Add [Query].[count()] to [FireStore] for [Android/IOS]

[baseemomar]

Add support for thecount()function in Query to retrieve the count of documents matching a query without fetching the entire data. This will return an AggregateQuery which can be executed using get(AggregateSource). This feature significantly reduces network usage and Firestore read costs, especially for large datasets.

[chris-hatton]

This is also the only functionality that's keeping my team from removing a direct KMP Cocoapods dependency on Firebase, which really slows down Kotlin builds. count() will be a welcome addition to the wrapping.

[chris-hatton]

Duplicate of #657

[anggrayudi]

Any updates on this issue?

[anggrayudi]

This has shipped. Query.count() (along with sum() and average()) was merged via #830 and is available in v2.5.0 on Maven Central:

val total: Long = firestore.collection("users").where { ... }.count()

Implementations are present for Android, Apple and JS.

Editing my earlier note for accuracy: the merged API differs in shape from the original request — it's a suspend fun count(): Long rather than an AggregateQuery you execute via get(AggregateSource) — but nothing is functionally missing. AggregateSource has exactly one constant, SERVER (checked against firebase-firestore 26.1.2), and the Apple/JS equivalents are likewise server-only, so there is no other source that could be passed.

This one looks closeable.

[nbransby]

There's an open PR for this: #785 by @Daeda88, which adds aggregate query support to Firestore — AggregateQuery, AggregateField.Count and Query.count() — across Android, Apple and JS, with tests.