[chores:fix] Fixed PKI API query count regression due to DRF 3.18

[dee077]

Checklist

• I have read the OpenWISP Contributing Guidelines and OpenWISP Anti AI Spam Policy.
• I have manually tested the changes proposed in this pull request.
• I have written new test cases for new code and/or updated existing tests for changes to existing code.
• I have updated the documentation.

Description of Changes

Two tests are currently failin in CI with an increased query count:

1. test_ca_put_api — 8 instead of 6
2. test_cert_put_api — 11 instead of 10

See: https://github.com/openwisp/openwisp-controller/actions/runs/37550871419/job/112565767578.

Reason

We have set the common_name field in the Ca and Cert models with a unique constraint on ("common_name", "organization"), so the uniqueness is already checked by the model and enforced by the database.

With the latest DRF 3.18 update in openwisp-utils, common_name is picked up by the serializer's UniqueTogetherValidator for ("common_name", "organization"), so it checks this uniqueness again. Every PUT now re-checks it at the serializer level on top of the model's own UniqueConstraint check, which costs 2 extra queries per request:

• one to fetch the related organization
• one SELECT to probe for an existing (common_name, organization) row

Introduced in DRF 3.18.2.

Solution

1. Declare common_name explicitly as a read-only field in
   CaDetailSerializer and CertDetailSerializer. It is not editable after
   creation anyway, and the value is already validated by the model, so the
   duplicate check and its 2 queries are avoided.

2. Alternatively, if we would rather not add a read-only field, we can simply
   bump the expected query counts in the two tests (6 → 8 and 10 → 11) and
   accept the 2 extra queries per request.

Let me know if the second one is better; I have gone ahead with the first.

How to verify

Make sure the virtualenv has DRF = 3.18.3 then remove the two common_name lines from openwisp_controller/pki/api/serializers.py and run tests

Both tests fail with the counts above; with the fix in place, the suite passes.

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Files:

• openwisp_controller/pki/api/serializers.py

🔇 Additional comments (2)

openwisp_controller/pki/api/serializers.py (2)

101-101: LGTM!

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185-185: LGTM!

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📝 Walkthrough

Walkthrough

CaDetailSerializer and CertDetailSerializer now explicitly declare common_name as read-only.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to 1b951

The CA and certificate detail API contracts are preserved; no actionable merge risk is evident.

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❌ Failed checks (1 error)

Check name	Status	Explanation	Resolution
Title check	❌ Error	The title accurately describes the PKI API query-count regression and its fix, but the prefix is invalid. The requirements allow one prefix such as [fix] or [chores], while the title uses the combined…	Replace [chores:fix] with a single approved prefix, preferably [fix], such as "[fix] Fixed PKI API query count regression due to DRF 3.18".

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Ui Changes, Regression Test, Docs	✅ Passed	The PR changes only two serializer declarations. It does not change an end-user UI, add a feature, or change documented behavior, so screenshots and documentation updates are not required. Existing PK…
Description check	✅ Passed	The description explains the regression, root cause, solution, affected tests, and verification steps. It does not include the required Reference to Existing Issue section or Screenshot section, and t…

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Explanation

The title accurately describes the PKI API query-count regression and its fix, but the prefix is invalid. The requirements allow one prefix such as [fix] or [chores], while the title uses the combined prefix [chores:fix].

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[openwisp-companion]

Proposed change log entry:

[fix] Fixed PKI API query count regression in CI #1503

Declared common_name explicitly as a read-only field in
CaDetailSerializer and CertDetailSerializer to prevent duplicate
uniqueness checks introduced by recent Django REST Framework updates.
This avoids the extra database queries during PUT requests and resolves
the CI query count failures.

Closes #1503