Implements a destructuring compatability syntax for v1 style in v2 by inlined · Pull Request #1832 · firebase/firebase-functions

inlined · 2026-03-17T20:22:30Z

Description

V2 handlers that have a corresponding v1 handler will now be able to destructure the original event format.
This allows migration of function declarations without migration of business logic.

NOTE: You can do a YOLO migration with this if you rename your function "fooV2" so the CLI deletes your old one and creates your new one, but this is not a true hand-held migration. You may drop events in the interim. If you want to do a migration before tooling is supported you should do the following:

Create a new v2 function signature that destructures the old params. Use it to call your v1 function
Deploy. Wait a few minutes for any backlog in your v1 function to be processed
Delete the v1 function and make its body the v2 function
Deploy again

Code sample

Standalone feature

export const uppercase = onValueCreated("messages/{id}", ({snap, context}) => {
  myOldBusinessLogicThatExpectsAV1Payload(snap, context);
});

As a DIY migration tool

// Old
export const uppercase = functions.database.ref("/messages/{id}").onCreate((snap, context) => {
  // Does some thing with snap
});

// Intermediate:
export const uppercase = functions.database.ref("/messages/{id}").onCreate((snap, context) => {
  // Does some thing with snap
});

export const uppercaseV2 = onValueCreated("/messages/{id}", ({snap, context}) => {
  await uppercase.run(snap, context);
});

// Final:
export const uppercasev2 = onValueCreated("/messages/{id}", ({snap, context}) => {
  // original code from uppercase v1
});

gemini-code-assist · 2026-03-17T20:23:20Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the migration path for Firebase Cloud Functions v1 users transitioning to v2. By implementing a new addV1Compat utility, v2 event handlers can now access event data using the familiar v1 event format, including properties like context and event-specific payloads (e.g., snapshot, change, message). This compatibility layer allows developers to update function declarations to v2 without immediately rewriting their core business logic, thereby reducing migration friction and potential errors.

Highlights

V1 Compatibility Utility: Introduced a new, generic addV1Compat utility function that dynamically adds V1-style compatibility properties (like context and event-specific data) as lazy-evaluated getters to V2 CloudEvent objects. This function is idempotent, ensuring properties are added only once.
Provider Integration: Integrated the addV1Compat function across various Cloud Functions for Firebase V2 providers, including Realtime Database, Firestore, Pub/Sub, Remote Config, Scheduler, Cloud Storage, and Cloud Tasks. This enables v2 handlers to destructure event objects using familiar v1 event formats.
Type System Enhancements: Updated event handler signatures and introduced V1Compat types to provide strong type inference and ensure correct usage of the new V1-compatible properties in v2 functions.
Comprehensive Testing: Added extensive test cases for each affected provider to thoroughly verify the correct behavior and data mapping of the V1-compatible getters, ensuring a robust migration path.

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Changelog

spec/v2/compat.spec.ts
- Renamed patchV1Compat to addV1Compat in tests.
- Refactored tests to validate the new getter-based V1 compatibility mechanism.
- Removed tests for unsupported event types and malformed Pub/Sub events, as the new addV1Compat is generic.
spec/v2/providers/database.spec.ts
- Added a test suite to verify V1-compatible getters for Realtime Database onValueWritten events.
spec/v2/providers/firestore.spec.ts
- Added test suites to verify V1-compatible getters for Firestore onOperation and onChangedOperation events.
spec/v2/providers/pubsub.spec.ts
- Corrected MessagePublishedData instantiation in an existing test.
- Added a test to ensure backward compatibility for user tests passing POJOs without V1 getters.
- Added a test suite to verify V1-compatible getters for Pub/Sub onMessagePublished events.
spec/v2/providers/remoteConfig.spec.ts
- Updated handler argument types in existing tests from 1 as any to {}.
- Added a test suite to verify V1-compatible getters for Remote Config onConfigUpdated events.
spec/v2/providers/scheduler.spec.ts
- Added a test suite to verify V1-compatible context for Scheduler onSchedule events.
spec/v2/providers/storage.spec.ts
- Added a test suite to verify V1-compatible getters for Cloud Storage onObjectArchived events.
spec/v2/providers/tasks.spec.ts
- Added a test suite to verify V1-compatible context for Cloud Tasks onTaskDispatched requests.
src/common/providers/tasks.ts
- Added a context getter to the Request object for task dispatch handlers to provide V1 compatibility.
src/v2/compat.ts
- Renamed patchV1Compat to addV1Compat.
- Refactored the function to be a generic utility that adds V1 compatibility properties as lazy-evaluated getters to any CloudEvent object.
- Removed specific Pub/Sub compatibility logic and related types (V1Context, PubSubCloudEvent, V1PubSubMessage).
- Introduced V1Compat type for better type inference.
src/v2/index.ts
- Removed the export of PubSubCloudEvent.
src/v2/providers/database.ts
- Imported addV1Compat and V1Compat.
- Added overloads to onValueWritten, onValueCreated, onValueUpdated, onValueDeleted to include V1Compat types in handler signatures.
- Modified onChangedOperation and onOperation to use addV1Compat to inject V1-compatible context and change/snapshot getters.
src/v2/providers/firestore.ts
- Imported addV1Compat and V1Compat.
- Added overloads to onDocumentWritten, onDocumentCreated, onDocumentUpdated, onDocumentDeleted (and their WithAuthContext counterparts) to include V1Compat types.
- Modified onOperation and onChangedOperation to use addV1Compat to inject V1-compatible context and snapshot/change getters.
src/v2/providers/pubsub.ts
- Replaced patchV1Compat with addV1Compat and V1Compat.
- Added overloads to onMessagePublished to include V1Compat types.
- Modified the internal function to use addV1Compat to inject V1-compatible context and message getters.
src/v2/providers/remoteConfig.ts
- Imported addV1Compat and V1Compat.
- Added overloads to onConfigUpdated to include V1Compat types.
- Modified the internal function to use addV1Compat to inject V1-compatible context and version getters.
src/v2/providers/scheduler.ts
- Imported EventContext from v1/cloud-functions.
- Added overloads to onSchedule to include context: EventContext in handler signatures.
- Modified the internal function to define a context getter on the ScheduledEvent object.
src/v2/providers/storage.ts
- Imported addV1Compat and V1Compat.
- Added overloads to onObjectArchived, onObjectFinalized, onObjectDeleted, onObjectMetadataUpdated to include V1Compat types.
- Modified onOperation to use addV1Compat to inject V1-compatible context and object getters.
src/v2/providers/tasks.ts
- Imported TaskContext.
- Added overloads to onTaskDispatched to include context: TaskContext in handler signatures.

Activity

The pull request introduces a new compatibility feature for v1 to v2 Cloud Functions migration.
New test cases have been added across multiple providers to ensure the V1 compatibility works as expected.

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Code Review

This pull request introduces a significant and well-executed refactoring to implement a generic v1 compatibility layer for v2 functions, enabling easier migration. The core change is the new generic addV1Compat function, which replaces provider-specific patching logic. This greatly improves code structure and maintainability. The use of TypeScript overloads to support both v1 and v2 style handlers is a clever approach to maintain type safety for developers. The accompanying test changes are comprehensive and validate the new compatibility layer effectively. I have one minor suggestion to improve robustness in an edge case.

src/v2/providers/scheduler.ts

inlined · 2026-03-20T16:35:48Z

Broken into 7 PRs

inlined added 2 commits March 17, 2026 11:57

Checkpoint before prompt 3

8c0648f

Complete

99f3638

inlined requested a review from shettyvarun268 March 17, 2026 20:22

gemini-code-assist bot reviewed Mar 17, 2026

View reviewed changes

src/v2/providers/scheduler.ts Show resolved Hide resolved

Fail more gracefully in testing when data is missing

a77f2bf

inlined closed this Mar 20, 2026

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Implements a destructuring compatability syntax for v1 style in v2#1832

Implements a destructuring compatability syntax for v1 style in v2#1832
inlined wants to merge 3 commits intomasterfrom
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inlined commented Mar 17, 2026

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inlined commented Mar 17, 2026

Description

Code sample

Standalone feature

As a DIY migration tool

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Summary of Changes

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inlined commented Mar 20, 2026

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