Share/Unify `Timestamp` between `google_cloud_firestore` and `cloud_firestore`

[mafreud]

Proposal: Share/Unify Timestamp between google_cloud_firestore and cloud_firestore

Problem

When building full-stack Dart applications (Flutter on the client, Dart VM/Firebase Functions on the server), sharing data models with Firestore timestamps is highly problematic.

• cloud_firestore (specifically cloud_firestore_platform_interface) and google_cloud_firestore (firebase-admin-dart) define their own incompatible Timestamp classes.
• Even though they have the same underlying structure (seconds and nanoseconds), Dart's static type system treats them as completely separate types.
• As a result, shared models cannot run simple type checks (like value is Timestamp) without introducing Flutter dependencies to the backend. Developers must rely on brittle workarounds like string-based runtime type checking (value.runtimeType.toString().contains('Timestamp')).

Proposed Solution

We highly recommend extracting basic, pure Dart Firestore types (such as Timestamp and GeoPoint) into a lightweight, neutral package (e.g., firebase_common_types) with no dependencies on Flutter or VM-specific APIs.

Both cloud_firestore and google_cloud_firestore should then depend on and re-export these shared types. This will enable clean, type-safe full-stack Dart development.

[demolaf]

Hi @mafreud , this does make a lot of sense. I will raise this with the team and keep this issue updated.

[mafreud]

@demolaf Thank you as always!

[ChreSyr]

I'm running into a similar issue with Timestamp.

My Flutter app uses cloud_firestore to fetch documents containing Timestamp values. These documents are then passed to models defined in a separate package that is shared between the app and my Firebase Functions.

That shared package cannot depend on cloud_firestore, since it is also used by the dart functions package, which doesn't support flutter packages. Instead, it depends on google_cloud_firestore and therefore expects google_cloud_firestore.Timestamp.

As a result, my TimestampConverter (defined in the shared models package) cannot recognize the Timestamp instances returned by cloud_firestore, even though cloud_firestore depends on google_cloud_firestore.

This makes me wonder: why doesn't cloud_firestore expose and use the Timestamp type from google_cloud_firestore directly?

I've run into similar, although less impactful, issues with duplicated definitions of GeoPoint and Filter.

@demolaf Is the team considering addressing this in the future? Shared model packages seem like a common use case now that Dart support for Firebase Functions is available.

[demolaf]

@ChreSyr Yes, this has been raised internally. I'll try to provide feedback once I have more details.