UI improvements when deleting objects.

Shows nested child objects that will be deleted when deleting a single object or multiple objects.

Includes some hacky tests for NestedObjects in the example app.

djadmin2/actions.py

@@ -1,6 +1,7 @@
 from django.contrib import messages
 from django.core.exceptions import PermissionDenied
 from django.template.response import TemplateResponse
+from django.utils.encoding import force_text
 from django.utils.text import capfirst
 
 from . import utils
@@ -51,9 +52,19 @@ def delete_selected(request, queryset):
         # render a template asking for their confirmation.
         if has_permission:
             template = 'admin2/bootstrap/delete_selected_confirmation.html'
+
+            def _format_callback(obj):
+                opts = obj._meta
+                return '%s: %s' % (force_text(capfirst(opts.verbose_name)),
+                                   force_text(obj))
+
+            collector = utils.NestedObjects(using=None)
+            collector.collect(queryset)
+
             context = {
                 'queryset': queryset,
-                'objects_name': objects_name
+                'objects_name': objects_name,
+                'deletable_objects': collector.nested(_format_callback),
             }
             return TemplateResponse(request, template, context)
         else:

djadmin2/templates/admin2/bootstrap/delete_selected_confirmation.html

@@ -1,13 +1,16 @@
 {% extends "admin2/bootstrap/base.html" %}
 {% load i18n %}
+
+{% block title %}Are you sure?{% endblock %}
+
+{% block page_title %}Are you sure?{% endblock %}
+
 {% block content %}
 
-<p>{% blocktrans with objects_name=objects_name %}Are you sure you want to delete the selected {{ objects_name }}?{% endblocktrans %}</p>
+<p>{% blocktrans with objects_name=objects_name %}Are you sure you want to delete the selected {{ objects_name }}?  All of the following items will be deleted:{% endblocktrans %}</p>
 
 <ul>
-    {% for item in queryset %}
-    <li>{{ item }}</li>
-    {% endfor %}
+    {{ deletable_objects|unordered_list }}
 </ul>
 
 <form method="post">
@@ -15,9 +18,9 @@
     <input type="hidden" name="confirmed" value="yes" />
     <input type="hidden" name="action" value="delete_selected" />
     {% for item in queryset %}
-    <input type="hidden" name="selected_model_pk" value="{{ item.pk }}" />
+        <input type="hidden" name="selected_model_pk" value="{{ item.pk }}" />
     {% endfor %}
-    <input type="submit"/>
+    <button class="btn btn-small btn-danger" type="submit">{% trans "Yes, I'm sure" %}</button>
 </form>
 
 {% endblock content %}

djadmin2/templates/admin2/bootstrap/model_confirm_delete.html

@@ -14,14 +14,17 @@
 {% endblock %}
 
 {% block content %}
-<p>{% blocktrans with model_name=model_name object=object %}Are you sure you want to delete the {{ model_name }} "{{ object }}"? All of the following related items will be deleted:{% endblocktrans %}</p>
 
-TODO
+<p>{% blocktrans with model_name=model_name object=object %}Are you sure you want to delete the {{ model_name }} "{{ object }}"? All of the following items will be deleted:{% endblocktrans %}</p>
+
+<ul>
+	{{ deletable_objects|unordered_list }}
+</ul>
 
 <form method="post">
     {% csrf_token %}
     {{ form.as_p }}
-    <input type="submit"/>
+    <button class="btn btn-small btn-danger" type="submit">{% trans "Yes, I'm sure" %}</button>
 </form>
 
 {% endblock content %}

djadmin2/utils.py

@@ -1,3 +1,6 @@
+from django.db.models.deletion import Collector
+
+
 def model_options(model):
     """
     Wrapper for accessing model._meta. If this access point changes in core
@@ -34,4 +37,65 @@ def model_app_label(obj):
     """
     Returns the app label of a model instance or class.
     """
-    return model_options(obj).app_label    
+    return model_options(obj).app_label    
+
+
+# Taken from the Django core.
+# https://github.com/django/django/blob/1.5.1/django/contrib/admin/util.py#L144
+class NestedObjects(Collector):
+    def __init__(self, *args, **kwargs):
+        super(NestedObjects, self).__init__(*args, **kwargs)
+        self.edges = {} # {from_instance: [to_instances]}
+        self.protected = set()
+
+    def add_edge(self, source, target):
+        self.edges.setdefault(source, []).append(target)
+
+    def collect(self, objs, source_attr=None, **kwargs):
+        for obj in objs:
+            if source_attr:
+                self.add_edge(getattr(obj, source_attr), obj)
+            else:
+                self.add_edge(None, obj)
+        try:
+            return super(NestedObjects, self).collect(
+                objs, source_attr=source_attr, **kwargs)
+        except models.ProtectedError as e:
+            self.protected.update(e.protected_objects)
+
+    def related_objects(self, related, objs):
+        qs = super(NestedObjects, self).related_objects(related, objs)
+        return qs.select_related(related.field.name)
+
+    def _nested(self, obj, seen, format_callback):
+        if obj in seen:
+            return []
+        seen.add(obj)
+        children = []
+        for child in self.edges.get(obj, ()):
+            children.extend(self._nested(child, seen, format_callback))
+        if format_callback:
+            ret = [format_callback(obj)]
+        else:
+            ret = [obj]
+        if children:
+            ret.append(children)
+        return ret
+
+    def nested(self, format_callback=None):
+        """
+        Return the graph as a nested list.
+
+        """
+        seen = set()
+        roots = []
+        for root in self.edges.get(None, ()):
+            roots.extend(self._nested(root, seen, format_callback))
+        return roots
+
+    def can_fast_delete(self, *args, **kwargs):
+        """
+        We always want to load the objects into memory so that we can display
+        them to the user in confirm page.
+        """
+        return False

djadmin2/views.py

@@ -1,10 +1,13 @@
 from django.core.urlresolvers import reverse
 from django.http import HttpResponseRedirect
+from django.utils.encoding import force_text
+from django.utils.text import capfirst
 from django.views import generic
 
 import extra_views
 
 from . import permissions
+from .utils import NestedObjects
 from .viewmixins import Admin2Mixin, AdminModel2Mixin, Admin2ModelFormMixin
 
 
@@ -111,3 +114,18 @@ class ModelDeleteView(AdminModel2Mixin, generic.DeleteView):
     permission_classes = (
         permissions.IsStaffPermission,
         permissions.ModelDeletePermission)
+
+    def get_context_data(self, **kwargs):
+        context = super(ModelDeleteView, self).get_context_data(**kwargs)
+
+        def _format_callback(obj):
+            opts = obj._meta
+            return '%s: %s' % (force_text(capfirst(opts.verbose_name)),
+                               force_text(obj))
+
+        collector = NestedObjects(using=None)
+        collector.collect([self.get_object()])
+        context.update({
+            'deletable_objects': collector.nested(_format_callback)
+        })
+        return context

example/blog/models.py

@@ -1,4 +1,6 @@
 from django.db import models
+from django.utils import six
+from django.utils.encoding import python_2_unicode_compatible
 
 
 class Post(models.Model):
@@ -15,3 +17,34 @@ class Comment(models.Model):
 
     def __unicode__(self):
         return self.body
+
+
+#### Models needed for testing NestedObjects
+
+@python_2_unicode_compatible
+class Count(models.Model):
+    num = models.PositiveSmallIntegerField()
+    parent = models.ForeignKey('self', null=True)
+
+    def __str__(self):
+        return six.text_type(self.num)
+
+
+class Event(models.Model):
+    date = models.DateTimeField(auto_now_add=True)
+
+
+class Location(models.Model):
+    event = models.OneToOneField(Event, verbose_name='awesome event')
+
+
+class Guest(models.Model):
+    event = models.OneToOneField(Event)
+    name = models.CharField(max_length=255)
+
+    class Meta:
+        verbose_name = "awesome guest"
+
+
+class EventGuide(models.Model):
+    event = models.ForeignKey(Event, on_delete=models.DO_NOTHING)

example/blog/tests/__init__.py

@@ -4,3 +4,4 @@ from test_builtin_api_resources import *
 from test_permissions import *
 from test_modelforms import *
 from test_views import *
+from test_nestedobjects import *

example/blog/tests/test_nestedobjects.py

@@ -0,0 +1,70 @@
+from django.db import DEFAULT_DB_ALIAS
+from django.test import TestCase
+
+from djadmin2.utils import NestedObjects
+
+from ..models import Count, Event, EventGuide, Guest, Location
+
+
+# Largely taken from the Django core.
+# https://github.com/django/django/blob/1.5.1/tests/regressiontests/admin_util/tests.py
+class NestedObjectsTests(TestCase):
+    """
+    Tests for ``NestedObject`` utility collection.
+    """
+    def setUp(self):
+        self.n = NestedObjects(using=DEFAULT_DB_ALIAS)
+        self.objs = [Count.objects.create(num=i) for i in range(5)]
+
+    def _check(self, target):
+        self.assertEqual(self.n.nested(lambda obj: obj.num), target)
+
+    def _connect(self, i, j):
+        self.objs[i].parent = self.objs[j]
+        self.objs[i].save()
+
+    def _collect(self, *indices):
+        self.n.collect([self.objs[i] for i in indices])
+
+    def test_unrelated_roots(self):
+        self._connect(2, 1)
+        self._collect(0)
+        self._collect(1)
+        self._check([0, 1, [2]])
+
+    def test_siblings(self):
+        self._connect(1, 0)
+        self._connect(2, 0)
+        self._collect(0)
+        self._check([0, [1, 2]])
+
+    def test_non_added_parent(self):
+        self._connect(0, 1)
+        self._collect(0)
+        self._check([0])
+
+    def test_cyclic(self):
+        self._connect(0, 2)
+        self._connect(1, 0)
+        self._connect(2, 1)
+        self._collect(0)
+        self._check([0, [1, [2]]])
+
+    def test_queries(self):
+        self._connect(1, 0)
+        self._connect(2, 0)
+        # 1 query to fetch all children of 0 (1 and 2)
+        # 1 query to fetch all children of 1 and 2 (none)
+        # Should not require additional queries to populate the nested graph.
+        self.assertNumQueries(2, self._collect, 0)
+
+    def test_on_delete_do_nothing(self):
+        """
+        Check that the nested collector doesn't query for DO_NOTHING objects.
+        """
+        objs = [Event.objects.create()]
+        n = NestedObjects(using=None)
+        EventGuide.objects.create(event=objs[0])
+        with self.assertNumQueries(2):
+            # One for Location, one for Guest, and no query for EventGuide
+            n.collect(objs)

example/blog/tests/test_views.py

@@ -38,7 +38,7 @@ class PostListTest(BaseIntegrationTest):
         post = Post.objects.create(title="a_post_title", body="body")
         params = {'action': 'delete_selected', 'selected_model_pk': str(post.pk)}
         response = self.client.post(reverse("admin2:blog_post_index"), params)
-        self.assertInHTML('<p>Are you sure you want to delete the selected post?</p>', response.content)
+        self.assertInHTML('<p>Are you sure you want to delete the selected post? All of the following items will be deleted:</p>', response.content)
 
     def test_delete_selected_post_confirmation(self):
         post = Post.objects.create(title="a_post_title", body="body")