Comments on: Recursion in Django templates

By: w0manpower.com

w0manpower.com — Sat, 03 Sep 2011 10:42:00 +0000

This still works like a charm years later, I also find it more elegant than doing it in the view, even though we might encounter performance issues.
It’s a template that isn’t used that much on the site anyway.
I have a suggestion to make the rendered code more beautiful and avoid having empty blocks when the node has no children.
Put a if test before the include block {% include filename %} or you could also put it at the beginning of the template, so it doesn’t render with nothing inside.

By: Gevious

Gevious — Tue, 16 Aug 2011 12:04:51 +0000

Thanks for this snippet. Works beautifully (In production too

By: Izkata

Izkata — Mon, 25 Jul 2011 16:25:19 +0000

Aaaand three and a half years later, this trick still works as expected, while include with a constant still causes crashing.

By: Andrew Ash

Andrew Ash — Wed, 27 Oct 2010 07:17:00 +0000

Jérémie, I’m having this exact same issue while trying to get threaded-comments[1] rendering working.

Other directions I’ve been going are to integrate a “recursive_include” into my template tags based on the function at this bug request [2]. That seemed to cause the same problems, so I’m going in a new direction based on [3], which is an intricate dance between template and view to create the final template.

You wouldn’t think getting threaded-comments to actually display in a nested structure would be this difficult!

Have you made progress on the issue?

[1] http://github.com/ericflo/django-threadedcomments
[2] http://code.djangoproject.com/ticket/3544
[3] http://www.elfsternberg.com/2009/05/18/template-recursion-in-django-with-treebeard/

By: Jérémie

Jérémie — Fri, 02 Jul 2010 10:13:04 +0000

Hi,

This is exactly what I need, but I can’t make it work…

I put the code in a template which I included in my main template, the first include is fine, but it doesn’t go further.
It react like if “post” from “{% for post in thread %} ” is empty (but it’s not) and doesn’t go inside the loop.

Does anybody have this kind of trouble?

thanks.

By: Richard

Richard — Mon, 10 May 2010 21:22:36 +0000

Awesome work. Was so proud of my recursion in the view and got stuck on the rendering of it in the template. Can’t believe that you have to assign the filename to a variable but it works just like you said. Thanks, you’re a legend!

PS! I’m using it on a production system but just for admin/cms stuff, so I guess there’s no real harm there. Wanted to have a menu using this (one of those nice superfish-style dropdown menus), but I suspect that that would REALLY kill the server (having to resolve this recursion on every single page call).

By: admin

admin — Thu, 25 Feb 2010 21:42:44 +0000

I would now say it’s mainly problematic since it relies on an implementation detail in the Django template language. There’s no guarantee this might not stop working in a new version.

As for performance issue, I was probably too alarmist, especially now that Django actually can cache templates in memory once compiled. So you probably shouldn’t worry.

But still, if you do want to go after performance, and you are rendering out a forum thread with a huge number of branches and nodes, it’ll sure be faster to set something like an indentation-level attribute in your python code.

By: rennat

rennat — Thu, 25 Feb 2010 19:20:05 +0000

Ok so there’s some cases where I really want to use this in production. (like dynamic nested nav) because it seems like an elegant solution from the way it’s written.

Is this a really bad idea or just not a good idea for a million-uniques-a-day site?

By: Brandon

Brandon — Tue, 24 Mar 2009 04:17:24 +0000

How do you actually implement this in the main template? I’ve tried running this code as an include, and copy/pasted into my main template and handing it a set of categories:

{% for category in categories %}
{{ category.name }}
{% with “list.html” as filename %}
{% with category.category_set.all as category %}
{% include filename %}
{% endwith %}
{% endwith %}
{% endfor %}

This causes the built-in server to completely shut down without an error. What am I doing wrong?

By: Ivan

Ivan — Mon, 06 Oct 2008 20:56:59 +0000

Super cool man…
I was just wondering why recursion doesn’t work… in a reply-to-a-reply rendering template of mine

Why not use in production?
What could poooooosibly ever go wrong with a recursive call