schemars/docs/4-features.md

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Feature Flags	5	/features/

Feature Flags and Optional Dependencies

• derive (enabled by default) - provides #[derive(JsonSchema)] macro
• preserve_order - keep the order of struct fields in Schema properties
• raw_value - implements JsonSchema for serde_json::value::RawValue (enables the serde_json raw_value feature)

Schemars can implement JsonSchema on types from several popular crates, enabled via feature flags (dependency versions are shown in brackets):

• arrayvec07 - arrayvec (^0.7)
• bigdecimal04 - bigdecimal (^0.4)
• bytes1 - bytes (^1.0)
• chrono04 - chrono (^0.4)
• either1 - either (^1.3)
• enumset1 - enumset (^1.0)
• indexmap2 - indexmap (^2.0)
• rust_decimal1 - rust_decimal (^1.0)
• semver1 - semver (^1.0.9)
• smallvec1 - smallvec (^1.0)
• smol_str02 - smol_str (^0.2.1)
• url2 - url (^2.0)
• uuid1 - uuid (^1.0)

For example, to implement JsonSchema on types from chrono, enable it as a feature in the schemars dependency in your Cargo.toml like so:

[dependencies]
schemars = { version = "1.0.0-alpha.2", features = ["chrono04"] }