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api-platform-errors

Skill2 starsChanged 6 months agoMITView on GitHub

Design API Platform 4.3 error handling around RFC 7807 (`application/problem+json`, default in 4.x). Covers `exceptionToStatus` mapping at config / resource / operation level, the 4.3 `errors: [DomainException::class]` flag on operations (auto-documented in OpenAPI), `#[ErrorResource]` + `ProblemExceptionInterface` to turn domain exceptions into documented error resources, custom Error Provider via `#[AsAlias('api_platform.state.error_provider')]`, the HTTP status resolution order (`exceptionToStatus` → `HttpExceptionInterface` → `ProblemExceptionInterface` → defaults → 500), validation error provider (422 + `ConstraintViolationList`), input validation (`Assert\*` on the DTO Input or entity, `UniqueEntity`, validation groups via `validationContext`, custom `Constraint` + `ConstraintValidator`, `collectDenormalizationErrors`, `serialize_payload_fields` for debug, `ValidationException` 4.x namespace move), prod-safe error messages (`setDetail('An unexpected error occurred.')` for 500), stable error `type` URIs (versioned `/errors/v1/...`), and the safety rule of not leaking enumeration details in 401/403. Trigger on "model a domain exception", "RFC 7807", "Problem Detail", "exception to status", "404 vs 410 gone", "validation groups", "Assert constraint", "UniqueEntity", "422 ConstraintViolationList", or "hide error stack trace in prod".

The file

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  • Distinctive
  • Very specific
  1. Very specific:

    Add errors: [...] on relevant operations so OpenAPI documents the failure cases.

    line 25
  2. Very specific:

    Verify: 422 / 404 / 409 / 410 / 500 all round-trip with the correct Content-Type: application/problem+json.

    line 27

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

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Files
SKILL.md

API Platform 4.3 — Errors (RFC 7807, ErrorResource, custom Error Provider)

Use when

  • Designing a new domain exception and how it surfaces in the API.
  • Mapping exception → status code globally or per operation.
  • Hiding 500 stack traces in production while keeping meaningful 4xx errors.
  • Adding errors: [DomainException::class] so OpenAPI documents the failure case.
  • Customizing the error provider to enrich Problem Detail payloads (type, title, instance).

Default workflow

  1. Confirm rfc_7807_compliant_errors: true is set (default in 4.x — Problem Detail format).
  2. For each domain exception, decide: exceptionToStatus mapping, #[ErrorResource] (documented + customizable), or rely on the default.
  3. Add errors: [...] on relevant operations so OpenAPI documents the failure cases.
  4. Implement a custom Error Provider only when you need to enrich the Problem payload (setDetail, type, instance).
  5. Verify: 422 / 404 / 409 / 410 / 500 all round-trip with the correct Content-Type: application/problem+json.

Guardrails

  • No stack traces / file paths in production. A 500 always gets a generic detail.
  • No business details in 401 / 403. Enumeration risk — generic "Access denied".
  • Stable type URIs. Clients pattern-match on them — version them (/errors/v1/stock-unavailable).
  • ValidationException namespace: in 4.x it lives at ApiPlatform\Validator\Exception\ValidationException. The legacy ApiPlatform\Symfony\… path is removed.

Progressive disclosure

  • SKILL.md covers posture and rules.
  • reference.md carries the full config, exceptionToStatus levels, #[ErrorResource] template, custom Error Provider with Error::createFromException, status resolution order, validation error provider, prod-safe pattern, type versioning.

Output contract

  • Domain exceptions either mapped via exceptionToStatus or modeled as #[ErrorResource] with ProblemExceptionInterface.
  • Operations declaring errors: [...] for documented failure modes.
  • Tests asserting application/problem+json Content-Type and the exact type / title / status fields.
  • Production environment configured to hide stack traces.

References

  • reference.md

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