Make app AutoField configurable on first deployment

Author: browniebroke

django_celery_results/apps.py

@@ -5,11 +5,13 @@
 
 __all__ = ['CeleryResultConfig']
 
+from django_celery_results.conf import app_settings
+
 
 class CeleryResultConfig(AppConfig):
     """Default configuration for the django_celery_results app."""
 
     name = 'django_celery_results'
     label = 'django_celery_results'
     verbose_name = _('Celery Results')
-    default_auto_field = 'django.db.models.AutoField'
+    default_auto_field = app_settings.DJANGO_CELERY_RESULTS_DEFAULT_AUTO_FIELD

django_celery_results/conf.py

@@ -0,0 +1,43 @@
+"""Application settings."""
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Any
+
+from django.conf import settings as django_settings
+
+# All attributes accessed with this prefix are possible
+# to overwrite through django.conf.settings.
+SETTINGS_PREFIX = "DJANGO_CELERY_RESULTS_"
+
+
+@dataclass(frozen=True)
+class AppSettings:
+    """Proxy class to encapsulate all the app settings.
+
+    This instance should be accessed via the singleton
+    ``django_celery_results.conf.app_settings``.
+
+    You shouldn't have to set any of these yourself, the class checks a Django
+    settings with the same name and use these if defined, defaulting to the
+    values documented here.
+    """
+
+    DJANGO_CELERY_RESULTS_DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'
+
+    def __getattribute__(self, __name: str) -> Any:
+        """Check if a Django project settings should override the app default.
+
+        In order to avoid returning any random properties of the Django
+        settings, we first inspect the prefix.
+        """
+        if (
+            __name.startswith(SETTINGS_PREFIX)
+            and hasattr(django_settings, __name)
+        ):
+            return getattr(django_settings, __name)
+
+        return super().__getattribute__(__name)
+
+
+app_settings = AppSettings()

django_celery_results/migrations/0001_initial.py

@@ -1,5 +1,11 @@
 from django.conf import settings
 from django.db import migrations, models
+from django.utils.module_loading import import_string
+
+from django_celery_results.conf import app_settings
+
+auto_field_class = import_string(
+    app_settings.DJANGO_CELERY_RESULTS_DEFAULT_AUTO_FIELD)
 
 
 class Migration(migrations.Migration):
@@ -13,7 +19,7 @@ class Migration(migrations.Migration):
         migrations.CreateModel(
             name='TaskResult',
             fields=[
-                ('id', models.AutoField(auto_created=True,
+                ('id', auto_field_class(auto_created=True,
                                         primary_key=True,
                                         serialize=False,
                                         verbose_name='ID')),

django_celery_results/migrations/0008_chordcounter.py

@@ -2,6 +2,12 @@
 
 from django.conf import settings
 from django.db import migrations, models
+from django.utils.module_loading import import_string
+
+from django_celery_results.conf import app_settings
+
+auto_field_class = import_string(
+    app_settings.DJANGO_CELERY_RESULTS_DEFAULT_AUTO_FIELD)
 
 
 class Migration(migrations.Migration):
@@ -14,7 +20,7 @@ class Migration(migrations.Migration):
         migrations.CreateModel(
             name='ChordCounter',
             fields=[
-                ('id', models.AutoField(
+                ('id', auto_field_class(
                     auto_created=True,
                     primary_key=True,
                     serialize=False,

django_celery_results/migrations/0009_groupresult.py

@@ -1,6 +1,12 @@
 # Generated by Django 3.2 on 2021-04-19 14:55
 from django.conf import settings
 from django.db import migrations, models
+from django.utils.module_loading import import_string
+
+from django_celery_results.conf import app_settings
+
+auto_field_class = import_string(
+    app_settings.DJANGO_CELERY_RESULTS_DEFAULT_AUTO_FIELD)
 
 
 class FakeAddIndex(migrations.AddIndex):
@@ -28,7 +34,7 @@ class Migration(migrations.Migration):
         migrations.CreateModel(
             name='GroupResult',
             fields=[
-                ('id', models.AutoField(
+                ('id', auto_field_class(
                     auto_created=True,
                     primary_key=True,
                     serialize=False,

docs/configuration.rst

@@ -0,0 +1,19 @@
+Configuration
+=============
+
+These are the available settings that can be configured in your Django
+project's settings module by defining a setting with the same name.
+
+* ``DJANGO_CELERY_RESULTS_DEFAULT_AUTO_FIELD``: The ``default_auto_field`` used
+  when first deploying the app, defaults to ``django.db.models.BigAutoField``
+  if unspecified.
+
+  This is only used for the first deployment and
+  and has no effect if changed after this point. If you want to change its
+  value after the initial deployment, you should migrate back to zero and
+  re-apply migrations again::
+
+    $ python manage.py migrate django_celery_results zero
+    $ python manage.py migrate django_celery_results
+
+  This will drop and recreate all tables used by django-celery-results.

docs/index.rst

@@ -12,6 +12,7 @@ Contents
 
     getting_started
     injecting_metadata
+    configuration
     copyright
 
 .. toctree::

setup.cfg

@@ -9,7 +9,7 @@ markers =
 [flake8]
 # classes can be lowercase, arguments and variables can be uppercase
 # whenever it makes the code more readable.
-ignore = N806, N802, N801, N803
+ignore = N806, N802, N801, N803, W503
 
 [pep257]
 convention=google