Readonly callable field is unconditionally wrapped inside <p>...</p>, which might create invalid HTML

[Jacob Rief]

(Pseudo)-Fields in classes inheriting from django.contrib.admin.ModelsAdmin which are callables, must be listed in readonly_fields. This implies that in admin/includes/fieldset.html (line 17) and admin/edit_inline/tabular.html (line 55) the content of this field is wrapped inside a paragraph <p>{{ field.contents }}</p>.

However, a <p>...</p> is not suitable to accept every kind of HTML element. Therefore when using a "callable" field, which renders it's content in HTML, one might get a surprising result.

Since the author of a callable field may wrap it's content into whatever (s)he likes, there should be a way to avoid these wrapping paragraphs.

My proposal is to check if field.contents is safe text, and if so then leave it as-is, or otherwise wrap it into <p>..</p> as we do it right now.

[Tim Graham]

I'm not sure if the proposal is completely backwards-compatible, but the problem seems real.

[Jacob Rief]

Yes, changing this could add a minor backwards compatibility problem; something probably not really noticeable and if, easy to fix.

I looked at the code. We presumably should add another tag to django.contrib.admin.helpers.AdminReadonlyField.init named is_callable which is True for callable fields. Then in the templates, we'd have to add another {% if field.is_callable %} and only wrap the content inside <p>..</p> it that's false.

If this proposal is accepted, I will implement it right now.

[Tim Graham]

I'm not sure. It doesn't seem obviously correct to assume that all callables might have HTML.

[Jacob Rief]

PR ​https://github.com/django/django/pull/7477 to fix this ticket is pending.

[Tim Graham]

Some comments for improvement are on the PR.

[Tim Graham <timograham@…>]

In b3162ca:

Fixed #27386 -- Wrapped admin's readonly fields in <div> rather than <p>.