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#![forbid(unsafe_code)]
/*!
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> },
}
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"
}
},
"additionalProperties": false
},
{
"type": "object",
"required": [
"StructVariant"
],
"properties": {
"StructVariant": {
"type": "object",
"required": [
"floats"
],
"properties": {
"floats": {
"type": "array",
"items": {
"type": "number",
"format": "float"
}
}
}
}
},
"additionalProperties": false
}
]
}
}
}
```
</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", deny_unknown_fields)]
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> },
}
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"
}
},
"additionalProperties": false,
"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.
### Schema from Example Value
If you want a schema for a type that can't/doesn't implement `JsonSchema`, but does implement `serde::Serialize`, then you can generate a JSON schema from a value of that type. However, this schema will generally be less precise than if the type implemented `JsonSchema` - particularly when it involves enums, since schemars will not make any assumptions about the structure of an enum based on a single variant.
```rust
use schemars::schema_for_value;
use serde::Serialize;
#[derive(Serialize)]
pub struct MyStruct {
pub my_int: i32,
pub my_bool: bool,
pub my_nullable_enum: Option<MyEnum>,
}
#[derive(Serialize)]
pub enum MyEnum {
StringNewType(String),
StructVariant { floats: Vec<f32> },
}
let schema = schema_for_value!(MyStruct {
my_int: 123,
my_bool: true,
my_nullable_enum: Some(MyEnum::StringNewType("foo".to_string()))
});
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",
"examples": [
{
"my_bool": true,
"my_int": 123,
"my_nullable_enum": {
"StringNewType": "foo"
}
}
],
"type": "object",
"properties": {
"my_bool": {
"type": "boolean"
},
"my_int": {
"type": "integer"
},
"my_nullable_enum": true
}
}
```
</details>
## Feature Flags
- `derive` (enabled by default) - provides `#[derive(JsonSchema)]` macro
- `impl_json_schema` - implements `JsonSchema` for Schemars types themselves
- `preserve_order` - keep the order of struct fields in `Schema` and `SchemaObject`
## 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/smallvec) (^1.0)
- [`arrayvec`](https://crates.io/crates/arrayvec) (^0.5)
- [`url`](https://crates.io/crates/url) (^2.0)
- [`bytes`](https://crates.io/crates/bytes) (^1.0)
- [`enumset`](https://crates.io/crates/enumset) (^1.0)
- [`rust_decimal`](https://crates.io/crates/rust_decimal) (^1.0)
- [`bigdecimal`](https://crates.io/crates/bigdecimal) (^0.3)
For example, to implement `JsonSchema` on types from `chrono`, enable it as a feature in the `schemars` dependency in your `Cargo.toml` like so:
```toml
[dependencies]
schemars = { version = "0.8", features = ["chrono"] }
```
*/
/// The map type used by schemars types.
///
/// Currently a `BTreeMap` or `IndexMap` can be used, but this may change to a different implementation
/// with a similar interface in a future version of schemars.
/// The `IndexMap` will be used when the `preserve_order` feature flag is set.
#[cfg(not(feature = "preserve_order"))]
pub type Map<K, V> = std::collections::BTreeMap<K, V>;
#[cfg(feature = "preserve_order")]
pub type Map<K, V> = indexmap::IndexMap<K, V>;
/// The set type used by schemars types.
///
/// Currently a `BTreeSet`, but this may change to a different implementation
/// with a similar interface in a future version of schemars.
pub type Set<T> = std::collections::BTreeSet<T>;
/// A view into a single entry in a map, which may either be vacant or occupied.
//
/// This is constructed from the `entry` method on `BTreeMap` or `IndexMap`,
/// depending on whether the `preserve_order` feature flag is set.
#[cfg(not(feature = "preserve_order"))]
pub type MapEntry<'a, K, V> = std::collections::btree_map::Entry<'a, K, V>;
#[cfg(feature = "preserve_order")]
pub type MapEntry<'a, K, V> = indexmap::map::Entry<'a, K, V>;
mod flatten;
mod json_schema_impls;
mod ser;
#[macro_use]
mod macros;
/// This module is only public for use by `schemars_derive`. It should not need to be used by code
/// outside of `schemars`, and should not be considered part of the public API.
#[doc(hidden)]
pub mod _private;
pub mod gen;
pub mod schema;
pub mod visit;
#[cfg(feature = "schemars_derive")]
extern crate schemars_derive;
#[cfg(feature = "schemars_derive")]
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;
/// 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;
// TODO document and bring into public API?
#[doc(hidden)]
fn _schemars_private_non_optional_json_schema(gen: &mut gen::SchemaGenerator) -> Schema {
Self::json_schema(gen)
}
// TODO document and bring into public API?
#[doc(hidden)]
fn _schemars_private_is_option() -> bool {
false
}
}
#[cfg(test)]
pub mod tests {
use super::*;
pub fn schema_object_for<T: JsonSchema>() -> schema::SchemaObject {
schema_object(schema_for::<T>())
}
pub fn schema_for<T: JsonSchema>() -> schema::Schema {
let mut gen = gen::SchemaGenerator::default();
T::json_schema(&mut gen)
}
pub fn schema_object(schema: schema::Schema) -> schema::SchemaObject {
match schema {
schema::Schema::Object(o) => o,
s => panic!("Schema was not an object: {:?}", s),
}
}
}