About dschema

dschema is a small library for validating the content of python dictionary objects against a schema.

The schema can be defined in code or entirely as text (parsed from json generally)

dschema was mainly made for validating config files written in JSON.

Example

See documentation link for more examples

import re
import phonenumbers
import dschema


# https://github.com/daviddrysdale/python-phonenumbers
# pip install phonenumbers


def phone_type(number):
    # Exceptions are validation errors
    # Very similar design to the "argparse" module
    return phonenumbers.parse(number)


def ssn_type(ssn):
    if re.match('^\d{3}-?\d{2}-?\d{4}$', ssn):
        return ssn
    else:
        raise ValueError('"{}" is not a valid SSN.')


schema = {
    'person': {
        'first_name': dschema.prop(required=True),
        'last_name': dschema.prop(required=True),
        'phone': dschema.prop(required=True, type=phone_type),
        'ssn': dschema.prop(required=True, type='ssn_type'),

        dschema.Required: True
        # "person" namespace is required, you must specify
        # even if "person" itself contains required properties
    },

    # Allow a raw dictionary value to pass through

    'other_info': dschema.prop(default=dict(), dict=True),

    # default to False if not present

    'subscribed': dschema.prop(default=False, type=bool)
}

validator = dschema.Validator(schema)

# you can use this to add types that are recognized by name.
# which is useful if you want your schema to be entirely textual

validator.add_type('ssn_type', ssn_type)

# you will need to define default types on your own
# if you want to reference them by name

# validator.add_type('int', int)


data = {
    'person': {
        'first_name': "John",
        'last_name': "Smith",
        'phone': '+1 234 5678 9000',
        'ssn': '123-45-6789'
    },

    'other_info': {
        'website': 'www.johnsmith.com',
    }
}

# If namespace is left False, a plain dictionary is returned

result = validator.validate(data, namespace=True)

print(result)

# Prints: (un-indented)

# Namespace(
#     person=Namespace(
#         first_name='John',
#         last_name='Smith',
#         phone=PhoneNumber(...),
#         ssn='123-45-6789'),
#     other_info={'website': 'www.johnsmith.com'},
#     subscribed=False
# )


# Each Namespace is just a dynamic object

print(result.person.first_name)  # -> John
print(result.person.last_name)  # -> Smith

print(result.person.phone)
# - > Country Code: 1 National Number: 23456789000

print(result.person.ssn)  # -> 123-45-6789

print(result.other_info)  # -> {'website': 'www.johnsmith.com'}

print(result.subscribed)  # -> False (default)