Django on Enrique Soria

How to display a JSON value in Django admin (when using MySQL)

Tue, 18 Nov 2025 18:24:02 +0100

tldr; here’s a small working example of this: https://github.com/EnriqueSoria/DisplayJsonValueInAdmin

Let’s say that, for some reason, we have a json stored in a TextField or a JSONField (available since Django 3.1) that stores a payload.

class Webhook(models.Model):
 payload = models.TextField() # works also with models.JSONField()
 ... # more fields

Showing the `timestamp` as a `datetime` in the admin list

If we wanted to display the timestamp in the admin list, we could use some of the methods present in this guide. For instance, we could create a method in the admin:

TIL: La caché de `functools.lru_cache` se mantiene entre tests

Tue, 03 Dec 2024 01:01:00 +0100

Asumamos que tenemos una función cacheada con functools.lru_cache:

# utils.py
from functools import lru_cache


SETTINGS = {"DATABASE_NAME": "default"}

@lru_cache
def get_setting(key):
 return SETTINGS[key]

Y un par de tests que comprueban su comportamiento:

# test_utils.py
import pytest

from utils import get_setting


def test_get_database_name():
 global SETTINGS

 assert get_setting("DATABASE_NAME") == "default"


def test_get_modified_database_name_after_modifying_it():
 from utils import SETTINGS

 SETTINGS["DATABASE_NAME"] = "modified"

 assert get_setting("DATABASE_NAME") == "modified"

Si lo ejecutamos comprobaremos que el segundo test falla, ya que devuelve el valor que tenía antes de ser modificado el SETTINGS. Esto es debido a que la caché lru_cache no se limpia entre tests.

TIL: Django relations are not cached in model instance

Tue, 19 Nov 2024 19:34:00 +0100

Evaluating relation multiple times using `.all()` performs `n` queries

Input:

order = Order.objects.first()

with query_debugger("without prefetch"):
 list(order.lines.all())
 list(order.lines.all())
 list(order.lines.all())

Output:

without prefetch: 3 queries

Input:

order = Order.objects.first()

with query_debugger("storing related queryset in a variable"):
 lines = order.lines.all()
 list(lines)
 list(lines)
 list(lines)

Output:

storing related queryset in a variable: 1 queries

Evaluating a prefetched related queryset multiple times using `.all()` doesn’t perform any extra query

Input:

The story of how `ChildSourceListSerializer` became a thing

Mon, 03 Apr 2023 17:07:00 +0100

The story

Once upon a time, there was a Django developer named Sarah who was working on a new API using Django REST Framework. She had a model Movie which had a many-to-many relationship with Genre. Sarah wanted to create an endpoint that returned a list of movies with their associated genres as a list of strings.

Initially, Sarah tried to use a standard ListSerializer to serialize the genres, but she quickly realized that the source attribute of the child serializer was not taken into account when serializing a list of objects. This meant that she was unable to customize the serialization of the child objects based on their source attribute.

Una gran experiència amb l'open source

Sat, 26 Nov 2022 13:20:00 +0100

Lo que ha pasat hui ha sigut increïble.

07:56 AM - El descobriment

Cada dia quan em desperte perd un rato amb el mòbil, mire notificacions, xarxes socials, etc… cosa que no es molt recomanable però ey, com diu Cactus: “ni som perfectes, ni volem ser-ho”.

Mentre perdia el temps mirant mastodon (on em podeu seguir) he trobat un toot recomanant una llibreria per a Django:

Es una llibreria simple, però que afegix un buscador que, personalment, trobe molt a faltar a l’admin de django.

Create mantainable env.sample using django-environ

Tue, 20 Sep 2022 08:00:00 +0200

Keeping your env.sample is a hard task, that’s why I created a way to have it updated automatically:

How-to:

Put every env var with its configuration in a ENV_DEFAULTS variable, in a separate python file named environment_defaults.py (exactly this file name)

# environment_defaults.py
ENV_DEFAULTS = dict(
 VARIABLE_WITH_DEFAULT_VALUE=(str, "default value"),
 VARIABLE_WITHOUT_DEFAULT_VALUE=str,
)

Instantiate Env with ENV_DEFAULTS on your Django settings file

# settings.py
from environ import Env
from environment_defaults import ENV_DEFAULTS

env = Env(**ENV_DEFAULTS)

And ensure you are accessing it using env("VAR_NAME") instead of env.str("VAR_NAME")

Django on Enrique Soria

How to display a JSON value in Django admin (when using MySQL)

Showing the timestamp as a datetime in the admin list

TIL: La caché de `functools.lru_cache` se mantiene entre tests

TIL: Django relations are not cached in model instance

Evaluating relation multiple times using .all() performs n queries

Evaluating a related queryset stored in a variable only performs one query

Evaluating a prefetched related queryset multiple times using .all() doesn’t perform any extra query

The story of how `ChildSourceListSerializer` became a thing

The story

Una gran experiència amb l'open source

07:56 AM - El descobriment

Create mantainable env.sample using django-environ

How-to:

Showing the `timestamp` as a `datetime` in the admin list

Evaluating relation multiple times using `.all()` performs `n` queries

Evaluating a prefetched related queryset multiple times using `.all()` doesn’t perform any extra query