Jinja2 form rendering for the admin

[Joey Wilhelm]

I know that Jinja2 vs DTL rendering can be a contentious issue at times, so I want to start from the outset saying that I am not proposing re-implementing the entire admin in Jinja2 templates!

However, that said, I believe that it is not only possible, but in fact easy, to get forms to render using the Jinja2 engine in the admin. I've actually just managed this on my current project at work, and I wanted to see what thoughts would be for inclusion in core.

According to the documentation[1], "...django.contrib.admin doesn’t include Jinja2 templates for its widgets due to their usage of Django template tags."

After some digging, though, it appears that the "spaceless" tag is the only one in use which is not readily available in Jinja2. And this is only used in django/contrib/admin/templates/admin/widgets/related_widget_wrapper.html.

So I was able to reimplement this template in Jinja2, minus the spaceless tag, and I was off to the races. On a few admin pages with large numbers of inlines, the load time was cut in half or better.

But, of course, there was one more small catch. I had to use the "TemplateSetting" form renderer rather than the "Jinja2" form renderer, because I had no way to alter the Jinja2 environment for the form renderer. The environment I refer to in my settings, however, is pulled almost verbatim from the documentation for the Jinja2 backend[2]. I only had to add one thing: i18n. Which turns out to be fairly simple to do with Jinja2 + Django. I was even able to use the "gettext" and "ngettext" from django.utils.translation.

So what I'm proposing here boils down to a few pieces:

1) Create jinja2 templates for the admin widgets. I already have one of these done, and the others look like it may be possible to simply copy them.

2) Document how to add i18n to the Jinja2 environment

3) Perhaps provide a default environment to Jinja2, providing both static and url, as currently documented in the example Jinja2 environment, along with i18n. This would provide a better out-of-the-box experience for users, including being able to set the FORM_RENDERER to Jinja2, and have the admin Just Work.

So, thoughts? Is this something worth filing a ticket for?

-Joey Wilhelm

[1]: https://docs.djangoproject.com/en/2.0/ref/forms/renderers/#jinja2

[2]: https://docs.djangoproject.com/en/2.0/topics/templates/#django.template.backends.jinja2.Jinja2

[Tim Graham]

I guess it's fine. I see you already created a ticket: https://code.djangoproject.com/ticket/29115.