JSON Schema Validator

Validate JSON documents against JSON Schema (Draft 7) specifications.

Features

• Schema Validation: Validate JSON against schema
• Error Details: Detailed validation error messages
• Batch Validation: Validate multiple files
• Schema Generation: Generate schema from examples
• Multiple Drafts: Support for Draft 4, 6, 7

Quick Start

from json_validator import JSONValidator

validator = JSONValidator()

# Validate data against schema
schema = {
    "type": "object",
    "properties": {
        "name": {"type": "string"},
        "age": {"type": "integer", "minimum": 0}
    },
    "required": ["name"]
}

data = {"name": "John", "age": 30}
result = validator.validate(data, schema)
print(f"Valid: {result['valid']}")

CLI Usage

# Validate JSON file against schema
python json_validator.py --data user.json --schema user_schema.json

# Validate with inline schema
python json_validator.py --data config.json --schema '{"type": "object"}'

# Generate schema from sample
python json_validator.py --generate sample.json --output schema.json

# Batch validate directory
python json_validator.py --data-dir ./configs/ --schema config_schema.json

API Reference

JSONValidator Class

class JSONValidator:
    def __init__(self, draft: str = "draft7")

    # Validation
    def validate(self, data: dict, schema: dict) -> dict
    def validate_file(self, data_path: str, schema_path: str) -> dict
    def validate_batch(self, data_files: list, schema: dict) -> list

    # Schema operations
    def generate_schema(self, data: dict) -> dict
    def check_schema(self, schema: dict) -> dict

Validation Result

{
    "valid": True,  # or False
    "errors": [],   # List of error details
    "path": "$",    # JSON path to data root
}

# With errors:
{
    "valid": False,
    "errors": [
        {
            "message": "'name' is a required property",
            "path": "$",
            "schema_path": "required"
        },
        {
            "message": "-5 is less than minimum 0",
            "path": "$.age",
            "schema_path": "properties.age.minimum"
        }
    ]
}

Schema Examples

Object Schema

schema = {
    "type": "object",
    "properties": {
        "id": {"type": "integer"},
        "name": {"type": "string", "minLength": 1},
        "email": {"type": "string", "format": "email"},
        "active": {"type": "boolean", "default": True}
    },
    "required": ["id", "name", "email"],
    "additionalProperties": False
}

Array Schema

schema = {
    "type": "array",
    "items": {
        "type": "object",
        "properties": {
            "id": {"type": "integer"},
            "value": {"type": "number"}
        }
    },
    "minItems": 1,
    "uniqueItems": True
}

Nested Schema

schema = {
    "type": "object",
    "properties": {
        "user": {
            "type": "object",
            "properties": {
                "name": {"type": "string"},
                "address": {
                    "type": "object",
                    "properties": {
                        "street": {"type": "string"},
                        "city": {"type": "string"}
                    }
                }
            }
        }
    }
}

Generate Schema from Data

validator = JSONValidator()

sample_data = {
    "name": "Product A",
    "price": 29.99,
    "tags": ["electronics", "sale"],
    "inStock": True
}

schema = validator.generate_schema(sample_data)
# Returns inferred schema based on data types

Supported Keywords

Type Validation

• type: string, number, integer, boolean, array, object, null
• enum: allowed values
• const: exact value

String Validation

• minLength, maxLength
• pattern: regex pattern
• format: email, uri, date, date-time, ipv4, ipv6, uuid

Number Validation

• minimum, maximum
• exclusiveMinimum, exclusiveMaximum
• multipleOf

Array Validation

• items: schema for items
• minItems, maxItems
• uniqueItems
• contains

Object Validation

• properties: property schemas
• required: required properties
• additionalProperties
• minProperties, maxProperties
• patternProperties

Error Handling

result = validator.validate(data, schema)

if not result['valid']:
    for error in result['errors']:
        print(f"Error at {error['path']}: {error['message']}")

Dependencies

• jsonschema>=4.20.0