Support Source in snaphots

[Lyokone]

What feature would you like to see?

Being able to specify the source when using addSnapshotListener.

As requested here firebase/flutterfire#10069

How would you use it?

fun addSnapshotListener(
    activity: Activity,
    metadataChanges: Any,
    listener: EventListener<DocumentSnapshot!>,
    source: Source,
): ListenerRegistration```

[argzdev]

Hi @Lyokone, thanks for requesting this feature. Our engineers will take a look into this when they have the time.

That said, I think that checking for local changes will be sufficient for the mentioned use case of the request.

val docRef = db.collection("cities").document("SF")
docRef.addSnapshotListener { snapshot, e ->
    if (e != null) {
        Log.w(TAG, "Listen failed.", e)
        return@addSnapshotListener
    }

    val source = if (snapshot != null && snapshot.metadata.hasPendingWrites())
        "Local"
    else
        "Server"

    if (snapshot != null && snapshot.exists()) {
        Log.d(TAG, "$source data: ${snapshot.data}")
    } else {
        Log.d(TAG, "$source data: null")
    }
}

[michalkubizna]

@argzdev In a real-world scenario, such as a popular comment section with hundreds of comments, this solution is not sufficient. This is because the listener would continuously update as the collection changes, resulting in unnecessary charges for the app when only the first 10 or 20 comments are needed.

[cherylEnkidu]

Hi,

Thank you for filling up the ticket! The team is not available for support during the holiday break and we will get back to you in the new year. Happy holiday!

[michalkubizna]

@cherylEnkidu Hi, is this feature planned?

[cherylEnkidu]

Hi,

Internal tracking ticket(b/169688224)

The feature is inside our backlog but unfortunately it won't get prioritize. Currently the snapshot logic is only available inside the backend. In order to support the cache version snapshot, we need to reimplement the whole logic in the SDKs, which is a great amount of work and we didn't receive enough demand to plan for this. I have add this github ticket to support the request, thank you for filling it up!

[michalkubizna]

Understood, thank you for the update.

[cherylEnkidu]

Hi,

This feature is been tracked internally, I will close this github ticket and reporter will be notified in the future when the feature got implemented.

[cherylEnkidu]

Hi,

The team decided to keep the ticket open until the feature is implemented or bug is fixed for external visibility.