{
    "username": {"type": "string", "length": 10},
    "age": {"type": "integer", "min": 18, "max": 99},
    "email": {"type": "email"},
    "isActive": {"type": "boolean"},
    "createdAt": {"type": "date", "min": "2000-01-01", "max": "2022-12-31"}
}