Validating Data with Standard JSON Schema Tools

Validating Data with Standard JSON Schema Tools#

Because FAIR Data JSON Schema relies on standard JSON Schema Draft 2020-12 extension mechanisms ($vocabulary, custom dialect, metadata annotations), you can validate your data using any standard JSON Schema validator across any programming language out of the box.

Standard validators perform technical data validation and treat fair: keywords as transparent metadata annotations.

1. Python (jsonschema package)#

Standard Python jsonschema validates FAIR-annotated schemas without requiring any plugins.

Installation#

pip install jsonschema

Usage#

import json
from jsonschema import validate, ValidationError

# Load schema and data instance
with open("examples/simple-dataset.json") as f:
    schema = json.load(f)

with open("examples/simple-dataset.data.json") as f:
    data = json.load(f)

# Validate data instance against schema
try:
    validate(instance=data, schema=schema)
    print("✓ Data is valid!")
except ValidationError as e:
    print(f"✗ Validation error: {e.message}")
    print(f"  Path: {list(e.absolute_path)}")

2. JavaScript / Node.js (ajv package)#

Ajv is the most popular JSON Schema validator in the JavaScript and TypeScript ecosystem. Use the Draft 2020-12 build (ajv/dist/2020).

Installation#

npm install ajv

Usage#

const Ajv2020 = require("ajv/dist/2020");
const fs = require("fs");

const ajv = new Ajv2020();

const schema = JSON.parse(fs.readFileSync("examples/simple-dataset.json", "utf8"));
const data = JSON.parse(fs.readFileSync("examples/simple-dataset.data.json", "utf8"));

const validate = ajv.compile(schema);
const valid = validate(data);

if (valid) {
  console.log("✓ Data is valid!");
} else {
  console.log("✗ Validation errors:", validate.errors);
}

3. Command-Line Validation (CLI)#

Option A: fair-data-schema CLI#

Use the built-in FAIR CLI for dialect-aware validation and schema checking:

fair-data-schema validate examples/simple-dataset.json examples/simple-dataset.data.json

Option B: Standard check-jsonschema CLI#

Use the generic check-jsonschema tool used in CI/CD pipelines:

pip install check-jsonschema

check-jsonschema --schemafile examples/simple-dataset.json examples/simple-dataset.data.json

4. Python SDK (fair_data_schema package)#

The fair_data_schema Python package wraps jsonschema with offline local URI resolution so $ref pointers resolve without needing an internet connection:

from pathlib import Path
from fair_data_schema import validator

schema_path = Path("examples/simple-dataset.json")
instance_path = Path("examples/simple-dataset.data.json")

errors = validator.validate_file(schema_path, instance_path)

if not errors:
    print("✓ Data is valid!")
else:
    for err in errors:
        print(f"✗ {err.message} at {list(err.absolute_path)}")

5. Summary Matrix across Languages#

Language / Tool

Library

Draft 2020-12 Support

Out-of-the-Box FAIR Support

Python

jsonschema

Native

✅ 100% Validated

JavaScript / TS

ajv (ajv/dist/2020)

Native

✅ 100% Validated

Go

santhosh-tekuri/jsonschema/v5

Native

✅ 100% Validated

Rust

boon / jsonschema

Native

✅ 100% Validated

Java

networknt/json-schema-validator

Native

✅ 100% Validated

C# / .NET

JsonSchema.Net

Native

✅ 100% Validated

CLI

check-jsonschema

Native

✅ 100% Validated