[2.1.x] Fixed #29930 -- Allowed editing in admin with view-only inlines.

Co-authored-by: Tim Graham <timograham@gmail.com>
Backport of 8245c99ee6032c2748ba46583d8cab15b2f9438e from master

4 files changed, 116 insertions, 1 deletions

diff --git a/django/contrib/admin/options.py b/django/contrib/admin/options.py
index d0948359ab..ddaf130584 100644
--- a/django/contrib/admin/options.py
+++ b/django/contrib/admin/options.py
@@ -1948,7 +1948,24 @@ class ModelAdmin(BaseModelAdmin):
                     'files': request.FILES,
                     'save_as_new': '_saveasnew' in request.POST
                 })
-            formsets.append(FormSet(**formset_params))
+            formset = FormSet(**formset_params)
+
+            def user_deleted_form(request, obj, formset, index):
+                """Return whether or not the user deleted the form."""
+                return (
+                    inline.has_delete_permission(request, obj) and
+                    '{}-{}-DELETE'.format(formset.prefix, index) in request.POST
+                )
+
+            # Bypass validation of each view-only inline form (since the form's
+            # data won't be in request.POST), unless the form was deleted.
+            if not inline.has_change_permission(request, obj):
+                for index, form in enumerate(formset.initial_forms):
+                    if user_deleted_form(request, obj, formset, index):
+                        continue
+                    form._errors = {}
+                    form.cleaned_data = form.initial
+            formsets.append(formset)
             inline_instances.append(inline)
         return formsets, inline_instances
 
diff --git a/docs/releases/2.1.4.txt b/docs/releases/2.1.4.txt
index 8ba457846e..6d0c3dce46 100644
--- a/docs/releases/2.1.4.txt
+++ b/docs/releases/2.1.4.txt
@@ -22,3 +22,7 @@ Bugfixes
 
 * Fixed admin view-only change form crash when using
   ``ModelAdmin.prepopulated_fields`` (:ticket:`29929`).
+
+* Fixed "Please correct the errors below" error message when editing an object
+  in the admin if the user only has the "view" permission on inlines
+  (:ticket:`29930`).
diff --git a/tests/admin_views/tests.py b/tests/admin_views/tests.py
index 2d1e58aa26..a94bbbccfc 100644
--- a/tests/admin_views/tests.py
+++ b/tests/admin_views/tests.py
@@ -1918,6 +1918,96 @@ class AdminViewPermissionsTest(TestCase):
         new_article = Article.objects.latest('id')
         self.assertRedirects(post, reverse('admin:admin_views_article_change', args=(new_article.pk,)))
 
+    def test_change_view_with_view_only_inlines(self):
+        """
+        User with change permission to a section but view-only for inlines.
+        """
+        self.viewuser.user_permissions.add(get_perm(Section, get_permission_codename('change', Section._meta)))
+        self.client.force_login(self.viewuser)
+        # GET shows inlines.
+        response = self.client.get(reverse('admin:admin_views_section_change', args=(self.s1.pk,)))
+        self.assertEqual(len(response.context['inline_admin_formsets']), 1)
+        formset = response.context['inline_admin_formsets'][0]
+        self.assertEqual(len(formset.forms), 3)
+        # Valid POST changes the name.
+        data = {
+            'name': 'Can edit name with view-only inlines',
+            'article_set-TOTAL_FORMS': 3,
+            'article_set-INITIAL_FORMS': 3
+        }
+        response = self.client.post(reverse('admin:admin_views_section_change', args=(self.s1.pk,)), data)
+        self.assertRedirects(response, reverse('admin:admin_views_section_changelist'))
+        self.assertEqual(Section.objects.get(pk=self.s1.pk).name, data['name'])
+        # Invalid POST reshows inlines.
+        del data['name']
+        response = self.client.post(reverse('admin:admin_views_section_change', args=(self.s1.pk,)), data)
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(len(response.context['inline_admin_formsets']), 1)
+        formset = response.context['inline_admin_formsets'][0]
+        self.assertEqual(len(formset.forms), 3)
+
+    def test_change_view_with_view_and_add_inlines(self):
+        """User has view and add permissions on the inline model."""
+        self.viewuser.user_permissions.add(get_perm(Section, get_permission_codename('change', Section._meta)))
+        self.viewuser.user_permissions.add(get_perm(Article, get_permission_codename('add', Article._meta)))
+        self.client.force_login(self.viewuser)
+        # GET shows inlines.
+        response = self.client.get(reverse('admin:admin_views_section_change', args=(self.s1.pk,)))
+        self.assertEqual(len(response.context['inline_admin_formsets']), 1)
+        formset = response.context['inline_admin_formsets'][0]
+        self.assertEqual(len(formset.forms), 6)
+        # Valid POST creates a new article.
+        data = {
+            'name': 'Can edit name with view-only inlines',
+            'article_set-TOTAL_FORMS': 6,
+            'article_set-INITIAL_FORMS': 3,
+            'article_set-3-id': [''],
+            'article_set-3-title': ['A title'],
+            'article_set-3-content': ['Added content'],
+            'article_set-3-date_0': ['2008-3-18'],
+            'article_set-3-date_1': ['11:54:58'],
+            'article_set-3-section': [str(self.s1.pk)],
+        }
+        response = self.client.post(reverse('admin:admin_views_section_change', args=(self.s1.pk,)), data)
+        self.assertRedirects(response, reverse('admin:admin_views_section_changelist'))
+        self.assertEqual(Section.objects.get(pk=self.s1.pk).name, data['name'])
+        self.assertEqual(Article.objects.count(), 4)
+        # Invalid POST reshows inlines.
+        del data['name']
+        response = self.client.post(reverse('admin:admin_views_section_change', args=(self.s1.pk,)), data)
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(len(response.context['inline_admin_formsets']), 1)
+        formset = response.context['inline_admin_formsets'][0]
+        self.assertEqual(len(formset.forms), 6)
+
+    def test_change_view_with_view_and_delete_inlines(self):
+        """User has view and delete permissions on the inline model."""
+        self.viewuser.user_permissions.add(get_perm(Section, get_permission_codename('change', Section._meta)))
+        self.client.force_login(self.viewuser)
+        data = {
+            'name': 'Name is required.',
+            'article_set-TOTAL_FORMS': 6,
+            'article_set-INITIAL_FORMS': 3,
+            'article_set-0-id': [str(self.a1.pk)],
+            'article_set-0-DELETE': ['on'],
+        }
+        # Inline POST details are ignored without delete permission.
+        response = self.client.post(reverse('admin:admin_views_section_change', args=(self.s1.pk,)), data)
+        self.assertRedirects(response, reverse('admin:admin_views_section_changelist'))
+        self.assertEqual(Article.objects.count(), 3)
+        # Deletion successful when delete permission is added.
+        self.viewuser.user_permissions.add(get_perm(Article, get_permission_codename('delete', Article._meta)))
+        data = {
+            'name': 'Name is required.',
+            'article_set-TOTAL_FORMS': 6,
+            'article_set-INITIAL_FORMS': 3,
+            'article_set-0-id': [str(self.a1.pk)],
+            'article_set-0-DELETE': ['on'],
+        }
+        response = self.client.post(reverse('admin:admin_views_section_change', args=(self.s1.pk,)), data)
+        self.assertRedirects(response, reverse('admin:admin_views_section_changelist'))
+        self.assertEqual(Article.objects.count(), 2)
+
     def test_delete_view(self):
         """Delete view should restrict access and actually delete items."""
         delete_dict = {'post': 'yes'}
diff --git a/tests/modeladmin/test_has_add_permission_obj_deprecation.py b/tests/modeladmin/test_has_add_permission_obj_deprecation.py
index f5489a41db..c85b80da5f 100644
--- a/tests/modeladmin/test_has_add_permission_obj_deprecation.py
+++ b/tests/modeladmin/test_has_add_permission_obj_deprecation.py
@@ -86,6 +86,10 @@ class ModelAdminTests(TestCase):
         self.song = Song.objects.create(name='test', band=self.band)
         self.site = AdminSite()
         self.request = MockRequest()
+        self.request.POST = {
+            'song_set-TOTAL_FORMS': 4,
+            'song_set-INITIAL_FORMS': 1,
+        }
         self.request.user = self.MockAddUser()
         self.ma = BandAdmin(Band, self.site)