Simon Willison’s Weblog

13th August 2024 - Link Blog

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.