From ea1be44469d40c0015860f7682726c367bc67dac Mon Sep 17 00:00:00 2001
From: David van Buiten <david.vanbuiten@gmail.com>
Date: Mon, 18 Sep 2023 14:48:22 +0200
Subject: [PATCH] This commit adds a new abstract class, CustomPermission,
 essential for creating custom permissions independent of existing models, as
 Django auth Permissions necessitate a ContentType association. Additionally,
 a sync_custom_permission function is included, which responds to the
 DjangoSignal post_migrate, facilitating the creation of custom permissions if
 they do not already exist.

---
 app/signals/apps/signals/apps.py              |  1 +
 app/signals/apps/signals/models/permission.py | 48 +++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 app/signals/apps/signals/models/permission.py

diff --git a/app/signals/apps/signals/apps.py b/app/signals/apps/signals/apps.py
index 707c16647..59fc3799e 100644
--- a/app/signals/apps/signals/apps.py
+++ b/app/signals/apps/signals/apps.py
@@ -10,3 +10,4 @@ class SignalsConfig(AppConfig):
     def ready(self):
         # Import Django signals to connect receiver functions.
         import signals.apps.signals.signal_receivers  # noqa
+        import signals.apps.signals.models.permission  # noqa
diff --git a/app/signals/apps/signals/models/permission.py b/app/signals/apps/signals/models/permission.py
new file mode 100644
index 000000000..077601334
--- /dev/null
+++ b/app/signals/apps/signals/models/permission.py
@@ -0,0 +1,48 @@
+# SPDX-License-Identifier: MPL-2.0
+# Copyright (C) 2023 Gemeente Amsterdam
+import logging
+
+from django.contrib.auth.models import Permission
+from django.contrib.contenttypes.models import ContentType
+from django.db import models
+from django.db.models.signals import post_migrate
+from django.dispatch import receiver
+
+logger = logging.getLogger(__name__)
+
+
+class CustomPermission(models.Model):
+    """
+    An abstract class for creating custom permissions that do not belong to any existing model.
+
+    Django's built-in auth Permissions require a ContentType association.
+    """
+    class Meta:
+        abstract = True
+
+
+@receiver(post_migrate)
+def sync_custom_permissions(sender, **kwargs):
+    """
+    Synchronize custom permissions after a migration.
+
+    This function listens to the post_migrate signal in Django and creates custom permissions
+    if they do not already exist.
+
+    These custom permissions are associated with the CustomPermission model.
+
+    Args:
+        sender: The sender of the signal (usually the app with the migrations).
+        **kwargs: Additional keyword arguments provided by the signal.
+    """
+    content_type = ContentType.objects.get_for_model(CustomPermission, for_concrete_model=False)
+
+    custom_permissions = [
+        # Custom permission to allow users to create i18next translation files.
+        ('add_i18next_translation_file', 'Can create i18next translation file')
+    ]
+
+    for codename, name in custom_permissions:
+        if not Permission.objects.filter(name=name, codename=codename, content_type=content_type).exists():
+            logger.info(f'Creating custom permission "{codename}" with name "{name}"')
+            Permission.objects.create(name=name, codename=codename, content_type=content_type)