Is is possible to know that onSnpashot connection couldn't be established because of no/bad internet connection? (WEB SDK) [duplicate] - firebase

Question

I want to check user's online status, in realtime database I used to check this with the help of onDisconnect(), but now I've shifted to firestore and can't find any similar method in that.

Answer 1

According to this onDisconnect:
The onDisconnect class is most commonly used to manage presence in applications where it is useful to detect how many clients are connected and when other clients disconnect.
To be able to use presence in firestore, you need to connect firestore with realtime firebase(no other way).
Please check this for more info:
https://firebase.google.com/docs/firestore/solutions/presence

Answer 2

NOTE: This solution is not especially efficient
Off the top of my head (read: I haven't thought through the caveats), you could do something like this:
const fiveMinutes = 300000 // five minutes, or whatever makes sense for your app
// "maintain connection"
setInterval(() => {
userPresenceDoc.set({ online: new Date().getTime() })
}, fiveMinutes)
then, on each client...
userPresenceDoc.onSnapshot(doc => {
const fiveMinutesAgo = new Date().getTime() - fiveMinutes
const isOnline = doc.data().online > fiveMinutesAgo
setUserPresence(isOnline)
})
You'd probably want the code checking for presence to use an interval a little more than the interval used by the code maintaining the connection to account for network lag, etc.
A NOTE ABOUT COST
So, obviously, there could be significant lag between when someone disconnects and when that disconnection is recognized by other clients. You can decrease that lag time by increasing the frequency of writes to Firestore, and thus increasing your costs. Running the numbers, I came out with the following costs for different intervals, assuming a single client connection running continuously for a month:
Interval Cost/User/Month
----------------------------
10m $0.007776
5m $0.015552
1m $0.07776
10s $0.46656
5s $0.93312
1s $4.6656
Going with an interval of one second is pretty pricy, at $46,656 a month for a system with 10,000 users who leave the app open all month long. An interval of 10 minutes with the same number of users would only cost $77.76 a month. A more reasonable interval of one minute, 10,000 users, and only four hours of app usage per day per user, rings in at $129.60 / month.

Answer 3

There is no equivalent. The Firestore SDK currently doesn't have presence management like the Realtime Database SDK.
Instead, you might want to use the Realtime Database onDisconnect() in conjunction with Cloud Functions to kick off some work when the client disconnects from RTDB. You would be assuming that that your app probably also lost its connection to Firestore at the same time.

Answer 4

Try this, but this method kind of hackish because we cannot use onDisconnected in firestore. As far as I know, realtime database use secure WebSocket technology, so thats why onDisconnected have on it
But you can use realtime database that can be implemented in cloud functions
to update the firestore data,
functions.database.ref('users/{userId}').onUpdate()
Somewhere in clientside:
firebase.database()
.ref('.info/connected')
.on('value', async (snap) => {
if (snap.val() === true) {
// Update the online status in RTDB
await firebase.database()
.ref(`users/${credentials.user.uid}/`)
.set({
online_status: true,
start_online: firebase.database.ServerValue.TIMESTAMP
});
// OnDisconnect
firebase.database()
.ref(`users/${credentials.user.uid}/`)
.onDisconnect()
.set({
online_status: false,
last_online: firebase.database.ServerValue.TIMESTAMP
});
}
});
in cloudfunctions (this will be trigger on update)
export const onUserOnlineStatusChanged = functions.database.ref('users/{userId}').onUpdate((event: functions.Change<functions.database.DataSnapshot>, context: functions.EventContext) => {
return event.after.ref.once('value')
.then((dataSnapshot) => dataSnapshot.val()) // Get the latest value from the Firebase Realtime database
.then((value: any) => {
// Update the value from RTDB to Firestore
console.log('value.online_status', value.online_status);
if (value.online_status == true) {
// Set the value to the firestore
admin.firestore()
.collection('users_info')
.doc(context.params.userId) // Get document by the userId / Or use .where
.set({
online_status: value.online_status,
updated_at: new Date
}, {
mergeFields: [
'online_status',
'updated_at'
]
});
// Add code if necessary (when the online_status is true)
} else if (value.online_status == false) {
// Set the value to the firestore
admin.firestore()
.collection('users_info')
.doc(context.params.userId) // Get document by the userId / Or use .where
.set({
online_status: value.online_status,
updated_at: new Date
}, {
mergeFields: [
'online_status',
'updated_at'
]
});
// Add code if necessary (when the online_status is false)
}
});
});
It would take about 1 or 2 seconds to update from cloud function to firestore

Answer 5

There is not a direct way to do this thing but this trick helped me achieve this disconnect listener.
window.addEventListener("beforeunload", async function (e) { e.preventDefault(); await firestoreRef.doc("doc-ref").update({ online: false }); });