Event Sourcing with Django

This package supports using the Python eventsourcing library with Django ORM.

To use Django with your Python eventsourcing applications:

• install the Python package eventsourcing_django
• add 'eventsourcing_django' to your Django project's INSTALLED_APPS setting
• migrate your database for this Django app
• set the environment variable PERSISTENCE_MODULE to 'eventsourcing_django'

See below for more information.

Installation

Use pip to install the stable distribution from the Python Package Index. Please note, it is recommended to install Python packages into a Python virtual environment.

$ pip install eventsourcing_django

Django

If you are using Django 3.2 or later, add 'eventsourcing_django' to your Django project's INSTALLED_APPS setting.

INSTALLED_APPS = [
    ...
    'eventsourcing_django',
]

If you are using Django 2.2, 3.0 or 3.1, please add 'eventsourcing_django.apps.EventsourcingConfig' to your Django project's INSTALLED_APPS setting.

INSTALLED_APPS = [
    ...
    'eventsourcing_django.apps.EventsourcingConfig',
]

To migrate your database, please run Django's manage.py migrate command.

$ python manage.py migrate eventsourcing_django

Event sourcing

Define aggregates and applications in the usual way.

from eventsourcing.application import Application
from eventsourcing.domain import Aggregate, event
from uuid import uuid5, NAMESPACE_URL


class TrainingSchool(Application):
    def register(self, name):
        dog = Dog(name)
        self.save(dog)

    def add_trick(self, name, trick):
        dog = self.repository.get(Dog.create_id(name))
        dog.add_trick(trick)
        self.save(dog)

    def get_tricks(self, name):
        dog = self.repository.get(Dog.create_id(name))
        return dog.tricks


class Dog(Aggregate):
    @event('Registered')
    def __init__(self, name):
        self.name = name
        self.tricks = []

    @staticmethod
    def create_id(name):
        return uuid5(NAMESPACE_URL, f'/dogs/{name}')

    @event('TrickAdded')
    def add_trick(self, trick):
        self.tricks.append(trick)

Construct and use the application in the usual way. Set PERSISTENCE_MODULE to 'eventsourcing_django' in the application's environment. You may wish to construct the application object on a signal when the Django project is "ready". You can use the ready() method of the AppConfig class in the apps.py module of a Django app.

school = TrainingSchool(env={
    "PERSISTENCE_MODULE": "eventsourcing_django",
})

The application's methods may be called from Django views and forms.

school.register('Fido')
school.add_trick('Fido', 'roll over')
school.add_trick('Fido', 'play dead')
tricks = school.get_tricks('Fido')
assert tricks == ['roll over', 'play dead']

For more information, please refer to the Python eventsourcing library and the Django project.