Cornice: A REST framework for Pyramid

Cornice provides helpers to build & document REST-ish Web Services with Pyramid, with decent default behaviors. It takes care of following the HTTP specification in an automated way where possible.

We designed and implemented cornice in a really simple way, so it is easy to use and you can get started in a matter of minutes.

Show me some code!

A full Cornice WGSI application looks like this (this example is taken from the demoapp project):

from collections import defaultdict

from pyramid.exceptions import Forbidden
from import authenticated_userid, effective_principals
from pyramid.view import view_config

from cornice import Service

info_desc = """\
This service is useful to get and set data for a user.

user_info = Service(name='users', path='/{username}/info',

_USERS = defaultdict(dict)

def get_info(request):
    """Returns the public information about a **user**.

    If the user does not exists, returns an empty dataset.
    username = request.matchdict['username']
    return _USERS[username]
def set_info(request):
    """Set the public information for a **user**.

    You have to be that user, and *authenticated*.

    Returns *True* or *False*.
    username = authenticated_userid(request)
    if request.matchdict["username"] != username:
        raise Forbidden()
    _USERS[username] = request.json_body
    return {'success': True}

@view_config(route_name="whoami", permission="authenticated", renderer="json")
def whoami(request):
    """View returning the authenticated user's credentials."""
    username = authenticated_userid(request)
    principals = effective_principals(request)
    return {"username": username, "principals": principals}

What Cornice will do for you here is:

  • automatically raise a 405 if a DELETE or a PUT is called on /{username}/info
  • automatically generate your doc via a Sphinx directive.
  • provide a validation framework that will return a nice JSON structure in Bad Request 400 responses explaining what’s wrong.
  • provide an acceptable Content-Type whenever you send an HTTP “Accept” header to it, resulting in a 406 Not Acceptable with the list of acceptable ones if it can’t answer.

Please follow up with Exhaustive list of the validations provided by Cornice to get the picture.

Contribution & Feedback

Cornice is a project initiated at Mozilla Services, where we build Web Services for features like Firefox Sync. All of what we do is built with open source, and this is one brick of our stack.

We welcome Contributors and Feedback!