Generate JSON Schema documents from Rust code
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};
pub struct MyStruct {
pub myint: i32,
pub mybool: bool,
pub mynullableenum: Option
pub enum MyEnum {
StringNewType(String),
StructVariant { floats: Vec
fn main() { let schema = schemafor!(MyStruct); println!("{}", serdejson::tostringpretty(&schema).unwrap()); } ```
Click to see the output JSON schema...
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"
}
}
}
}
}
}
]
}
}
}
One of the main aims of this library is compatibility with Serde. Any generated schema should match how serde_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};
pub struct MyStruct {
#[serde(rename = "myNumber")]
pub myint: i32,
pub mybool: bool,
#[serde(default)]
pub mynullableenum: Option
pub enum MyEnum {
StringNewType(String),
StructVariant { floats: Vec
fn main() { let schema = schemafor!(MyStruct); println!("{}", serdejson::tostringpretty(&schema).unwrap()); } ```
Click to see the output JSON schema...
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"
}
}
}
}
]
}
}
}
#[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.
impl_json_schema - implements JsonSchema for Schemars types themselvesSchemars can implement JsonSchema on types from several popular crates, enabled via optional dependencies (dependency versions are shown in brackets):
- chrono (^0.4)
- indexmap (^1.2)
- either (^1.3)
- uuid (^0.8)
- smallvec (^1.0)
- arrayvec (^0.5)