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Fixed onDisconnect logic to use deviceId #1010

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2 changes: 1 addition & 1 deletion presence-firestore/README.md
Original file line number Diff line number Diff line change
Expand Up @@ -38,7 +38,7 @@ To deploy the sample to your Firebase app,
1. Run `npm install` to install dependencies for the server-side [functions](functions/) as detailed above.
2. From this top-level sample directory, deploy the `Realtime Database` trigger defined in [functions](functions/) to `Firebase Functions` and the [public](public/) directory app to `Firebase Hosting`.

Assumimg you've created a Firebase application called `firebase-example-123` (make sure it's upgraded to the Spark plan and that `Anonymous Authentication` are enabled).
Assumimg you've created a Firebase application called `firebase-example-123` (make sure it's upgraded to the Blaze plan and that `Anonymous Authentication` are enabled).

```sh
firebase use --add firebase-example-123
Expand Down
23 changes: 18 additions & 5 deletions presence-firestore/functions/index.js
Original file line number Diff line number Diff line change
Expand Up @@ -26,14 +26,18 @@ const firestore = admin.firestore();

// Create a new function which is triggered on changes to /status/{uid}
// Note: This is a Realtime Database trigger, *not* Firestore.
exports.onUserStatusChanged = functions.database.ref('/status/{uid}').onUpdate(
exports.onUserStatusChanged = functions.database.ref('/status/{uid}/devices/{deviceId}').onUpdate(
async (change, context) => {
// Get the data written to Realtime Database
const eventStatus = change.after.val();

const deviceKey = context.params.deviceId;

// Then use other event data to create a reference to the
// corresponding Firestore document.
const userStatusFirestoreRef = firestore.doc(`status/${context.params.uid}`);
const userFirestoreRef = firestore.doc(`status/${context.params.uid}`);
const userDeviceCollectionRef = userFirestoreRef.collection(`devices`);
const userStatusFirestoreRef = userDeviceCollectionRef.doc(deviceKey);

// It is likely that the Realtime Database change that triggered
// this event has already been overwritten by a fast change in
Expand All @@ -47,11 +51,20 @@ exports.onUserStatusChanged = functions.database.ref('/status/{uid}').onUpdate(
if (status.last_changed > eventStatus.last_changed) {
return null;
}

// Otherwise, we convert the last_changed field to a Date
eventStatus.last_changed = new Date(eventStatus.last_changed);

// ... and write it to Firestore.
return userStatusFirestoreRef.set(eventStatus);
if(status.state === 'offline') {
// ... and write it to Firestore.
await userStatusFirestoreRef.delete();

if ((await userDeviceCollectionRef.get()).empty) {
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async/await syntax targets ES2016+, which is inconsistent with the rest of the file. Looking for whether ES5 is the target, or ES2016+

return userFirestoreRef.delete();
}
} else {
await userFirestoreRef.set({ uid: context.params.uid });
return userStatusFirestoreRef.set(status.devices[deviceKey]);
}
return null;
});
// [END presence_sync_function]
50 changes: 28 additions & 22 deletions presence-firestore/public/index.js
Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,8 @@ function rtdb_presence() {

// Create a reference to this user's specific status node.
// This is where we will store data about being online/offline.
var userStatusDatabaseRef = firebase.database().ref('/status/' + uid);
// `push()` will add a new key to the user's path, acting as a deviceId
var deviceStatusDatabaseRef = firebase.database().ref('/status/' + uid + '/devices').push();
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sessions or connections is probably more accurate than devices, since the id isn't based on the device id.


// We'll create two constants which we will write to
// the Realtime database when this device is offline
Expand Down Expand Up @@ -49,25 +50,26 @@ function rtdb_presence() {
// method to add a set which will only trigger once this
// client has disconnected by closing the app,
// losing internet, or any other means.
userStatusDatabaseRef.onDisconnect().set(isOfflineForDatabase).then(function() {
deviceStatusDatabaseRef.onDisconnect().set(isOfflineForDatabase).then(function() {
// The promise returned from .onDisconnect().set() will
// resolve as soon as the server acknowledges the onDisconnect()
// request, NOT once we've actually disconnected:
// https://firebase.google.com/docs/reference/js/firebase.database.OnDisconnect

// We can now safely set ourselves as 'online' knowing that the
// server will mark us as offline once we lose connection.
userStatusDatabaseRef.set(isOnlineForDatabase);
deviceStatusDatabaseRef.set(isOnlineForDatabase);
});
});
// [END rtdb_presence]
}

function rtdb_and_local_fs_presence() {
async function rtdb_and_local_fs_presence() {
// [START rtdb_and_local_fs_presence]
// [START_EXCLUDE]
var uid = firebase.auth().currentUser.uid;
var userStatusDatabaseRef = firebase.database().ref('/status/' + uid);
var deviceStatusDatabaseRef = await firebase.database().ref('/status/' + uid + '/devices').push();
var deviceId = deviceStatusDatabaseRef.key;

var isOfflineForDatabase = {
state: 'offline',
Expand All @@ -80,34 +82,39 @@ function rtdb_and_local_fs_presence() {
};

// [END_EXCLUDE]
var userStatusFirestoreRef = firebase.firestore().doc('/status/' + uid);
var userFirestoreRef = firebase.firestore().collection('status').doc(uid);
await userFirestoreRef.set({ uid }); // In case the user's id document doesn't already exist.

var devicesCollectionRef = userFirestoreRef.collection('devices');
var deviceStatusFirestoreRef = devicesCollectionRef.doc(deviceId);


// Firestore uses a different server timestamp value, so we'll
// create two more constants for Firestore state.
var isOfflineForFirestore = {
state: 'offline',
last_changed: firebase.firestore.FieldValue.serverTimestamp(),
};

var isOnlineForFirestore = {
state: 'online',
last_changed: firebase.firestore.FieldValue.serverTimestamp(),
};

firebase.database().ref('.info/connected').on('value', function(snapshot) {
if (snapshot.val() == false) {
// Instead of simply returning, we'll also set Firestore's state
// to 'offline'. This ensures that our Firestore cache is aware
// of the switch to 'offline.'
userStatusFirestoreRef.set(isOfflineForFirestore);
firebase.database().ref('.info/connected').on('value', async function(snapshot) {
if (snapshot.val() === false) {
// Instead of simply returning, we'll also remove the device id from the user,
// and if no devices are left, we should delete the user as well.
// This ensures that our Firestore cache is aware that the device and/or user has been deleted
deviceStatusFirestoreRef.delete();
const deviceCollection = await devicesCollectionRef.get();
if(deviceCollection.empty) {
userFirestoreRef.delete();
}
return;
};

userStatusDatabaseRef.onDisconnect().set(isOfflineForDatabase).then(function() {
userStatusDatabaseRef.set(isOnlineForDatabase);
deviceStatusDatabaseRef.onDisconnect().set(isOfflineForDatabase).then(function() {
deviceStatusDatabaseRef.set(isOnlineForDatabase);

// We'll also add Firestore set here for when we come online.
userStatusFirestoreRef.set(isOnlineForFirestore);
userFirestoreRef.set({ uid });
deviceStatusFirestoreRef.set(isOnlineForFirestore);
});
});
// [END rtdb_and_local_fs_presence]
Expand All @@ -116,7 +123,7 @@ function rtdb_and_local_fs_presence() {
function fs_listen() {
// [START fs_onsnapshot]
userStatusFirestoreRef.onSnapshot(function(doc) {
var isOnline = doc.data().state == 'online';
var isOnline = !doc.empty;
// ... use isOnline
});
// [END fs_onsnapshot]
Expand All @@ -126,7 +133,6 @@ function fs_listen_online() {
var history = document.querySelector('#history');
// [START fs_onsnapshot_online]
firebase.firestore().collection('status')
.where('state', '==', 'online')
.onSnapshot(function(snapshot) {
snapshot.docChanges().forEach(function(change) {
if (change.type === 'added') {
Expand Down