valid/CHANGELOG.md

Changelog

All notable changes to this module will be documented in this file.

The format is based on Keep a Changelog, and this module adheres to Semantic Versioning.

0.9.0 - 2026-03-18

Added

• Validator interface with a single Struct(v any) error method for struct tag validation.
• New(opts ...Option) Validator constructor; returns an English-language validator by default.
• Option functional-option type for configuring a Validator at construction time.
• WithMessageProvider(mp MessageProvider) Option option to replace the built-in message provider.
• MessageProvider interface with Message(field, tag, param string) string; implement to supply custom or localised messages.
• DefaultMessages (MessageProvider): built-in English messages for required, email, min, max, and a generic fallback.
• SpanishMessages (MessageProvider): opt-in Spanish translations for the same tag set.
• Error behaviour: a failing struct field returns *xerrors.Err with code ErrInvalidInput; structured context keys "field" and "tag" are attached via WithContext. The raw playground.ValidationErrors is chained via WithError for callers that need all failures.
• Error behaviour: passing a non-struct value returns *xerrors.Err with code ErrInternal (wrapping playground.InvalidValidationError).
• Only the first failing field is surfaced per Struct call; the full error slice is preserved in the error chain.

Design Notes

• go-playground/validator/v10 is used as the backend but is entirely hidden behind the Validator interface; no playground types appear in the public API.
• MessageProvider decouples human-readable text from validation logic, enabling i18n without any changes to the core package.
• A single *playground.Validate instance is created per Validator (not per call) to amortise the cost of reflection-based type caching.