Fixed #35189 -- Improved admin collapsible fieldsets by using <details> elements.

This work improves the accessibility of the add and change pages in the
admin site by adding <details> and <summary> elements to the collapsible
fieldsets. This has the nice side effect of no longer requiring custom
JavaScript helpers to implement the fieldsets' show/hide capabilities.

Thanks to James Scholes for the accessibility advice, and to Sarah Boyce
and Tom Carrick for reviews.

Co-authored-by: Natalia <124304+nessita@users.noreply.github.com>
Co-authored-by: Sarah Boyce <42296566+sarahboyce@users.noreply.github.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/django/contrib/admin/helpers.py b/django/contrib/admin/helpers.py
index c4613fa24e..a4aa8e40e3 100644
--- a/django/contrib/admin/helpers.py
+++ b/django/contrib/admin/helpers.py
@@ -18,6 +18,7 @@ from django.db.models.fields.related import (
 from django.forms.utils import flatatt
 from django.template.defaultfilters import capfirst, linebreaksbr
 from django.urls import NoReverseMatch, reverse
+from django.utils.functional import cached_property
 from django.utils.html import conditional_escape, format_html
 from django.utils.safestring import mark_safe
 from django.utils.translation import gettext
@@ -116,10 +117,14 @@ class Fieldset:
 
     @property
     def media(self):
-        if "collapse" in self.classes:
-            return forms.Media(js=["admin/js/collapse.js"])
         return forms.Media()
 
+    @cached_property
+    def is_collapsible(self):
+        if any([field in self.fields for field in self.form.errors]):
+            return False
+        return "collapse" in self.classes
+
     def __iter__(self):
         for field in self.fields:
             yield Fieldline(
@@ -438,6 +443,12 @@ class InlineAdminFormSet:
     def forms(self):
         return self.formset.forms
 
+    @cached_property
+    def is_collapsible(self):
+        if any(self.formset.errors):
+            return False
+        return "collapse" in self.classes
+
     def non_form_errors(self):
         return self.formset.non_form_errors()