# jsonschema
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[](https://crates.io/crates/jsonschema)
[](https://docs.rs/jsonschema/)
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A JSON Schema validator implementation. It compiles schema into a validation tree to have validation as fast as possible.
Supported drafts:
- Draft 7 (except optional `idn-hostname.json` test case)
- Draft 6
- Draft 4 (except optional `bignum.json` test case)
Partially supported drafts (some keywords are not implemented):
- Draft 2019-09 (requires the `draft201909` feature enabled)
- Draft 2020-12 (requires the `draft202012` feature enabled)
```toml
# Cargo.toml
jsonschema = "0.18"
```
To validate documents against some schema and get validation errors (if any):
```rust
use jsonschema::JSONSchema;
use serde_json::json;
fn main() {
let schema = json!({"maxLength": 5});
let instance = json!("foo");
let compiled = JSONSchema::compile(&schema)
.expect("A valid schema");
let result = compiled.validate(&instance);
if let Err(errors) = result {
for error in errors {
println!("Validation error: {}", error);
println!(
"Instance path: {}", error.instance_path
);
}
}
}
```
Each error has an `instance_path` attribute that indicates the path to the erroneous part within the validated instance.
It could be transformed to JSON Pointer via `.to_string()` or to `Vec<String>` via `.into_vec()`.
If you only need to know whether document is valid or not (which is faster):
```rust
use jsonschema::is_valid;
use serde_json::json;
fn main() {
let schema = json!({"maxLength": 5});
let instance = json!("foo");
assert!(is_valid(&schema, &instance));
}
```
Or use a compiled schema (preferred):
```rust
use jsonschema::JSONSchema;
use serde_json::json;
fn main() {
let schema = json!({"maxLength": 5});
let instance = json!("foo");
// Draft is detected automatically
// with fallback to Draft7
let compiled = JSONSchema::compile(&schema)
.expect("A valid schema");
assert!(compiled.is_valid(&instance));
}
```
## Output styles
`jsonschema` supports `basic` & `flag` output styles from Draft 2019-09, so you can serialize the validation results with `serde`:
```rust
use jsonschema::{Output, BasicOutput, JSONSchema};
use serde_json::json;
fn main() {
let schema_json = json!({
"title": "string value",
"type": "string"
});
let instance = json!("some string");
let schema = JSONSchema::compile(&schema_json)
.expect("A valid schema");
let output: BasicOutput = schema.apply(&instance).basic();
let output_json = serde_json::to_value(output)
.expect("Failed to serialize output");
assert_eq!(
output_json,
json!({
"valid": true,
"annotations": [
{
"keywordLocation": "",
"instanceLocation": "",
"annotations": {
"title": "string value"
}
}
]
})
);
}
```
## Custom keywords
`jsonschema` allows you to implement custom validation logic by defining custom keywords.
To use your own keyword, you need to implement the `Keyword` trait and add it to the `JSONSchema` instance via the `with_keyword` method:
```rust
use jsonschema::{
paths::{JSONPointer, JsonPointerNode},
ErrorIterator, JSONSchema, Keyword, ValidationError,
};
use serde_json::{json, Map, Value};
use std::iter::once;
struct MyCustomValidator;
impl Keyword for MyCustomValidator {
fn validate<'instance>(
&self,
instance: &'instance Value,
instance_path: &JsonPointerNode,
) -> ErrorIterator<'instance> {
// ... validate instance ...
if !instance.is_object() {
let error = ValidationError::custom(
JSONPointer::default(),
instance_path.into(),
instance,
"Boom!",
);
Box::new(once(error))
} else {
Box::new(None.into_iter())
}
}
fn is_valid(&self, instance: &Value) -> bool {
// ... determine if instance is valid ...
true
}
}
// You can create a factory function, or use a closure to create new validator instances.
fn custom_validator_factory<'a>(
// Parent object where your keyword is defined
parent: &'a Map<String, Value>,
// Your keyword value
value: &'a Value,
// JSON Pointer to your keyword within the schema
path: JSONPointer,
) -> Result<Box<dyn Keyword>, ValidationError<'a>> {
// You may return validation error if the keyword is misused for some reason
Ok(Box::new(MyCustomValidator))
}
fn main() {
let schema = json!({"my-type": "my-schema"});
let instance = json!({"a": "b"});
let compiled = JSONSchema::options()
// Register your keyword via a factory function
.with_keyword("my-type", custom_validator_factory)
// Or use a closure
.with_keyword("my-type-with-closure", |_, _, _| Ok(Box::new(MyCustomValidator)))
.compile(&schema)
.expect("A valid schema");
assert!(compiled.is_valid(instance));
}
```
## Reference resolving and TLS
By default, `jsonschema` resolves HTTP references via `reqwest` without TLS support.
If you'd like to resolve HTTPS, you need to enable TLS support in `reqwest`:
```toml
reqwest = { version = "*", features = [ "rustls-tls" ] }
```
Otherwise, you might get validation errors like `invalid URL, scheme is not http`.
## Status
This library is functional and ready for use, but its API is still evolving to the 1.0 API.
## Bindings
- Python - See the `./bindings/python` directory
- Ruby - a [crate](https://github.com/driv3r/rusty_json_schema) by @driv3r
- NodeJS - a [package](https://github.com/ahungrynoob/jsonschema) by @ahungrynoob
## Running tests
The tests in [jsonschema/](jsonschema/) depend on the [JSON Schema Test Suite](https://github.com/json-schema-org/JSON-Schema-Test-Suite). Before calling `cargo test`, download the suite:
```bash
$ git submodule init
$ git submodule update
```
These commands clone the suite to [jsonschema/tests/suite/](jsonschema/tests/suite/).
Now, enter the `jsonschema` directory and run `cargo test`.
```bash
$ cd jsonschema
$ cargo test
```
## Performance
There is a comparison with other JSON Schema validators written in Rust - `jsonschema_valid==0.5.2`, `valico==4.0.0`, and `boon==0.5.0`.
Test machine i8700K (12 cores), 32GB RAM.
Input values and schemas:
- [Zuora](https://github.com/APIs-guru/openapi-directory/blob/master/APIs/zuora.com/2021-04-23/openapi.yaml) OpenAPI schema (`zuora.json`). Validated against [OpenAPI 3.0 JSON Schema](https://github.com/OAI/OpenAPI-Specification/blob/main/schemas/v3.0/schema.json) (`openapi.json`).
- [Kubernetes](https://raw.githubusercontent.com/APIs-guru/openapi-directory/master/APIs/kubernetes.io/v1.10.0/swagger.yaml) Swagger schema (`kubernetes.json`). Validated against [Swagger JSON Schema](https://github.com/OAI/OpenAPI-Specification/blob/main/schemas/v2.0/schema.json) (`swagger.json`).
- Canadian border in GeoJSON format (`canada.json`). Schema is taken from the [GeoJSON website](https://geojson.org/schema/FeatureCollection.json) (`geojson.json`).
- Concert data catalog (`citm_catalog.json`). Schema is inferred via [infers-jsonschema](https://github.com/Stranger6667/infers-jsonschema) & manually adjusted (`citm_catalog_schema.json`).
- `Fast` is taken from [fastjsonschema benchmarks](https://github.com/horejsek/python-fastjsonschema/blob/master/performance.py#L15) (`fast_schema.json`, `fast_valid.json` and `fast_invalid.json`).
| OpenAPI | 18 KB | 4.5 MB |
| Swagger | 25 KB | 3.0 MB |
| Canada | 4.8 KB | 2.1 MB |
| CITM catalog | 2.3 KB | 501 KB |
| Fast (valid) | 595 B | 55 B |
| Fast (invalid) | 595 B | 60 B |
Here is the average time for each contender to validate. Ratios are given against compiled `JSONSchema` using its `validate` method. The `is_valid` method is faster, but gives only a boolean return value:
| OpenAPI | - (1) | - (1) | 11.71 ms (**x3.34**) | 3.500 ms | 3.147 ms (**x0.89**) |
| Swagger | - (2) | 180.65 ms (**x32.12**) | 16.01 ms (**x2.84**) | 5.623 ms | 3.634 ms (**x0.64**) |
| Canada | 40.363 ms (**x33.13**) | 427.40 ms (**x350.90**) | 25.50 ms (**x20.93**) | 1.218 ms | 1.217 ms (**x0.99**) |
| CITM catalog | 5.357 ms (**x2.51**) | 39.215 ms (**x18.44**) | 1.58 ms (**x0.74**) | 2.126 ms | 569.23 us (**x0.26**) |
| Fast (valid) | 2.27 us (**x4.87**) | 6.55 us (**x14.05**) | 542.2 us (**x1.16**) | 465.89 ns | 113.94 ns (**x0.24**) |
| Fast (invalid) | 412.21 ns (**x0.46**) | 6.69 us (**x7.61**) | 787.12 us (**x0.89**) | 878.23 ns | 4.21ns (**x0.004**) |
Notes:
1. `jsonschema_valid` and `valico` do not handle valid path instances matching the `^\\/` regex.
2. `jsonschema_valid` fails to resolve local references (e.g. `#/definitions/definitions`).
You can find benchmark code in `benches/jsonschema.rs`, Rust version is `1.78`.
## Support
If you have anything to discuss regarding this library, please, join our [gitter](https://gitter.im/Stranger6667/jsonschema-rs)!