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Validation Reference

This page is the mechanical reference for how to declare validations in Apistry contracts.

For the conceptual model (why validation exists, what boundary it protects, and what does not belong at the API layer), see Core Concepts → Validation Model.

Audience

  • Implementer: needs exact syntax and where validations are allowed

Where validations are declared

Validations are declared in the OpenAPI contract using contract extensions (commonly x-validations).

They may be attached at different schema levels depending on the validation:

  • property-level (single field)
  • object-level (cross-field constraints)
  • array-level (collection rules)

The runtime evaluates these validations before persistence.

Execution rules (guarantees)

  • Validations are declarative and draw from a finite catalog.
  • Validation evaluation is deterministic and side-effect free (except where explicitly documented for specific platform validations).
  • Validation failures map to HTTP 422.
  • Validators do not select HTTP status codes; error mapping is owned by the runtime.

Validation function catalog

The full list of built-in validation functions is documented under:

  • reference/validations/

Each validation page documents:

  • intent and scope
  • supported schema locations
  • parameters
  • examples
  • Contract extensions: reference/contract-extensions.md
  • Error mapping: reference/error-codes-and-status-mapping.md