
    });
};

writeFavNameData("Petunia"); // `likes` is initialized at 1
writeFavNameData("Petunia"); // `likes` is now 2

Thanks for showing the Firebase 9 syntax. I couldn't find any examples in the docs for how to use increment like this. — Partik, Feb 12 '22 at 05:49

score 0 · Answer 5 · answered Sep 17 '17 at 03:09

0

ref.transection(function(queue_length) {
    if(queue_length|| (queue_length === 0))
    {
        queue_length++; 
    }
    return queue_length;

})

You can use like this ;)

answered Sep 17 '17 at 03:09

Sachin Kalonia

13
5

1

provide an explanation to your answer – Anantha Raju C Sep 17 '17 at 03:43
What environment COMPILES javascript? – Ivan Rubinson Apr 01 '19 at 20:25

score 0 · Answer 6 · answered Jan 17 '20 at 13:17

0

database.ref("users").child("user_uid").transaction((user) => {
    if (user) {
        user.searches = actives.searches + 1;
    }
    return user;
});

It works for you. I did that '.child('searches')' but It doesn't work.(nothing changed).

answered Jan 17 '20 at 13:17

Minwoo Yu

360
2
13

How to increment a record in Firebase?

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