more.emit: pymitter integration in Morepath

This package provides Morepath integration for pymitter.

pymitter is a Python port of the extended Node.js EventEmitter 2 approach providing namespaces, wildcards and TTL.

Quick start

Install more.emit:

$ pip install -U more.emit

Extend your App class from EmitApp:

from more.emit import EmitApp

class App(EmitApp):
    pass

Now you can define signals:

from .app import App


@App.signal.on('myevent')
def handler1(arg, request):
    print(request)
    print('handler1 called with', arg)

@App.signal.on('myevent')
def handler2(arg, request):
    print('handler2 called with', arg)

You can emit the signals for example from the view:

@App.json(model=Root)
def root_view(self, request):
    request.app.signal.emit('myevent', 'foo', request)
    return {
        'name': 'Root'
    }

Example

An example for emitting signals on user creation and user update for sending a confirmation email. This example uses more.pony.

signal.py

from .app import App


@App.signal.on('user.email_updated')
def send_confirmation_email(user, request):
    mailer = request.app.service(name='mailer')
    mailer.send_confirmation_email(user, request)

view.py

@App.json(model=UserCollection, request_method='POST')
def user_collection_add(self, request):
    email = request.json['email']

    if not User.exists(email=email):
        user = self.add(email=email)

        @request.after
        def after(response):
            request.app.signal.emit('user.email_updated', user, request)
            response.status = 201

    else:
        @request.after
        def after(response):
            response.status = 409

        return {
            'validationError': 'Email already exists'
        }


@App.json(model=User, request_method='PUT')
def user_update(self, request):
    if 'email' in request.json and User.exists(email=request.json['email']):
        @request.after
        def after(response):
            response.status = 409

        return {
            'validationError': 'Email already exists'
        }

    else:
        self.update(request.json)
        if 'email' in request.json:
            self.email_confirmed = False

            @request.after
            def after(response):
                request.app.signal.emit('user.email_updated', self, request)