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Lightweight WSGI application framework, schema-validated JSON APIs, and API documentation.

Project description

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Chisel is a light-weight Python WSGI application framework built for creating well-documented, schema-validated JSON web APIs. Here are its features at a glance:

  • Light-weight WSGI application framework
  • Schema-validated JSON APIs
  • API documentation with Markdown support
  • Written in pure Python
  • Zero dependencies

Schema-Validated JSON APIs

Chisel provides the action decorator for easily implementing schema-validated JSON APIs.

>>> @chisel.action(spec='''
... # Sum a list of numbers
... action sum_numbers
...     urls
...        GET
...     query
...         # The list of numbers
...         float[len > 0] numbers
...     output
...         # The sum of the numbers
...         float sum
... ''')
... def sum_numbers(ctx, req):
...     return {'sum': sum(req['numbers'])}
>>> application = chisel.Application()
>>> application.add_request(sum_numbers)
>>> application.request('GET', '/sum_numbers', query_string='numbers.0=1&numbers.1=2&numbers.2=4')
('200 OK', [('Content-Type', 'application/json')], b'{"sum":7.0}')

Each action defines an action definition using Schema Markdown. The action callback is passed two arguments, a request Context and the schema-validated request input dictionary. The input request dictionary is created by combining the request’s URL path parameters, query string parameters, and input JSON content parameters.

If there is a schema validation error the appropriate error code is automatically returned.

>>> status, _, content_bytes = application.request('GET', '/sum_numbers')
>>> status
'400 Bad Request'
>>> content_bytes
b'{"error":"InvalidInput","message":"Required member \'numbers\' missing (query string)"}'

API Documentation

You can add API documentation to your application by adding the Chisel documentation application requests from create_doc_requests.

>>> application = chisel.Application()
>>> application.add_requests(chisel.create_doc_requests())

By default the documentation application is hosted at “/doc/”. An example of of Chisel’s documentation output is available here.


This project is developed using python-build. It was started using python-template as follows:

template-specialize python-template/template/ chisel/ -k package chisel -k name 'Craig A. Hobbs' -k email '' -k github 'craigahobbs' -k nomain 1

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