feat(Flag Dependency): Index flag references by emyller · Pull Request #8525 · Flagsmith/flagsmith

emyller · 2026-09-14T14:23:59Z

I have read the Contributing Guide.
~~I have added information to docs/ if required so people know about the feature.~~
I have filled in the "Changes" section below.
I have filled in the "How did you test this code" section below.

Changes

Closes #8412

This implements the support foundation for flag dependency in the Management API:

Flag references (prerequisite) are now indexed upon creating and updating segments.
Segments are now validated against flag circular dependency when updating rules or overrides (in both Feature Versioning v1 and v2 models).

How did you test this code?

A whole lotta tests included.

vercel · 2026-09-14T14:24:05Z

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coderabbitai · 2026-09-14T14:24:06Z

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📝 Walkthrough

Walkthrough

The change adds a Django dependencies application and persistent segment-to-feature references. It maps supported $.flags conditions and validates environment-scoped dependency paths for cycles. Segment writes, overrides, feature-segment creation, and deletion maintain references within transactions. Tests and observability documentation cover the new behaviour.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~45 minutes

Severity of issue fixed: Medium

Merge Risk: 🔵 Low · up to ed3de

Segment flag dependency indexing and cycle validation now run on every segment update, including metadata-only edits, which adds extra database work to those writes. Behaviour remains correct, so this can be merged with a follow-up to skip the dependency work when segment rules are unchanged.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

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Actionable comments posted: 2

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📒 Files selected for processing (15)

api/app/settings/common.py
api/features/dependencies/exceptions.py
api/features/dependencies/mappers.py
api/features/dependencies/services.py
api/features/dependencies/types.py
api/features/feature_segments/views.py
api/features/future/services.py
api/tests/integration/conftest.py
api/tests/integration/features/conftest.py
api/tests/integration/features/dependencies/test_segment_management.py
api/tests/integration/features/future/test_flag_endpoint.py
api/tests/types.py
api/tests/unit/features/dependencies/__init__.py
api/tests/unit/features/dependencies/test_mappers.py
docs/docs/deployment-self-hosting/observability/_events-catalogue.md

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coderabbitai

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⚠️ Outside diff range comments (2)

🟠 Major · Serialise dependency validation per environment. · services.py:106-170

api/features/dependencies/services.py:106-170
🗄️ Data Integrity & Integration | 🟠 Major | 🏗️ Heavy lift

Serialise dependency validation per environment. FeatureSegmentViewSet.perform_create writes the new FeatureSegment and then calls validate_segment_flag_dependencies inside transaction.atomic(). The validator reads get_overrides_in_effect() from segments.services without select_for_update.

In an environment with use_v2_feature_versioning=False, two requests can add these edges concurrently:

feature A overrides a segment that references feature B;

feature B overrides a segment that references feature A.

Each transaction can validate before the other transaction commits. Both validations then pass, and both FeatureSegment rows commit, leaving the cycle A → B → A. SegmentFlagReference has only foreign keys, and FeatureSegment uniqueness covers only identical rows. No database constraint enforces an acyclic graph.

Lock a common row for each affected environment in a stable order before the dependency graph query, and hold the lock through the surrounding transaction's commit. Alternatively, enforce the acyclic invariant at the database boundary.

🟠 Major · Defer dependency indexing from segment writes. · serializers.py:224-244

api/segments/serializers.py:224-244
🚀 Performance & Scalability | 🟠 Major | 🏗️ Heavy lift

Defer dependency indexing from segment writes.

SegmentViewSet uses SegmentSerializer for segment writes. The serializer calls index_segment_flag_references() inside transaction.atomic(). For indexed rules, this performs a feature lookup, reads and deletes existing SegmentFlagReference rows, bulk-inserts replacements, and emits dependency log events. Updates also run validate_segment_flag_dependencies(), which queries dependency edges synchronously.

This extends the segment-write transaction and adds database and logging work to the request path. Defer indexing, or redesign the write path to preserve validation and consistency without this synchronous work.

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api/features/dependencies/mappers.py
api/tests/integration/features/dependencies/test_segment_management.py

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khvn26

LGTM bar a couple questions around the circular dependency validation. Good job 👍

coderabbitai

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⚠️ Outside diff range comments (1)

🟠 Major · Reject cross-project segment overrides before dependency validation. · services.py:24-62

api/features/dependencies/services.py:24-62
🗄️ Data Integrity & Integration | 🟠 Major | ⚡ Quick win

Reject cross-project segment overrides before dependency validation.

FeatureSegmentCreateSerializer accepts independent feature, segment, and environment foreign keys. FeatureSegmentPermissions checks only the environment permission, and get_overrides_in_effect() returns a global queryset. A request can therefore attach a project B segment to a project A feature and environment.

SegmentFlagReference does not enforce matching projects. _get_dependency_edges() then joins its prerequisite feature names without a project filter. If the project B segment references a feature named F, validation can treat that reference as a dependency of project A's feature F and raise a false CircularDependencyError.

Require matching project IDs when creating FeatureSegment and SegmentFlagReference rows. Also scope dependency traversal to the environment's project as a defensive check.

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api/features/dependencies/services.py
api/tests/unit/features/dependencies/test_services.py
docs/docs/deployment-self-hosting/observability/_events-catalogue.md

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Actionable comments posted: 1

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📒 Files selected for processing (25)

api/app/settings/common.py
api/features/dependencies/__init__.py
api/features/dependencies/apps.py
api/features/dependencies/exceptions.py
api/features/dependencies/mappers.py
api/features/dependencies/migrations/0001_initial.py
api/features/dependencies/migrations/__init__.py
api/features/dependencies/models.py
api/features/dependencies/services.py
api/features/dependencies/types.py
api/features/feature_segments/views.py
api/features/future/services.py
api/features/views.py
api/segments/serializers.py
api/segments/services.py
api/tests/integration/conftest.py
api/tests/integration/features/conftest.py
api/tests/integration/features/dependencies/test_segment_management.py
api/tests/integration/features/future/test_flag_endpoint.py
api/tests/types.py
api/tests/unit/features/dependencies/__init__.py
api/tests/unit/features/dependencies/test_mappers.py
api/tests/unit/features/dependencies/test_services.py
api/tests/unit/segments/test_unit_segments_services.py
docs/docs/deployment-self-hosting/observability/_events-catalogue.md

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api/features/dependencies/init.py
api/features/dependencies/migrations/init.py
api/tests/unit/features/dependencies/init.py

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…cy-flag-reference

khvn26

LGTM

emyller self-assigned this Sep 14, 2026

github-actions Bot added api Issue related to the REST API feature New feature or request labels Sep 14, 2026

emyller force-pushed the feat/segment-dependency-flag-reference branch from 36dde6b to b28b065 Compare September 15, 2026 12:12

github-actions Bot added feature New feature or request and removed feature New feature or request labels Sep 15, 2026

maybe the chicken came first

a819d0c

emyller force-pushed the feat/segment-dependency-flag-reference branch from b28b065 to a819d0c Compare September 15, 2026 14:00

github-actions Bot added feature New feature or request and removed feature New feature or request labels Sep 15, 2026

emyller added 2 commits September 15, 2026 18:04

index prerequisites

ec3f473

you can't depend on the unknown

d61176b

github-actions Bot added feature New feature or request docs Documentation updates and removed feature New feature or request labels Sep 15, 2026

vercel Bot had a problem deploying to Preview – docs September 15, 2026 21:27 Failure

emyller added 5 commits September 15, 2026 19:24

unindex

b37eac5

reindex

c402599

don't touch the hen

7d5c504

fix logging

c5ccaa2

or maybe the egg

3608b5e

emyller force-pushed the feat/segment-dependency-flag-reference branch from 66804ae to 3608b5e Compare September 16, 2026 00:20

vercel Bot had a problem deploying to Preview – docs September 16, 2026 00:21 Failure

github-actions Bot added feature New feature or request and removed feature New feature or request docs Documentation updates labels Sep 16, 2026

more queries!

640bffd

github-actions Bot added the docs Documentation updates label Sep 16, 2026

github-actions Bot added the feature New feature or request label Sep 17, 2026

coderabbitai Bot reviewed Sep 17, 2026

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Comment thread api/features/dependencies/mappers.py

Comment thread api/features/feature_segments/views.py

can't depend on a mystery

b25eecd

github-actions Bot added docs Documentation updates feature New feature or request and removed feature New feature or request docs Documentation updates labels Sep 17, 2026

coderabbitai Bot reviewed Sep 17, 2026

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khvn26 reviewed Sep 17, 2026

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Comment thread api/features/dependencies/services.py Outdated

Comment thread api/features/dependencies/services.py Outdated

Comment thread api/features/dependencies/services.py

emyller mentioned this pull request Sep 18, 2026

fix(Segments): Improve and consolidate service for fetching overrides #8548

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github-actions Bot added docs Documentation updates feature New feature or request and removed feature New feature or request docs Documentation updates labels Sep 18, 2026

vercel Bot deployed to Preview – docs September 18, 2026 12:45 View deployment

coderabbitai Bot reviewed Sep 18, 2026

View reviewed changes

less hops

ed3decf

emyller force-pushed the feat/segment-dependency-flag-reference branch from 8d64135 to ed3decf Compare September 18, 2026 12:56

github-actions Bot added feature New feature or request and removed feature New feature or request docs Documentation updates labels Sep 18, 2026

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Comment thread api/segments/serializers.py

Merge remote-tracking branch 'github/main' into feat/segment-dependen…

0d6e3cb

…cy-flag-reference

github-actions Bot added the docs Documentation updates label Sep 18, 2026

emyller added 2 commits September 18, 2026 13:10

fix test coverage

f7b8ac7

short-circuit

22199e1

khvn26 approved these changes Sep 18, 2026

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flagsmith-engineering Bot mentioned this pull request Sep 18, 2026

chore(main): release 2.274.0 #8546

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feat(Flag Dependency): Index flag references - #8525

feat(Flag Dependency): Index flag references#8525
emyller merged 23 commits into
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