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Workshop:

�Sharing the joys of the Django ORM with Python Notebooks

GREENWEB.ORG

Chris

Adams

2025.04.24

Djangocon Europe 2025

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Hello, I’m Chris!

My background:

Loco2 - Low CO2 Travel in Europe by train

A.M.E.E (Avoid Mass Extinction Engine) - CO2 calcs as an API

Green Software Foundation - Policy chair

Branch Magazine - editor

Green Web Foundation - make the web green

Environment Variables podcast - co-host

Django Fundraising Working Group - newest member!

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Agenda

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Housekeeping
Primer: Using the Django ORM and Python notebooks together ~ 10 mins
Trying it out with Marimo ~25mins
Where to go next ~10mins

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Housekeeping

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About the workshop

Aim:

Duration: 50 mins

You will need:

A laptop (or share with someone)
A working internet connection
A modern browser
A Github account (ok, not essential, but it really helps)

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About the Green Web Foundation

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The Green Web Foundation is working towards a fossil-free internet by 2030.

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“

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Build open source tools, APIs, and libraries

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Create prototypes.

Contribute to open source projects.

Publish open data.

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Talks.

Workshops.

Training.

Consulting.

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Learning objectives

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Learn how to use Django from a notebook environment

Learn to turn a Django query into a simple dashboard

Get confidence to try on your own project

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Accessing this deck

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This deck is online.

�Point a camera at the QR

code:

https://www.thegreenwebfoundation.org/events/djangocon-europe-2025

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Exploring along

Follow along:

github.com/mrchrisadams/djangocon-eu-2025-workshop

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Agenda

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Housekeeping ✅
Primer: Using the Django ORM and Python notebooks together ~ 10 mins
Trying it out with Marimo ~25mins
Where to go next ~5mins

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Primer: Using the Django ORM and Python notebooks together

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Who here has used Django Shell?

(uv run) manage.py shell

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Exploring a sample app & db - Northwind

Commonly used training database, to simulate an e-commerce company.

Lots of tables, and models.

Data already available as a handy fixture for us to mess around with.

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Don’t panic!

Don’t worry! We’re only looking at a couple of tables today!

Customers, and Orders

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Customers

class Customer(models.Model):

customer_id = models.CharField("Customer ID", primary_key=True)

company_name = models.CharField("Company name, max_length=40)

contact_name = models.CharField(

"Contact name", max_length=30, blank=True, null=True

)

(snip)

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Orders

class Order(models.Model):

order_id = models.AutoField(_("Order ID"), primary_key=True)

customer = models.ForeignKey( Customer, blank=True, null=True,

on_delete=models.CASCADE

)

employee = models.ForeignKey(Employee, blank=True, null=True,

on_delete=models.CASCADE,

)

order_date = models.DateField(

“Order date", blank=True, null=True, db_index=True)

(snip)

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Easy

How many customers are there?

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Harder

Who were the 10 customers who placed the most orders?

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how do I share these results?

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two main options for notebooks in 2025

dj-notebook - use jupyter (common data science tool) to access the Django ORM

marimo - new, slightly more pythonic project, that addresses a few common pain points of jupyter notebooks

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DJ notebook

order of cells matters (hidden state)

can run multiple languages, not just python

more established, bigger ecosystem

saves as .ipynb files (json files)

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Marimo

order of cells does not matter

mainly python focussed

fewer moving parts

saves as .py or .md files

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Agenda

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Housekeeping ✅
Primer: Using the Django ORM and Python notebooks together ~ 10 mins ✅
Trying it out with Marimo ~25mins
Where to go next ~10mins

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Trying it out with Marimo

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What is Marimo?

“marimo is an open-source reactive notebook for Python — reproducible, git-friendly, SQL built-in, executable as a script, and shareable as an app.”

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how to run it - uv run marimo

Usage: marimo [OPTIONS] COMMAND [ARGS]...

Welcome to marimo!

Getting started:

* marimo tutorial intro

Example usage:

* marimo edit create or edit notebooks

* marimo edit notebook.py create or edit a notebook called notebook.py

* marimo run notebook.py run a notebook as a read-only app

* marimo tutorial --help list tutorials

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how to run it

uv run marimo edit /path/to/file

(opens that notebook. Can be python or markdown)

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making this concrete

uv run marimo edit \�./notebooks/who-are-our-customers.md

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how this is working - django helper

def setup_django_for_marimo(main_project_path=None, set_async_unsafe=True):

os.environ.setdefault("DJANGO_SETTINGS_MODULE", "django_project.settings")

if not main_project_path:

main_project_path = find_django_project()

# if we want to run queries a notebook environment we need to set this

if set_async_unsafe:

os.environ["DJANGO_ALLOW_ASYNC_UNSAFE"] = "True"

if main_project_path not in sys.path:

sys.path.append(main_project_path)

return django.setup()

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Easy

Which city has the most customers?

(Hint: Update the widgets to filter listings by city, instead of country)

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Harder

Which 3 customers placed the largest orders?�

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follow along

uv run marimo edit \�./notebooks/all-time-biggest-spenders.md

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Can I have a dashboard plz?

Which 3 customers placed the largest number of orders?�

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follow along

uv run marimo edit \�./notebooks/customer-order-dashboard.py

�# run in dashboard more

uv run marimo run \�./notebooks/customer-order-dashboard.py

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Agenda

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Housekeeping ✅
Primer: Using the Django ORM and Python notebooks together ~ 10 mins
Trying it out with Marimo ~25mins
Where to go next ~10mins

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There is LOADS to Marimo.

Play with the features some more:

�uv run marimo tutorial

�Main website - check the gallery!�https://marimo.io/

Excellent videos�https://www.youtube.com/@marimo-team

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Thanks! I’ll be at the sprints if you want more

Please take 5 mins to provide the feedback form over lunch.

chris@greenweb.org

www.linkedin.com/in/mrchrisadams

mastodon.social/@mrchrisadams�

climateAction.tech - a supportive climate-tech community

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