| name | schemars |
| description | Research findings on the schemars Rust crate for JSON Schema generation. Auto-loads when working with schemars, JsonSchema derive macro, json_schema! macro, schema_for!, SchemaSettings, SchemaGenerator, JSON Schema from Rust types, schemars attributes, schemars feature flags, or migrating from schemars 0.8 to 1.x. |
| user-invocable | false |
Research: schemars
See findings.md for the complete analysis.
Key Recommendation
Use schemars 1.x (currently 1.2.1 as of March 2026). The API is stable post the 1.0 release. Schema is now a newtype over serde_json::Value, and the json_schema!({}) macro replaces verbose struct construction. If coming from 0.8, the migration guide covers the breaking changes — mainly feature flag renames and removing the schemars::schema module.
Quick Reference
- Add to project:
schemars = { version = "1", features = ["chrono04", "uuid1"] } (feature flags use version suffixes now)
- Basic usage:
#[derive(JsonSchema)] on structs/enums; generate with schema_for!(MyType) or SchemaGenerator
- Custom schema inline:
json_schema!({ "type": "string", "format": "email" }) — mirrors serde_json::json!()
- OpenAPI 3.0 compat: Use
SchemaSettings::openapi3().into_generator() — handles nullable style automatically
- Use
schemars::generate not schemars::gen — gen is a reserved keyword in Rust 2024 edition
- Option null handling: Always emits
"null" type; use AddNullable transform or openapi3() preset for nullable: true style
- Serde attributes respected automatically:
#[serde(rename_all = "camelCase")], #[serde(tag = "type")], etc.
- Override with
#[schemars(...)]: title, description, example, inline, schema_with, extend("key" = val), transform
