[2.2.x] Fixed #30459 -- Delegated hide/show JS toggle to parent div.

Co-authored-by: Carlton Gibson <carlton.gibson@noumenal.es>

Backport of e286987 from master

django/contrib/admin/static/admin/js/collapse.js

@@ -30,23 +30,26 @@
                 h2.appendChild(document.createTextNode(')'));
             }
         }
-        // Add toggle to anchor tag
-        var toggles = document.querySelectorAll('fieldset.collapse a.collapse-toggle');
+        // Add toggle to hide/show anchor tag
         var toggleFunc = function(ev) {
-            ev.preventDefault();
-            var fieldset = closestElem(this, 'fieldset');
-            if (fieldset.classList.contains('collapsed')) {
-                // Show
-                this.textContent = gettext('Hide');
-                fieldset.classList.remove('collapsed');
-            } else {
-                // Hide
-                this.textContent = gettext('Show');
-                fieldset.classList.add('collapsed');
+            if (ev.target.matches('.collapse-toggle')) {
+                ev.preventDefault();
+                ev.stopPropagation();
+                var fieldset = closestElem(ev.target, 'fieldset');
+                if (fieldset.classList.contains('collapsed')) {
+                    // Show
+                    ev.target.textContent = gettext('Hide');
+                    fieldset.classList.remove('collapsed');
+                } else {
+                    // Hide
+                    ev.target.textContent = gettext('Show');
+                    fieldset.classList.add('collapsed');
+                }
             }
         };
-        for (i = 0; i < toggles.length; i++) {
-            toggles[i].addEventListener('click', toggleFunc);
+        var inlineDivs = document.querySelectorAll('fieldset.module');
+        for (i = 0; i < inlineDivs.length; i++) {
+            inlineDivs[i].addEventListener('click', toggleFunc);
         }
     });
 })();

docs/releases/2.2.2.txt

@@ -9,4 +9,5 @@ Django 2.2.2 fixes several bugs in 2.2.1.
 Bugfixes
 ========
 
-* ...
+* Fixed a regression in Django 2.2 that stopped Show/Hide toggles working on
+  dynamically added admin inlines (:ticket:`30459`).

tests/admin_inlines/admin.py

@@ -3,13 +3,14 @@
 from django.db import models
 
 from .models import (
-    Author, BinaryTree, CapoFamiglia, Chapter, ChildModel1, ChildModel2,
+    Author, BinaryTree, CapoFamiglia, Chapter, Child, ChildModel1, ChildModel2,
     Consigliere, EditablePKBook, ExtraTerrestrial, Fashionista, Holder,
     Holder2, Holder3, Holder4, Inner, Inner2, Inner3, Inner4Stacked,
     Inner4Tabular, NonAutoPKBook, NonAutoPKBookChild, Novel,
     NovelReadonlyChapter, ParentModelWithCustomPk, Poll, Profile,
     ProfileCollection, Question, ReadOnlyInline, ShoppingWeakness, Sighting,
-    SomeChildModel, SomeParentModel, SottoCapo, Title, TitleCollection,
+    SomeChildModel, SomeParentModel, SottoCapo, Teacher, Title,
+    TitleCollection,
 )
 
 site = admin.AdminSite(name="admin")
@@ -235,6 +236,18 @@ class SomeChildModelInline(admin.TabularInline):
     readonly_fields = ('readonly_field',)
 
 
+class StudentInline(admin.StackedInline):
+    model = Child
+    extra = 1
+    fieldsets = [
+        ('Name', {'fields': ('name',), 'classes': ('collapse',)}),
+    ]
+
+
+class TeacherAdmin(admin.ModelAdmin):
+    inlines = [StudentInline]
+
+
 site.register(TitleCollection, inlines=[TitleInline])
 # Test bug #12561 and #12778
 # only ModelAdmin media
@@ -257,3 +270,4 @@ class SomeChildModelInline(admin.TabularInline):
 site.register(ExtraTerrestrial, inlines=[SightingInline])
 site.register(SomeParentModel, inlines=[SomeChildModelInline])
 site.register([Question, Inner4Stacked, Inner4Tabular])
+site.register(Teacher, TeacherAdmin)

tests/admin_inlines/tests.py

@@ -1024,3 +1024,21 @@ def test_collapsed_inlines(self):
             self.wait_until_visible(field_name)
             hide_links[hide_index].click()
             self.wait_until_invisible(field_name)
+
+    def test_added_stacked_inline_with_collapsed_fields(self):
+        self.admin_login(username='super', password='secret')
+        self.selenium.get(self.live_server_url + reverse('admin:admin_inlines_teacher_add'))
+        self.selenium.find_element_by_link_text('Add another Child').click()
+        test_fields = ['#id_child_set-0-name', '#id_child_set-1-name']
+        show_links = self.selenium.find_elements_by_link_text('SHOW')
+        self.assertEqual(len(show_links), 2)
+        for show_index, field_name in enumerate(test_fields, 0):
+            self.wait_until_invisible(field_name)
+            show_links[show_index].click()
+            self.wait_until_visible(field_name)
+        hide_links = self.selenium.find_elements_by_link_text('HIDE')
+        self.assertEqual(len(hide_links), 2)
+        for hide_index, field_name in enumerate(test_fields, 0):
+            self.wait_until_visible(field_name)
+            hide_links[hide_index].click()
+            self.wait_until_invisible(field_name)