From 8f82d0f0807866348a1da5c43c59b7ca80cc77b2 Mon Sep 17 00:00:00 2001
From: Filipe Pina <fopina@gmail.com>
Date: Sat, 21 Jan 2023 17:12:55 +0000
Subject: [PATCH] EventRef to the rescue of typos and manual data migrations!

---
 notifications/apps.py                         | 10 +++++++
 notifications/models.py                       | 27 +++++++++++++++++++
 testapp/requirements.txt                      |  2 +-
 .../management/commands/brute_notify.py       |  8 +++---
 testapp/testapp/models.py                     |  3 +++
 5 files changed, 44 insertions(+), 6 deletions(-)
 create mode 100644 testapp/testapp/models.py

diff --git a/notifications/apps.py b/notifications/apps.py
index a8ee669..fee6648 100644
--- a/notifications/apps.py
+++ b/notifications/apps.py
@@ -1,5 +1,6 @@
 from django.apps import AppConfig
 from django.conf import settings
+from django.db.models.signals import post_migrate
 
 # IMPORT do not use "app_settings.py strategy" as that is not compatible with @override_settings (unittests)
 # this strategy is
@@ -19,3 +20,12 @@ def ready(self):
             _k = 'NOTIFICATIONS_%s' % k
             if not hasattr(settings, _k):
                 setattr(settings, _k, v)
+
+        post_migrate.connect(create_events, sender=self)
+
+
+def create_events(sender, **kwargs):
+    from .models import EventRef, Event
+
+    for ref in EventRef.get_references():
+        Event.objects.update_or_create(name=ref.name, defaults={'description': ref.description})
diff --git a/notifications/models.py b/notifications/models.py
index 3768693..d8c30c2 100644
--- a/notifications/models.py
+++ b/notifications/models.py
@@ -4,6 +4,33 @@
 from django.template.defaultfilters import truncatechars
 
 
+class EventRef:
+    """
+    EventRef is not a model but instead a reference to current (or future, if not yet migrated) Event.
+    This allows hardcoded events to be statically referenced and automatically provisioned
+    (instead of requiring a data-only migration or the event to be manually added before code is used)
+    """
+
+    __refs = []
+
+    def __init__(self, name, description):
+        self.__class__.__refs.append(self)
+        self.name = name
+        self.description = description
+
+    def __repr__(self) -> str:
+        # to be able to use EventRef directly in Event.name queries
+        return self.name
+
+    def get_event(self) -> 'Event':
+        Event.objects.get(name=self)
+
+    @classmethod
+    def get_references(cls):
+        # return a copy of the references
+        return cls.__refs[:]
+
+
 class Event(models.Model):
     name = models.CharField(max_length=50, primary_key=True)
     description = models.TextField(blank=True)
diff --git a/testapp/requirements.txt b/testapp/requirements.txt
index 3ebbd1b..c9680e0 100644
--- a/testapp/requirements.txt
+++ b/testapp/requirements.txt
@@ -2,4 +2,4 @@
 pytest==6.2.5
 pytest-cov==2.12.1
 pytest-django==4.4.0
-black==20.8b1
+black==22.12.0
diff --git a/testapp/testapp/management/commands/brute_notify.py b/testapp/testapp/management/commands/brute_notify.py
index ae0c8e5..dd646a2 100644
--- a/testapp/testapp/management/commands/brute_notify.py
+++ b/testapp/testapp/management/commands/brute_notify.py
@@ -2,6 +2,7 @@
 from django.core.management import call_command
 
 from notifications import utils, models, blocks
+from testapp.models import TEST_EVENT
 
 
 class Command(BaseCommand):
@@ -20,10 +21,7 @@ def add_arguments(self, parser):
         )
 
     def handle(self, *args, **options):
-        # force create event
-        e, _ = models.Event.objects.get_or_create(name='testit')
-        e.subscription_set.update_or_create(
-            event=e,
+        TEST_EVENT.get_event().subscription_set.update_or_create(
             defaults={
                 'target': options['target'],
                 'service': models.Subscription.Service.MAIL if options['mail'] else models.Subscription.Service.SLACK,
@@ -61,7 +59,7 @@ def handle(self, *args, **options):
             x = utils.notify(e.name, nblocks)
             self.stdout.write(f'{x} notifications created')
             call_command('notification_sender', run_once=True)
-        return
+
         if options['spam']:
             x = 0
             for y in range(options['spam']):
diff --git a/testapp/testapp/models.py b/testapp/testapp/models.py
new file mode 100644
index 0000000..4c525bb
--- /dev/null
+++ b/testapp/testapp/models.py
@@ -0,0 +1,3 @@
+from notifications.models import EventRef
+
+TEST_EVENT = EventRef('testit', 'event for testing purposes (with brute_notify command)')