python 17 lines · 4 steps

Busting template fragment caches in Django

A signal receiver clears cached template fragments whenever an Article is saved or deleted.

Explained by highlit
Django Intermediate caching signals cache-invalidation template-fragments
1from django.core.cache import cache
2from django.core.cache.utils import make_template_fragment_key
3from django.db.models.signals import post_save, post_delete
4from django.dispatch import receiver
5 
6from .models import Article
7 
8 
9@receiver(post_save, sender=Article)
10@receiver(post_delete, sender=Article)
11def invalidate_article_fragments(sender, instance, **kwargs):
12 keys = [
13 make_template_fragment_key("article_detail", [instance.pk]),
14 make_template_fragment_key("article_sidebar", [instance.category_id]),
15 make_template_fragment_key("article_list"),
16 ]
17 cache.delete_many(keys)
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Signals let you react to model lifecycle events without touching every save site.
  2. 2Template fragment keys are reconstructible from the same arguments used in the template, so you can target exactly what to invalidate.
  3. 3Deleting stale cache entries on write keeps cached HTML consistent with the database.

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