fix: deletion of version objects blocked by source fields (#320)

* fix: deletion of version objects blocked by source fields

* Add: Option to turn deletion on or off, test for migrations

* Fix flake8 issues with migration test

* Update docs

* Add tests for setting

* Fix isort

* Fix codeql warning

* Update test_settings.py

* Update docs/settings.rst

Co-authored-by: Andrew Aikman <[email protected]>

* Update docs/settings.rst

Co-authored-by: Andrew Aikman <[email protected]>

* Fix:		move setting to conf.py

* Update test

* isort tests

---------

Co-authored-by: Andrew Aikman <[email protected]>

Author: fsbraun

djangocms_versioning/apps.py

@@ -6,6 +6,7 @@
 class VersioningConfig(AppConfig):
     name = "djangocms_versioning"
     verbose_name = _("django CMS Versioning")
+    default_auto_field = 'django.db.models.AutoField'
 
     def ready(self):
         from cms.models import contentmodels, fields

djangocms_versioning/conf.py

@@ -12,3 +12,7 @@
 DEFAULT_USER = getattr(
     settings, "DJANGOCMS_VERSIONING_DEFAULT_USER", None
 )
+
+ALLOW_DELETING_VERSIONS = getattr(
+    settings, "DJANGOCMS_VERSIONING_ALLOW_DELETING_VERSIONS", False
+)

djangocms_versioning/migrations/0003_version.py

@@ -29,7 +29,7 @@ class Migration(migrations.Migration):
                     ),
                 ),
                 ("label", models.TextField()),
-                ("created", models.DateTimeField(auto_now_add=True)),
+                ("created", models.DateTimeField(auto_now_add=True, verbose_name="Created")),
                 ("object_id", models.PositiveIntegerField()),
                 (
                     "content_type",

djangocms_versioning/migrations/0014_version_source.py

@@ -3,7 +3,8 @@
 from __future__ import unicode_literals
 
 from django.db import migrations, models
-import django.db.models.deletion
+
+import djangocms_versioning.models
 
 
 class Migration(migrations.Migration):
@@ -17,7 +18,7 @@ class Migration(migrations.Migration):
             field=models.ForeignKey(
                 blank=True,
                 null=True,
-                on_delete=django.db.models.deletion.PROTECT,
+                on_delete=djangocms_versioning.models.allow_deleting_versions,
                 to="djangocms_versioning.Version",
                 verbose_name="source",
             ),

djangocms_versioning/migrations/0015_version_modified.py

@@ -14,6 +14,6 @@ class Migration(migrations.Migration):
         migrations.AddField(
             model_name="version",
             name="modified",
-            field=models.DateTimeField(default=django.utils.timezone.now),
+            field=models.DateTimeField(default=django.utils.timezone.now, verbose_name="Modified"),
         )
     ]

djangocms_versioning/models.py

@@ -10,6 +10,8 @@
 
 from django_fsm import FSMField, can_proceed, transition
 
+from djangocms_versioning.conf import ALLOW_DELETING_VERSIONS
+
 from . import constants, versionables
 from .conditions import Conditions, in_state
 from .operations import send_post_version_operation, send_pre_version_operation
@@ -21,6 +23,13 @@
     emit_content_change = None
 
 
+def allow_deleting_versions(collector, field, sub_objs, using):
+    if ALLOW_DELETING_VERSIONS:
+        models.SET_NULL(collector, field, sub_objs, using)
+    else:
+        models.PROTECT(collector, field, sub_objs, using)
+
+
 class VersionQuerySet(models.QuerySet):
     def get_for_content(self, content_object):
         """Returns Version object corresponding to provided content object
@@ -85,7 +94,7 @@ class Version(models.Model):
         "self",
         null=True,
         blank=True,
-        on_delete=models.PROTECT,
+        on_delete=allow_deleting_versions,
         verbose_name=_("source"),
     )
     objects = VersionQuerySet.as_manager()

docs/index.rst

@@ -15,6 +15,7 @@ Welcome to "djangocms-versioning"'s documentation!
    api/signals
    api/customizing_version_list
    api/management_commands
+   settings
 
 .. toctree::
    :maxdepth: 2

docs/settings.rst

@@ -0,0 +1,23 @@
+Settings for djangocms Versioning
+=================================
+
+
+.. py:attribute:: DJANGOCMS_VERSIONING_ALLOW_DELETING_VERSIONS
+
+    Defaults to ``False``
+
+    This setting controls if the ``source`` field of a ``Version`` object is
+    protected. It is protected by default which implies that Django will not allow a user
+    to delete a version object which itself is a source for another version object.
+    This implies that the corresponding content and grouper objects cannot be
+    deleted either.
+
+    This is to protect the record of how different versions have come about.
+
+    If set to ``True`` users can delete version objects if the have the appropriate
+    rights. Set this to ``True`` if you want users to be able to delete versioned
+    objects and you do not need a full history of versions, e.g. for documentation
+    purposes.
+
+    The latest version (which is not a source of a newer version) can always be
+    deleted (if the user has the appropriate rights).

docs/upgrade/2.0.0.rst

@@ -35,6 +35,15 @@ Status indicators in page tree
   make sure that at least version 3.2.1 is installed. Older versions contain
   a bug that interferes with djangocms-versioning's icons.
 
+Deletion protection
+-------------------
+
+By default ``Version`` objects which are sources for later versions are
+protected from deletion. This implies that neither the corresponding content
+object nor the grouper object can be deleted. To allow deletion of ``Version``
+objects set ``DJANGOCMS_VERSIONING_ALLOW_DELETING_VERSIONS`` to ``True`` in
+the project's ``settings.py``.
+
 
 Backwards incompatible changes in 2.0.0
 =======================================

tests/test_0_migrations.py

@@ -0,0 +1,31 @@
+# original from
+# http://tech.octopus.energy/news/2016/01/21/testing-for-missing-migrations-in-django.html
+
+# Needs to run as first test to avoid generating migrations for proxy version models.
+
+from io import StringIO
+
+from django.core.management import call_command
+from django.test import TestCase
+
+
+class MigrationTestCase(TestCase):
+    def test_for_missing_migrations(self):
+        output = StringIO()
+        options = {
+            "interactive": False,
+            "dry_run": True,
+            "stdout": output,
+            "check_changes": True,
+        }
+
+        try:
+            call_command("makemigrations", "djangocms_versioning", **options)
+        except SystemExit as e:
+            status_code = str(e)
+        else:
+            # the "no changes" exit code is 0
+            status_code = "0"
+
+        if status_code == "1":
+            self.fail(f"There are missing migrations:\n {output.getvalue()}")