Add option to choose a specific template engine for Django Admin

[Foucauld Degeorges]

Context:
We have two template engines in our app - one that is permissive with invalid variables (e.g. accessing a property on None), the other one raises on invalid variables.
Django Admin requires the permissive one as it makes use of the fallback mechanic on invalid variables.

But we prefer for all our other renders (views, emails, PDFs) to be strict on invalid variables. So we want our strict template engine to be the default one, and specify a custom one for the admin.

The idea would be an optional property on AdminSite named template_engine, that sets the using argument of all TemplateResponses returned by admin views.

[Natalia Bidart]

Hello Foucauld Degeorges! Thank you for your report and interest in making Django better.

The new feature that you are proposing seems a very specific need arising from a niche use case. I don't think this applies to the broader ecosystem, and Django is a framework designed to offer robust and accurate solutions for common scenarios.

There are posts from, for example, Adam Johnson about being verbose and selective about missing variables in templates, without resorting to multiple engines. See for example:

​https://adamj.eu/tech/2022/03/30/how-to-make-django-error-for-undefined-template-variables/
​https://adamj.eu/tech/2023/08/09/django-perils-string-if-invalid/

Given the above, I'll close the ticket accordingly, but if you disagree, you can consider starting a new conversation on the ​Django Forum, where you'll reach a wider audience and likely get extra feedback. More information in ​the documented guidelines for requesting features.