imclab / schematics

Python Data Structures for Humans™.

Schematics

Python Data Structures for Humans™.

For more information, please see our documentation.

About

Schematics is a Python library to combine types into structures, validate them, and transform the shapes of your data based on simple descriptions.

The internals are similar to ORM type systems, but there is no database layer in Schematics. Instead, Schematics believes the task of building a database layer is made significantly easier when Schematics handles everything but writing the query.

Further, it can be used for a range of tasks where having a database involved may not make sense.

Some common use cases:

• Design and document specific data structures for code
• Convert structures to and from different formats, like JSON or MsgPack
• Validate API inputs
• Remove fields based on access rights of some data's recipient
• Define message formats for communications protocols, like an RPC
• Custom persistence layers.

Examples

This is a simple Model.

>>> from schematics.models import Model
>>> from schematics.types import StringType, URLType
>>> class Person(Model):
...     name = StringType(required=True)
...     website = URLType()
...
>>> person = Person({'name': u'Joe Strummer',
...                  'website': 'http://soundcloud.com/joestrummer'})
>>> person.name
u'Joe Strummer'

Serializing the data to JSON.

>>> import json
>>> json.dumps(person.to_primitive())
{"name": "Joe Strummer", "website": "http://soundcloud.com/joestrummer"}

Let's try validating without a name value, since it's required.

>>> person = Person()
>>> person.website = 'http://www.amontobin.com/'
>>> person.validate()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "schematics/models.py", line 231, in validate
    raise ModelValidationError(e.messages)
schematics.exceptions.ModelValidationError: {'name': [u'This field is required.']}

Add the field and validation passes

>>> person = Person()
>>> person.name = 'Amon Tobin'
>>> person.website = 'http://www.amontobin.com/'
>>> person.validate()
>>>