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/*! Generate JSON Schema documents from Rust code ## Basic Usage If you don't really care about the specifics, the easiest way to generate a JSON schema for your types is to `#[derive(JsonSchema)]` and use the `schema_for!` macro. All fields of the type must also implement `JsonSchema` - Schemars implements this for many standard library types. ```rust use schemars::{schema_for, JsonSchema}; #[derive(JsonSchema)] pub struct MyStruct { pub my_int: i32, pub my_bool: bool, pub my_nullable_enum: Option<MyEnum>, } #[derive(JsonSchema)] pub enum MyEnum { StringNewType(String), StructVariant { floats: Vec<f32> }, } fn main() { let schema = schema_for!(MyStruct); println!("{}", serde_json::to_string_pretty(&schema).unwrap()); } ``` <details> <summary>Click to see the output JSON schema...</summary> ```json { "$schema": "http://json-schema.org/draft-07/schema#", "title": "MyStruct", "type": "object", "required": [ "my_bool", "my_int" ], "properties": { "my_bool": { "type": "boolean" }, "my_int": { "type": "integer", "format": "int32" }, "my_nullable_enum": { "anyOf": [ { "$ref": "#/definitions/MyEnum" }, { "type": "null" } ] } }, "definitions": { "MyEnum": { "anyOf": [ { "type": "object", "required": [ "StringNewType" ], "properties": { "StringNewType": { "type": "string" } } }, { "type": "object", "required": [ "StructVariant" ], "properties": { "StructVariant": { "type": "object", "required": [ "floats" ], "properties": { "floats": { "type": "array", "items": { "type": "number", "format": "float" } } } } } } ] } } } ``` </details> ### Serde Compatibility One of the main aims of this library is compatibility with [Serde](https://github.com/serde-rs/serde). Any generated schema *should* match how [serde_json](https://github.com/serde-rs/json) would serialize/deserialize to/from JSON. To support this, Schemars will check for any `#[serde(...)]` attributes on types that derive `JsonSchema`, and adjust the generated schema accordingly. ```rust use schemars::{schema_for, JsonSchema}; use serde::{Deserialize, Serialize}; #[derive(Deserialize, Serialize, JsonSchema)] #[serde(rename_all = "camelCase")] pub struct MyStruct { #[serde(rename = "myNumber")] pub my_int: i32, pub my_bool: bool, #[serde(default)] pub my_nullable_enum: Option<MyEnum>, } #[derive(Deserialize, Serialize, JsonSchema)] #[serde(untagged)] pub enum MyEnum { StringNewType(String), StructVariant { floats: Vec<f32> }, } fn main() { let schema = schema_for!(MyStruct); println!("{}", serde_json::to_string_pretty(&schema).unwrap()); } ``` <details> <summary>Click to see the output JSON schema...</summary> ```json { "$schema": "http://json-schema.org/draft-07/schema#", "title": "MyStruct", "type": "object", "required": [ "myBool", "myNumber" ], "properties": { "myBool": { "type": "boolean" }, "myNullableEnum": { "default": null, "anyOf": [ { "$ref": "#/definitions/MyEnum" }, { "type": "null" } ] }, "myNumber": { "type": "integer", "format": "int32" } }, "definitions": { "MyEnum": { "anyOf": [ { "type": "string" }, { "type": "object", "required": [ "floats" ], "properties": { "floats": { "type": "array", "items": { "type": "number", "format": "float" } } } } ] } } } ``` </details> `#[serde(...)]` attributes can be overriden using `#[schemars(...)]` attributes, which behave identically (e.g. `#[schemars(rename_all = "camelCase")]`). You may find this useful if you want to change the generated schema without affecting Serde's behaviour, or if you're just not using Serde. ## Feature Flags - `impl_json_schema` - implements `JsonSchema` for Schemars types themselves ## Optional Dependencies Schemars can implement `JsonSchema` on types from several popular crates, enabled via optional dependencies (dependency versions are shown in brackets): - [`chrono`](https://crates.io/crates/chrono) (^0.4) - [`indexmap`](https://crates.io/crates/indexmap) (^1.2) - [`either`](https://crates.io/crates/either) (^1.3) - [`uuid`](https://crates.io/crates/uuid) (^0.8) - [`smallvec`](https://crates.io/crates/uuid) (^1.0) - [`arrayvec`](https://crates.io/crates/arrayvec) (^0.5) */ /// The map type used by schemars types. /// /// Currently a `BTreeMap`, but this may change a different implementation /// with a similar interface in a future version of schemars. pub type Map<K, V> = std::collections::BTreeMap<K, V>; /// The set type used by schemars types. /// /// Currently a `BTreeSet`, but this may change a different implementation /// with a similar interface in a future version of schemars. pub type Set<T> = std::collections::BTreeSet<T>; mod flatten; mod json_schema_impls; #[macro_use] mod macros; /// JSON Schema generator and settings. pub mod gen; /// JSON Schema types. pub mod schema; pub use schemars_derive::*; // Export serde_json so schemars_derive can use it #[doc(hidden)] pub use serde_json as _serde_json; use schema::{Schema, SchemaObject}; /// A type which can be described as a JSON Schema document. /// /// This is implemented for many Rust primitive and standard library types. /// /// This can also be automatically derived on most custom types with `#[derive(JsonSchema)]`. /// /// # Example /// ``` /// use schemars::{schema_for, JsonSchema}; /// /// #[derive(JsonSchema)] /// struct MyStruct { /// foo: i32, /// } /// /// let my_schema = schema_for!(MyStruct); /// ``` pub trait JsonSchema { /// Whether JSON Schemas generated for this type should be re-used where possible using the `$ref` keyword. /// /// For trivial types (such as primitives), this should return `false`. For more complex types, it should return `true`. /// For recursive types, this **must** return `true` to prevent infinite cycles when generating schemas. /// /// By default, this returns `true`. fn is_referenceable() -> bool { true } /// The name of the generated JSON Schema. /// /// This is used as the title for root schemas, and the key within the root's `definitions` property for subschemas. fn schema_name() -> String; /// Generates a JSON Schema for this type. /// /// If the returned schema depends on any [referenceable](JsonSchema::is_referenceable) schemas, then this method will /// add them to the [`SchemaGenerator`](gen::SchemaGenerator)'s schema definitions. /// /// This should not return a `$ref` schema. fn json_schema(gen: &mut gen::SchemaGenerator) -> Schema; /// Helper for generating schemas for flattened `Option` fields. /// /// This should not need to be called or implemented by code outside of `schemars`, /// and should not be considered part of the public API. #[doc(hidden)] fn json_schema_for_flatten(gen: &mut gen::SchemaGenerator) -> Schema { Self::json_schema(gen) } /// Helper for generating schemas for `Option` fields. /// /// This should not need to be called or implemented by code outside of `schemars`, /// and should not be considered part of the public API. #[doc(hidden)] fn add_schema_as_property( gen: &mut gen::SchemaGenerator, parent: &mut SchemaObject, name: String, metadata: Option<schema::Metadata>, required: bool, ) { let mut schema = gen.subschema_for::<Self>(); schema = gen.apply_metadata(schema, metadata); let object = parent.object(); if required { object.required.insert(name.clone()); } object.properties.insert(name, schema); } } #[cfg(test)] pub mod tests { use super::*; pub fn schema_object_for<T: JsonSchema>() -> schema::SchemaObject { schema_object(schema_for::<T>()) } pub fn custom_schema_object_for<T: JsonSchema>( settings: gen::SchemaSettings, ) -> schema::SchemaObject { schema_object(custom_schema_for::<T>(settings)) } pub fn schema_for<T: JsonSchema>() -> schema::Schema { custom_schema_for::<T>(Default::default()) } pub fn custom_schema_for<T: JsonSchema>(settings: gen::SchemaSettings) -> schema::Schema { T::json_schema(&mut gen::SchemaGenerator::new(settings)) } pub fn schema_object(schema: schema::Schema) -> schema::SchemaObject { match schema { schema::Schema::Object(o) => o, s => panic!("Schema was not an object: {:?}", s), } } }