Overriding template blocks without copy/pasting entire template files

[Josh Smeaton]

Something that has bugged me for awhile is the requirement to copy and paste an entire template when you would just like to override a single block. This arises mostly when overriding admin templates, like `admin/base.html`.

In my ideal world, I'd be able to do something like this:

    # myapp/templates/admin/base.html
    {% override "admin/base.html" %}
    {% block footer %}this site is restricted, blah blah legal text blah{% endblock %}

And then the template loading system would find the next `admin/base.html` in the chain and use my overrides.

There is prior art too. https://pypi.org/project/django-apptemplates/ allows you to override a template from a specific app using this syntax:

    # myapp/templates/admin/base.html
    {% extends "admin:admin/base.html" %}
    {% block footer %}this site is restricted, blah blah legal text blah{% endblock %}

I think this kind of functionality should be included within Django itself. If others agree, should there be a new name such as override, or would overloading extends be good enough?

[Carlton Gibson]

Hi Josh.

This was added in Django 1.9 here https://github.com/django/django/commit/fc2147152637e21bc73f991b50fa06254af02739

It leverages the extends tag, re-using the same template name:

    # myapp/templates/admin/base.html
    {% extends "admin/base.html" %}


    {% block footer %}this site is restricted, blah blah legal text blah{% endblock %}

So as long as myapp/templates are loaded before contrib.admin's then it you should see the result you're after.

#15053 references django-overextends as the influence.

Kind Regards,

Carlton

[Josh Smeaton]

Changed 5 years ago by Preston Timmons

🤦‍♀️

Thanks Carlton - I guess it has *only* been 5 years though :)

[Josh Smeaton]

Upon reflection, would you agree that this should be documented a little better? The release notes at the time had a vague deprecation note about `supports_recursion` being removed, and the main docs https://docs.djangoproject.com/en/3.0/ref/templates/builtins/#std:templatetag-extends have no such explanation about recursive inheritance either.

I pointed out this thread to a few people in my team, and none of them were aware of this fix/feature, and they were all using 3rd party packages for support.

Funnily enough, https://docs.djangoproject.com/en/3.0/ref/contrib/admin/#overriding-vs-replacing-an-admin-template seems to suggest this was always possible, so I'm quite confused.

[Carlton Gibson]

Yes! Absolutely. There's even a ticket for that: https://code.djangoproject.com/ticket/29336

There was a PR, but we couldn't get it down to size... (Review)

[Arvind Nedumaran]

Could you elaborate on how this is different from extending a base template and re-defining the necessary blocks?

#base.html
{% block title %}{{ section.title }}{% endblock %}
..... 

{% extends "base.html" %}
{% block title %} My custom title that isn't section.title {% endblock %}
....

This much is already possible right?

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[Florian Apolloner]

If you look at the mails beyond the first one, you will see that Josh & Carlton already came to that conlusion ;)

On Tuesday, June 16, 2020 at 2:16:31 PM UTC+2, Arvind Nedumaran wrote:

Could you elaborate on how this is different from extending a base template and re-defining the necessary blocks?

#base.html
{% block title %}{{ section.title }}{% endblock %}
..... 

{% extends "base.html" %}
{% block title %} My custom title that isn't section.title {% endblock %}
....

This much is already possible right?

On Tue, Jun 16, 2020 at 10:34 AM Josh Smeaton <josh....@gmail.com> wrote:

Something that has bugged me for awhile is the requirement to copy and paste an entire template when you would just like to override a single block. This arises mostly when overriding admin templates, like `admin/base.html`.

In my ideal world, I'd be able to do something like this:

    # myapp/templates/admin/base.html
    {% override "admin/base.html" %}
    {% block footer %}this site is restricted, blah blah legal text blah{% endblock %}

And then the template loading system would find the next `admin/base.html` in the chain and use my overrides.

There is prior art too. https://pypi.org/project/django-apptemplates/ allows you to override a template from a specific app using this syntax:

    # myapp/templates/admin/base.html
    {% extends "admin:admin/base.html" %}
    {% block footer %}this site is restricted, blah blah legal text blah{% endblock %}

I think this kind of functionality should be included within Django itself. If others agree, should there be a new name such as override, or would overloading extends be good enough?

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[Arvind Nedumaran]

Something must be faulty with my email delivery I suppose. I sent that email a good 8 hours ago. :)

Onward,

Arvind

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Sent: Tuesday, June 16, 2020 6:46:45 PM
To: Django developers (Contributions to Django itself) <django-d...@googlegroups.com>
Subject: Re: Overriding template blocks without copy/pasting entire template files

 

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[Florian Apolloner]

Ah, might be that you got hold up in a moderation queue or similar. Google groups is weird sometimes -- sorry!

To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/89b8d89a-d7e4-44fa-a5b8-cb8e1c910785o%40googlegroups.com.

[Arvind Nedumaran]

No worries 👍

Sent from Outlook Mobile

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From: django-d...@googlegroups.com <django-d...@googlegroups.com> on behalf of Florian Apolloner <f.apo...@gmail.com>

Sent: Tuesday, June 16, 2020 7:40:56 PM

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