rustschemas

Rustschemas is an open-source Rust crate that provides declarative schema generation and runtime validation for Rust data structures. It is designed to bridge Rust types and schema formats such as JSON Schema and OpenAPI by deriving schema information from Rust types and exposing it as a serializable schema representation. The project emphasizes compatibility with the Serde ecosystem and aims to enable type-safe API contracts and data validation across services.

Key features include broad type support, including primitive types, structs, enums, Option and Result wrappers, and common collections like Vec and HashMap. Users can attach constraints to fields, such as minimum or maximum values, string length, or patterns, via field attributes. The system supports nested and reusable schemas to avoid duplication and can accommodate custom validators or user-defined components. Generated schemas can describe both data structure and validation rules and can be emitted as JSON Schema or adapted for OpenAPI-compatible documents.

Usage typically involves annotating a type with derive(Schema) and optionally providing attributes to refine constraints. The library then exposes a function or mechanism to obtain the corresponding schema for a type, which can be serialized to JSON for documentation, validation, or API contract purposes. Rustschemas integrates with Serde mappings to align serialized data with the generated schema, facilitating validation during deserialization and ensuring consistency between code and documentation.

As an evolving, community-driven project, rustschemas focuses on extensibility, interoperability with existing Rust tooling, and clear, machine-readable schema output for contracts and validation workflows. See also JSON Schema, OpenAPI, Serde, and Rust.