Simon Willison’s Weblog

Is async Django ready for prime time? (via) Jonathan Adly reports on his experience using Django to build ColiVara, a hosted RAG API that uses ColQwen2 visual embeddings, inspired by the ColPali paper.

In a breach of Betteridge's law of headlines the answer to the question posed by this headline is “yes”.

We believe async Django is ready for production. In theory, there should be no performance loss when using async Django instead of FastAPI for the same tasks.

The ColiVara application is itself open source, and you can see how it makes use of Django’s relatively new asynchronous ORM features in the api/views.py module.

I also picked up a useful trick from their Dockerfile: if you want uv in a container you can install it with this one-liner:

COPY --from=ghcr.io/astral-sh/uv:latest /uv /bin/uv

# 24th November 2024, 5:47 pm / embeddings, asynchronous, django, uv, rag, python

django-plugin-django-debug-toolbar (via) Tom Viner built a plugin for my DJP Django plugin system that configures the excellent django-debug-toolbar debugging tool.

You can see everything it sets up for you in this Python code: it configures installed apps, URL patterns and middleware and sets the INTERNAL_IPS and DEBUG settings.

Here are Tom's running notes as he created the plugin.

# 13th November 2024, 1:14 am / djp, django, plugins

2025 DSF Board Nominations. The Django Software Foundation board elections are coming up. There are four positions open, seven directors total. Terms last two years, and the deadline for submitting a nomination is October 25th (the date of the election has not yet been decided).

Several community members have shared "DSF initiatives I'd like to see" documents to inspire people who may be considering running for the board:

• Sarah Boyce (current Django Fellow) wants a marketing strategy, better community docs, more automation and a refresh of the Django survey.
• Tim Schilling wants one big sponsor, more community recognition and a focus on working groups.
• Carlton Gibson wants an Executive Director, an updated website and better integration of the community into that website.
• Jacob Kaplan-Moss wants effectively all of the above.

There's also a useful FAQ on the Django forum by Thibaud Colas.

# 16th October 2024, 11:01 pm / django, dsf, jacob-kaplan-moss

jefftriplett/django-startproject (via) Django's django-admin startproject and startapp commands include a --template option which can be used to specify an alternative template for generating the initial code.

Jeff Triplett actively maintains his own template for new projects, which includes the pattern that I personally prefer of keeping settings and URLs in a config/ folder. It also configures the development environment to run using Docker Compose.

The latest update adds support for Python 3.13, Django 5.1 and uv. It's neat how you can get started without even installing Django using uv run like this:

uv run --with=django django-admin startproject \
  --extension=ini,py,toml,yaml,yml \
  --template=https://github.com/jefftriplett/django-startproject/archive/main.zip \
  example_project

# 12th October 2024, 11:19 pm / uv, jeff-triplett, django, python, docker

If we had $1,000,000…. Jacob Kaplan-Moss gave my favorite talk at DjangoCon this year, imagining what the Django Software Foundation could do if it quadrupled its annual income to $1 million and laying out a realistic path for getting there. Jacob suggests leaning more into large donors than increasing our small donor base:

It’s far easier for me to picture convincing eight or ten or fifteen large companies to make large donations than it is to picture increasing our small donor base tenfold. So I think a major donor strategy is probably the most realistic one for us.

So when I talk about major donors, who am I talking about? I’m talking about four major categories: large corporations, high net worth individuals (very wealthy people), grants from governments (e.g. the Sovereign Tech Fund run out of Germany), and private foundations (e.g. the Chan Zuckerberg Initiative, who’s given grants to the PSF in the past).

Also included: a TIL on Turning a conference talk into an annotated presentation. Jacob used my annotated presentation tool to OCR text from images of keynote slides, extracted a Whisper transcript from the YouTube livestream audio and then cleaned that up a little with LLM and Claude 3.5 Sonnet ("Split the content of this transcript up into paragraphs with logical breaks. Add newlines between each paragraph.") before editing and re-writing it all into the final post.

# 8th October 2024, 7:59 pm / jacob-kaplan-moss, django, dsf, claude-3-5-sonnet, llm, whisper

Django Commons. Django Commons is a really promising initiative started by Tim Schilling, aimed at the problem of keeping key Django community projects responsibly maintained on a long-term basis.

Django Commons is an organization dedicated to supporting the community's efforts to maintain packages. It seeks to improve the maintenance experience for all contributors; reducing the barrier to entry for new contributors and reducing overhead for existing maintainers.

I’ve stated recently that I’d love to see the Django Software Foundation take on this role - adopting projects and ensuring they are maintained long-term. Django Commons looks like it solves that exact problem, assuring the future of key projects beyond their initial creators.

So far the Commons has taken on responsibility for django-fsm-2, django-tasks-scheduler and, as-of this week, diango-typer.

Here’s Tim introducing the project back in May. Thoughtful governance has been baked in from the start:

Having multiple administrators makes the role more sustainable, lessens the impact of a person stepping away, and shortens response time for administrator requests. It’s important to me that the organization starts with multiple administrators so that collaboration and documentation are at the forefront of all decisions.

# 8th October 2024, 3:27 am / open-source, django

Thoughts on the Treasurer Role at Tech NonProfits. Will Vincent, Django Software Foundation treasurer from 2020-2022, explains what’s involved in the non-profit role with the highest level of responsibility and trust.

# 7th October 2024, 10:41 pm / dsf, django

Building an automatically updating live blog in Django. Here's an extended write-up of how I implemented the live blog feature I used for my coverage of OpenAI DevDay yesterday. I built the first version using Claude while waiting for the keynote to start, then upgraded it during the lunch break with the help of GPT-4o to add sort options and incremental fetching of new updates.

# 2nd October 2024, 3:42 pm / claude, ai, django, llms, javascript, ai-assisted-programming, generative-ai, chatgpt

Ensuring a block is overridden in a Django template (via) Neat Django trick by Tom Carrick: implement a Django template tag that raises a custom exception, then you can use this pattern in your templates:

{% block title %}{% ensure_overridden %}{% endblock %}

To ensure you don't accidentally extend a base template but forget to fill out a critical block.

# 29th September 2024, 7:25 pm / django, python

DjangoTV (via) Brand new site by Jeff Triplett gathering together videos from Django conferences around the world. Here's Jeff's blog post introducing the project.

# 28th September 2024, 4:48 am / jeff-triplett, django

django-plugin-datasette. I did some more work on my DJP plugin mechanism for Django at the DjangoCon US sprints today. I added a new plugin hook, asgi_wrapper(), released in DJP 0.3 and inspired by the similar hook in Datasette.

The hook only works for Django apps that are served using ASGI. It allows plugins to add their own wrapping ASGI middleware around the Django app itself, which means they can do things like attach entirely separate ASGI-compatible applications outside of the regular Django request/response cycle.

Datasette is one of those ASGI-compatible applications!

django-plugin-datasette uses that new hook to configure a new URL, /-/datasette/, which serves a full Datasette instance that scans through Django’s settings.DATABASES dictionary and serves an explore interface on top of any SQLite databases it finds there.

It doesn’t support authentication yet, so this will expose your entire database contents - probably best used as a local debugging tool only.

I did borrow some code from the datasette-mask-columns plugin to ensure that the password column in the auth_user column is reliably redacted. That column contains a heavily salted hashed password so exposing it isn’t necessarily a disaster, but I like to default to keeping hashes safe.

# 26th September 2024, 9:57 pm / projects, sqlite, plugins, djp, datasette, django

nanodjango. Richard Terry demonstrated this in a lightning talk at DjangoCon US today. It's the latest in a long line of attempts to get Django to work with a single file (I had a go at this problem 15 years ago with djng) but this one is really compelling.

I tried nanodjango out just now and it works exactly as advertised. First install it like this:

pip install nanodjango

Create a counter.py file:

from django.db import models
from nanodjango import Django

app = Django()

@app.admin # Registers with the Django admin
class CountLog(models.Model):
    timestamp = models.DateTimeField(auto_now_add=True)

@app.route("/")
def count(request):
    CountLog.objects.create()
    return f"<p>Number of page loads: {CountLog.objects.count()}</p>"

Then run it like this (it will run migrations and create a superuser as part of that first run):

nanodjango run counter.py

That's it! This gave me a fully configured Django application with models, migrations, the Django Admin configured and a bunch of other goodies such as Django Ninja for API endpoints.

Here's the full documentation.

# 24th September 2024, 4:08 pm / radiac, django, python

UV — I am (somewhat) sold (via) Oliver Andrich's detailed notes on adopting uv. Oliver has some pretty specific requirements:

I need to have various Python versions installed locally to test my work and my personal projects. Ranging from Python 3.8 to 3.13. [...] I also require decent dependency management in my projects that goes beyond manually editing a pyproject.toml file. Likewise, I am way too accustomed to poetry add .... And I run a number of Python-based tools --- djhtml, poetry, ipython, llm, mkdocs, pre-commit, tox, ...

He's braver than I am!

I started by removing all Python installations, pyenv, pipx and Homebrew from my machine. Rendering me unable to do my work.

Here's a neat trick: first install a specific Python version with uv like this:

uv python install 3.11

Then create an alias to run it like this:

alias python3.11 'uv run --python=3.11 python3'

And install standalone tools with optional extra dependencies like this (a replacement for pipx and pipx inject):

uv tool install --python=3.12 --with mkdocs-material mkdocs

Oliver also links to Anže Pečar's handy guide on using UV with Django.

# 15th September 2024, 2:54 pm / uv, astral, packaging, python, django

New Django {% querystring %} template tag. Django 5.1 came out last week and includes a neat new template tag which solves a problem I've faced a bunch of times in the past.

{% querystring color="red" size="S" %}

Adds ?color=red&size=S to the current URL - keeping any other existing parameters and replacing the current value for color or size if it's already set.

{% querystring color=None %}

Removes the ?color= parameter if it is currently set.

If the value passed is a list it will append ?color=red&color=blue for as many items as exist in the list.

You can access values in variables and you can also assign the result to a new template variable rather than outputting it directly to the page:

{% querystring page=page.next_page_number as next_page %}

Other things that caught my eye in Django 5.1:

• PostgreSQL connection pools.
• The new LoginRequiredMiddleware for making every page in an application require login.
• The SQLite database backend now accepts init_command for settings things like PRAGMA cache_size=2000 on new connections.
• SQLite can also be passed "transaction_mode": "IMMEDIATE" to configure the behaviour of transactions.

# 13th August 2024, 6:03 pm / urls, sqlite, postgresql, django

Announcing our DjangoCon US 2024 Talks! I'm speaking at DjangoCon in Durham, NC in September.

My accepted talk title was How to design and implement extensible software with plugins. Here's my abstract:

Plugins offer a powerful way to extend software packages. Tools that support a plugin architecture include WordPress, Jupyter, VS Code and pytest - each of which benefits from an enormous array of plugins adding all kinds of new features and expanded capabilities.

Adding plugin support to an open source project can greatly reduce the friction involved in attracting new contributors. Users can work independently and even package and publish their work without needing to directly coordinate with the project's core maintainers. As a maintainer this means you can wake up one morning and your software grew new features without you even having to review a pull request!

There's one catch: information on how to design and implement plugin support for a project is scarce.

I now have three major open source projects that support plugins, with over 200 plugins published across those projects. I'll talk about everything I've learned along the way: when and how to use plugins, how to design plugin hooks and how to ensure your plugin authors have as good an experience as possible.

I'm going to be talking about what I've learned integrating Pluggy with Datasette, LLM and sqlite-utils. I've been looking for an excuse to turn this knowledge into a talk for ages, very excited to get to do it at DjangoCon!

# 17th July 2024, 3:20 am / djangocon, python, plugins, django, speaking, sqlite-utils, llm, datasette

Django: Test for pending migrations (via) Neat recipe from Adam Johnson for adding an automated test to your Django test suite that runs manage.py makemigrations --check to ensure you don't accidentally land code that deploys with a missing migration and crashes your site. I've made this mistake before myself so I'll be adding this to my projects.

# 28th June 2024, 3:23 pm / adam-johnson, django

Optimal SQLite settings for Django (via) Giovanni Collazo put the work in to figure out settings to make SQLite work well for production Django workloads. WAL mode and a busy_timeout of 5000 make sense, but the most interesting recommendation here is "transaction_mode": "IMMEDIATE" to avoid locking errors when a transaction is upgraded to a write transaction.

Giovanni's configuration depends on the new "init_command" support for SQLite PRAGMA options introduced in Django 5.1alpha.

# 13th June 2024, 5:04 am / sqlite, django

Django Enhancement Proposal 14: Background Workers. Jake Howard's DEP has been approved and is moving into the implementation stage.

Django doesn't have a first-party solution for long-running tasks, however the ecosystem is filled with incredibly popular frameworks, all of which interact with Django in slightly different ways. Other frameworks such as Laravel have background workers built-in, allowing them to push tasks into the background to be processed at a later date, without requiring the end user to wait for them to occur. [...]

This proposal sets out to provide an interface and base implementation for long-running background tasks in Django.

Jake has an illustrative reference implementation called django-tasks.

# 31st May 2024, 8:44 am / django

Enforcing conventions in Django projects with introspection (via) Luke Plant shows how to use the Django system checks framework to introspect models on startup and warn if a DateTime or Date model field has been added that doesn’t conform to a specific naming convention.

Luke also proposes “*_at” as a convention for DateTimes, contrasting with “*_on” or “*_date” (I prefer the latter) for Dates.

# 3rd April 2024, 2:58 pm / lukeplant, django

Talking about Django’s history and future on Django Chat (via) Django co-creator Jacob Kaplan-Moss sat down with the Django Chat podcast team to talk about Django’s history, his recent return to the Django Software Foundation board and what he hopes to achieve there.

Here’s his post about it, where he used Whisper and Claude to extract some of his own highlights from the conversation.

# 21st March 2024, 12:42 am / jacob-kaplan-moss, python, django, podcasts, dsf

DiskCache (via) Grant Jenks built DiskCache as an alternative caching backend for Django (also usable without Django), using a SQLite database on disk. The performance numbers are impressive—it even beats memcached in microbenchmarks, due to avoiding the need to access the network.

The source code (particularly in core.py) is a great case-study in SQLite performance optimization, after five years of iteration on making it all run as fast as possible.

# 19th March 2024, 3:43 pm / sqlite, django, python, performance

Django Chat: Datasette, LLMs, and Django. I’m the guest on the latest episode of the Django Chat podcast. We talked about Datasette, LLMs, the New York Times OpenAI lawsuit, the Python Software Foundation and all sorts of other topics.

# 24th January 2024, 8:41 pm / llms, generative-ai, ai, psf, django, podcasts

DSF calls for applicants for a Django Fellow. The Django Software Foundation employs contractors to manage code reviews and releases, responsibly handle security issues, coach new contributors, triage tickets and more.

This is the Django Fellows program, which is now ten years old and has proven enormously impactful.

Mariusz Felisiak is moving on after five years and the DSF are calling for new applicants, open to anywhere in the world.

# 20th January 2024, 8:35 am / open-source, django, dsf

Database generated columns: GeoDjango & PostGIS. Paolo Melchiorre advocated for the inclusion of generated columns, one of the biggest features in Django 5.0. Here he provides a detailed tutorial showing how they can be used with PostGIS to create database tables that offer columns such as geohash that are automatically calculated from other columns in the table.

# 11th December 2023, 7:14 pm / postgresql, gis, django

Database Migrations. Vadim Kravcenko provides a useful, in-depth description of the less obvious challenges of applying database migrations successfully. Vadim uses and likes Django’s migrations (as do I) but notes that running them at scale still involves a number of thorny challenges.

The biggest of these, which I’ve encountered myself multiple times, is that if you want truly zero downtime deploys you can’t guarantee that your schema migrations will be deployed at the exact same instant as changes you make to your application code.

This means all migrations need to be forward-compatible: you need to apply a schema change in a way that your existing code will continue to work error-free, then ship the related code change as a separate operation.

Vadim describes what this looks like in detail for a number of common operations: adding a field, removing a field and changing a field that has associated business logic implications. He also discusses the importance of knowing when to deploy a dual-write strategy.

# 1st October 2023, 11:55 pm / django, migrations, databases, ops, zero-downtime