Documentation: https://www.encode.io/typesystem/

TypeSystem is a comprehensive data validation library that gives you:

• Data validation.
• Object serialization & deserialization.
• Form rendering.
• Marshaling validators to/from JSON schema.
• Tokenizing JSON or YAML to provide positional error messages.
• 100% type annotated codebase.
• 100% test coverage.
• Zero hard dependencies.

Python 3.6+

$ pip3 install typesystem

If you'd like you use the form rendering you'll also want to install jinja2.

$ pip3 install jinja2

If you'd like you use the YAML tokenization you'll also want to install pyyaml.

$ pip3 install pyyaml

import typesystem

class Artist(typesystem.Schema):
    name = typesystem.String(max_length=100)

class Album(typesystem.Schema):
    title = typesystem.String(max_length=100)
    release_date = typesystem.Date()
    artist = typesystem.Reference(Artist)

album = Album.validate({
    "title": "Double Negative",
    "release_date": "2018-09-14",
    "artist": {"name": "Low"}
})

print(album)
# Album(title='Double Negative', release_date=datetime.date(2018, 9, 14), artist=Artist(name='Low'))

print(album.release_date)
# datetime.date(2018, 9, 14)

print(album['release_date'])
# '2018-09-14'

print(dict(album))
# {'title': 'Double Negative', 'release_date': '2018-09-14', 'artist': {'name': 'Low'}}

There are plenty of other great validation libraries for Python out there, including Marshmallow, Schematics, Voluptuous, and many others.

TypeSystem exists because I want a data validation library that offers first-class support for:

• Rendering validation classes into HTML forms.
• Marshaling to/from JSON Schema.
• Obtaining positional errors within JSON or YAML documents.

— ⭐️ —

TypeSystem is BSD licensed code. Designed & built in Brighton, England.