feat(api): add experimental feature flag update endpoints #6305

gagantrivedi · 2025-11-19T14:04:54Z

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Changes

Adds two new experimental endpoints under /api/experiments/:

update-flag-v1: Update single feature state (environment default or segment override)
update-flag-v2: Update multiple feature states in a single request (environment default + segment overrides)
Related issues: Create new experimental endpoint to update a single feature state for a given feature #6279 Create new experimental endpoints to update a given feature in an environment #6233

How did you test this code?

Unit tests

Adds two new experimental endpoints under /api/experiments/: - update-flag-v1: Update single feature state (environment default or segment override) - update-flag-v2: Update multiple feature states in a single request (environment default + segment overrides)

vercel · 2025-11-19T14:04:59Z

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codecov · 2025-11-26T11:23:12Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.05%. Comparing base (bebb47b) to head (3704c9c).
⚠️ Report is 36 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6305      +/-   ##
==========================================
+ Coverage   98.02%   98.05%   +0.03%     
==========================================
  Files        1280     1289       +9     
  Lines       45406    46147     +741     
==========================================
+ Hits        44508    45249     +741     
  Misses        898      898

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- Parameterize test_update_flag_by_name for all value types (integer, string, boolean) - Remove unsupported float type from serializer (model doesn't support it) - Add test_serializers.py with unit tests for edge cases - Add test for duplicate segment_id validation - Add tests for updating existing segment overrides with priority - Add unit tests for boolean string conversion and replica path - Refactor _update_flag_for_versioning_v2 to separate segment vs environment default cases for cleaner code and full coverage

Replace SDK endpoint calls with direct database verification using get_environment_flags_list. This keeps the tests as proper unit tests rather than integration tests. - Remove sdk_client and sdk_client_factory fixtures - Remove get_identity_feature_state_from_sdk helper function - Remove Identity, Condition, SegmentRule imports and usage - Simplify segment override tests to verify database state directly

api/features/versioning/versioning_service.py

…rides Creating a FeatureSegment with a priority value doesn't trigger reordering of existing segments. Use .to() after creation to properly reorder. Fixes both V1 and V2 endpoints.

api/features/feature_states/serializers.py

…helper

…ride Prevents cross-project segment references and provides clear error messages for non-existent segments.

emyller

The experiment looks solid, despite the complexity brought by the 2x2 grid experiment x versioning version. Few suggestions.

emyller · 2025-12-04T21:01:51Z

api/environments/identities/models.py


    def update_traits(
        self,
+        # TODO: this typing isn't true as it also supports regular dicts like {"trait_key": "foo", "trait_value": "bar"}


Can we have an issue to cover this?

I am not sure why it's part of this pr

here: #6371

api/features/feature_states/serializers.py

emyller · 2025-12-04T21:09:53Z

api/features/feature_states/serializers.py

+        if value_type == "integer":
+            try:
+                int(string_val)
+            except ValueError:
+                raise serializers.ValidationError(
+                    f"'{string_val}' is not a valid integer"
+                )
+        elif value_type == "boolean":
+            if string_val.lower() not in ("true", "false"):
+                raise serializers.ValidationError(
+                    f"'{string_val}' is not a valid boolean (use 'true' or 'false')"
+                )


Can we have this logic abstracted? It is repeated but raising distinct exceptions, e.g. ValueError there, and ValidationError here.

This is intentional defense in depth. The serializer validates at the API boundary and returns 400 with user-friendly errors. The model validates at the data layer to prevent corruption if set_value() is called directly (e.g.,
from management commands, tasks, or other code paths). Different layers appropriately raise different exceptions: ValidationError for API responses, ValueError for programmatic misuse.

emyller · 2025-12-04T22:48:19Z

api/tests/unit/features/feature_states/test_serializers.py

+    )
+    serializer.is_valid()
+
+    with pytest.raises(Exception) as exc_info:


Is it possible to narrow down this exception type?

emyller · 2025-12-04T22:49:14Z

api/tests/unit/features/feature_states/test_serializers.py

Missing Given/When/Then markers.

emyller · 2025-12-05T00:04:04Z

api/features/versioning/versioning_service.py

    )


+def update_flag(


These functions perform multiple database writes without @transaction.atomic. Can we wrap them?

We don't have any early exits or conditional paths here that could leave things in a bad state - it's just a straight line of create → update → save. If any step fails, it raises and stops.

Also, if something does fail midway, we'd actually want to know about it. A 500 surfacing is useful signal - silently rolling back could hide bugs we should be investigating.

Worth noting that FeatureState is one of our hottest tables, so holding transaction locks longer than needed would hurt concurrent traffic.

Happy to add one if there's a specific consistency case I'm missing though!

emyller · 2025-12-05T00:05:49Z

api/features/versioning/versioning_service.py

+
+    updated_segments = []
+    for override in change_set.segment_overrides:
+        segment_states = get_environment_flags_dict(


get_environment_flags_dict is called once per segment override. Can we batch this into a single query?

I'd prefer to do that once this API is out of the experimentation stage

emyller · 2025-12-05T00:06:56Z

api/features/versioning/versioning_service.py

+        feature_name=feature.name,
+        additional_filters=Q(feature_segment__isnull=True, identity_id__isnull=True),
+    )
+    assert len(env_default_states) == 1


assert provides no message when it fails. Can we raise an explicit exception instead?

We don't expect it to fail. The assert is only included to improve readability and document the code.

emyller · 2025-12-05T00:08:26Z

api/tests/unit/features/feature_states/test_unit_feature_states_views.py

Can we have a test for concurrent modifications? This is relevant since atomicity is not implemented yet (see other thread).

That’s a fair point regarding concurrency. However, I’m a bit hesitant to add a specific test for it right now. In my experience, tests requiring thread orchestration to hit precise race windows tend to be quite flaky and hard to maintain.

Also, looking at the logic, I’m not sure a test would give us much new signal. Since we aren't implementing strict locking:

V2: Relies on versioning (last publisher wins). V1: Defaults to 'last write wins.'

Essentially, the test would just confirm that the last request overwrites the previous one, which is the expected behavior rather than a defect we need to catch. What do you think?

api/features/versioning/versioning_service.py

api/features/feature_states/views.py

matthewelwell and others added 2 commits October 29, 2025 10:23

Initial PoC for new endpoint

4ea79aa

gagantrivedi changed the title ~~Feat/experimental flag update endpoints~~ feat(api): add experimental feature flag update endpoints Nov 19, 2025

github-actions bot added the api Issue related to the REST API label Nov 19, 2025

gagantrivedi and others added 2 commits November 19, 2025 19:42

Merge branch 'main' into feat/experimental-flag-update-endpoints

0bc2de2

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Update SegmentSerializer name

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misc

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return 403 if change request is enabled

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gagantrivedi force-pushed the feat/experimental-flag-update-endpoints branch from f280c7f to b987697 Compare November 28, 2025 13:29

gagantrivedi force-pushed the feat/experimental-flag-update-endpoints branch from e998a78 to 56443a0 Compare December 4, 2025 08:21

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api/features/versioning/versioning_service.py Show resolved Hide resolved

fix: use .to() for priority reordering when creating new segment over…

8d43e11

…rides Creating a FeatureSegment with a priority value doesn't trigger reordering of existing segments. Use .to() after creation to properly reorder. Fixes both V1 and V2 endpoints.

gagantrivedi force-pushed the feat/experimental-flag-update-endpoints branch from 56443a0 to 8d43e11 Compare December 4, 2025 11:31

github-actions bot added feature New feature or request and removed feature New feature or request labels Dec 4, 2025

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api/features/feature_states/serializers.py Show resolved Hide resolved

gagantrivedi added 2 commits December 4, 2025 17:15

cleanup: refactor versioning service to remove early returns and use …

ce92682

…helper

fix: validate segment belongs to project before creating segment over…

b8eeb6d

…ride Prevents cross-project segment references and provides clear error messages for non-existent segments.

github-actions bot added feature New feature or request and removed feature New feature or request labels Dec 4, 2025

khvn26 assigned emyller and matthewelwell Dec 4, 2025

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chore: review fixes

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gagantrivedi force-pushed the feat/experimental-flag-update-endpoints branch from 610dba4 to 2b78c5e Compare December 5, 2025 06:00

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chore: remove outdated TODO comment

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gagantrivedi requested a review from emyller December 5, 2025 07:24

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khvn26 self-assigned this Dec 8, 2025

khvn26 self-requested a review December 8, 2025 11:35

feat(api): add experimental feature flag update endpoints #6305

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