When deleting an account, list all objects that prevent user from deleting its account

basetheme_bootstrap/templates/registration/account_deletion.html

+{% extends 'basetheme_bootstrap/small_form_host.html' %}
+{% load basetheme_bootstrap %}
+{% load i18n %}
+
+{% block content %}
+{% if protected|length == 0 %}
+<div class="col-12 mb-2">
+    {%trans "You are about to delete your account, all data linked to your account will be removed." %}
+</div>
+{% else %}
+    <div class="col-12 mb-2">
+        {%blocktrans%}You want to delete your account, however not all data linked to your account can be removed.<br/>Hereafter
+        are listed the objects preventing you account to be deleted. Please either manually delete them, or edit them so they
+        do not remain linked to your account.{%endblocktrans%}
+    </div>
+    <div class="col-12">
+        <ul>
+            {% for p in protected %}
+            <li>
+                {%if p.get_absolute_url %}
+                <a href="{{p.get_absolute_url}}" target="_blank">{{p}}</a>
+                {%else%}
+                <b>{{p}}</b><br/>
+                Class name:{{p|get_class}}<br/>
+                Primary key:{{p.pk}}
+                {%endif%}
+            </li>
+            {% endfor %}
+        </ul>
+    </div>
+{% endif%}
+{{block.super}}
+{% endblock content%}
+
+
+{% block form %}{% if protected|length == 0 %}{{block.super}}{%endif%}{% endblock form %}
+
+

basetheme_bootstrap/templatetags/basetheme_bootstrap.py

@@ -112,3 +112,8 @@ def basetheme_bootstrap_template_if_not_redefined(template_name):
         return localized_template_name
     except template.TemplateDoesNotExist:
         return "basetheme_bootstrap/" + template_name
+
+
+@register.filter(name='get_class')
+def get_class(value):
+  return value.__class__.__name__
\ No newline at end of file

basetheme_bootstrap/views.py

 import logging
 
+from django.db import router
 from django import forms
 from django.conf import settings
 from django.contrib import messages
+from django.contrib.admin.utils import NestedObjects
 from django.contrib.auth import update_session_auth_hash, authenticate, login, get_user_model
 from django.contrib.auth.decorators import login_required
 from django.contrib.auth.forms import PasswordChangeForm
@@ -187,13 +189,18 @@ def user_delete(request):
                 messages.error(request, e)
     else:
         form = UserDeleteForm(instance=request.user)
-    return render(request, 'registration/small_form_host.html', {
+    # Inspired from auth/admin.py#get_deleted_objects
+    collector = NestedObjects(using=router.db_for_write(get_user_model()))
+    collector.collect([request.user,])
+    return render(request, 'registration/account_deletion.html', {
         'title': ugettext('Account deletion'),
         'submit_text': ugettext('Delete account and all related data'),
         'form': form,
+        'protected': collector.protected,
         'medium_width': True,
         'btn_classes': 'btn-lg btn-danger text-center',
         'btn_container_classes': 'text-center',
+        'custom_css_width':' ',
     })
 
 

setup.py

@@ -7,7 +7,7 @@ readme = open('README.rst').read()
 
 setup(
     name='django-basetheme-bootstrap',
-    version='0.2.37',
+    version='0.2.38',
     description='Django Basetheme Bootstrap',
     long_description=readme,
     author='Bryan Brancotte',

test_app_1/migrations/0003_protectedmodel.py

+# Generated by Django 3.0.4 on 2020-06-23 11:58
+
+from django.conf import settings
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('test_app_1', '0002_auto_20191015_1154'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='ProtectedModel',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('owner', models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, to=settings.AUTH_USER_MODEL)),
+            ],
+        ),
+    ]

test_app_1/models.py

 from django.conf import settings
+from django.contrib.auth import get_user_model
 from django.db import models
 from django.utils.translation import gettext_lazy as _
 
 from basetheme_bootstrap import user_preferences
 
 
+class ProtectedModel(models.Model):
+    owner = models.ForeignKey(
+        get_user_model(),
+        on_delete=models.PROTECT,
+    )
+
+    # def get_absolute_url(self):
+    #     return "rr"
+
 class MyUserPreferences(user_preferences.UserPreferencesAbstractModel, models.Model):
     preferences_groups = {
         "First group": {"hide_help", "hide_help_3", "hide_help_4", "a_time_field"},