Klein controller concept

_KleinController.py

"""A basic controller concept for Twisted based micro web framework Klein"""

app.py

from klein import Klein

import user

app = Klein()

user.UserController(app, namespace='user')

app.run('localhost', 8080)

controller.py

class Controller(object):
    _routes = {}

    def __init__(self, app, namespace=None):
        """
        :param klein.Klein app:
        :param str or None namespace:
        """
        self.namespace = namespace or self.__class__.__name__
        self.app = app

        with app.subroute('/' + self.namespace) as app:
            for url, route_kwargs in getattr(self, '_routes', {}).items():
                action = route_kwargs.pop('action')
                if not action:
                    continue

                func = getattr(self, action)
                endpoint = ':'.join([self.namespace, action])
                route_kwargs['endpoint'] = endpoint

                new_func = app.route(url, **route_kwargs)(func)
                setattr(self, action, new_func)

user_controller.py

import json

from bson import json_util
from twisted.internet import defer

from controller import Controller


class UserController(Controller):
    _routes = {
        '/': {
            'action': 'index',
            'methods': ['GET'],
        },
        '/create': {
            'action': 'create',
            'methods': ['POST', 'PUT'],
        },
        '/get/<int:id>': {
            'action': 'get_by_id',
            'methods': ['GET'],
        },
        '/get/<string:username>': {
            'action': 'get_by_username',
            'methods': ['GET'],
        },
    }

    def index(self, request):
        """List all users

        :param twisted.web.http.Request request:
        :rtype: str
        """
        return 'User list'

    def create(self, request):
        """Create a user

        Notice: do not accept user input as is, I would use jsonschema here, but that is just me...

        :param twisted.web.http.Request request: 
        """
        username = request.args.get('username')
        return 'Creating user with name {}'.format(username)

    def get_by_id(self, request, id):
        """Get user by its ID

        :param twisted.web.http.Request request:
        :param int id:
        :rtype: twisted.internet.defer.Deferred
        """
        d = self.app.mongo.users.find({'id': id})
        d.addCallback(self._get_user, request)
        return d

    def get_by_username(self, request, username):
        """Get user by its ID

        :param twisted.web.http.Request request:
        :param str username:
        :rtype: twisted.internet.defer.Deferred
        """
        d = self.app.mongo.users.find({'username': username})
        d.addCallback(self._get_user, request)
        return d

    def _get_user(self, user, request):
        if not user:
            return defer.fail()

        request.setHeader(b'content-type', b'application/json')
        return defer.succeed(json.dumps(user, default=json_util.default))