Gate DEBUG output validation to serializer-derived viewsets#14811
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Legacy explicit-values viewsets often pair a write-oriented serializer_class with a different read shape, so validating their serialized output against the serializer raised spurious ValueErrors (500s) in dev mode. Track whether a class derives its values from its serializer and only build/apply the DEBUG validation schema when it does. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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marcellamaki
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this does fix the problem 🙂
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Summary
The DEBUG-mode output validator in
ValuesViewset.serialize()ran against every viewset. Legacy viewsets that pair an explicitvaluestuple with a write-orientedserializer_classwere validated against the wrong contract, so they 500ed in dev mode. Validation is now gated to viewsets whose values are derived from their serializer; legacy explicit-values viewsets skip it.References
Follow-up to #14327, which introduced the DEBUG-mode output validation.
Reviewer guidance
To reproduce: on develop, run the dev server and request any endpoint backed by a legacy viewset that defines both
valuesandserializer_class(e.g./api/lessons/lesson/) — it 500s with aValueErrorabout missing/unexpected fields. On this branch the same request succeeds.The existing drift tests in
TestDevModeSafeguardscover that serializer-derived viewsets are still validated.AI usage
Implemented with Claude Code: it diagnosed the root cause, wrote failing tests reproducing the dev-mode 500 before the fix, and applied the gate. I reviewed the full diff before pushing.
🤖 Generated with Claude Code