jsonschema

A JSON Schema validator implementation. It compiles schema into a validation tree to have validation as fast as possible.

Supported drafts:

• Draft 7
• Draft 6
• Draft 4 (except optional bignum.json test case)

# Cargo.toml
jsonschema = "0.3"

To validate documents against some schema and get validation errors (if any):

use jsonschema::{JSONSchema, Draft};
use serde_json::json;

fn main() {
    let schema = json!({"maxLength": 5});
    let instance = json!("foo");
    let compiled = JSONSchema::compile(&schema, Some(Draft::Draft7));
    let result = compiled.validate(&instance);
    if let Err(errors) = result {
        for error in errors {
            println!("Validation error: {}", error)
        }   
    }
}

If you only need to know whether document is valid or not (which is faster):

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):

use jsonschema::{JSONSchema, Draft};
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, None);
    assert!(compiled.is_valid(&instance));
}

Performance

There is a comparison with other JSON Schema validators written in Rust - jsonschema_valid and valico.

Test machine i8700K (12 cores), 32GB RAM.

Performance of jsonschema::JSONSchema.is_valid. Ratios are given against compiled jsonschema:

• Big valid input (canada_schema.json and canada.json)
• Small valid input (small_schema.json and small_valid.json)
• Small invalid input (small_schema.json and small_invalid.json)

As you can see the compiled version is faster, especially for large inputs. However, not-compiled version is slower on smaller inputs than jsonschema_valid.

You can find benchmark code in benches/jsonschema.rs

NOTE. This library is in early development.