From 94fabdf7c300d3d164d25e7db1b60c77612c943c Mon Sep 17 00:00:00 2001
From: Camilo Nova <camilo.nova@axiacore.com>
Date: Wed, 14 Sep 2016 12:22:32 -0500
Subject: [PATCH] Added signal on change, refs #158

---
 constance/__init__.py                   | 4 ++++
 constance/apps.py                       | 4 +---
 constance/backends/database/__init__.py | 7 +++++--
 constance/backends/redisd.py            | 2 ++
 4 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/constance/__init__.py b/constance/__init__.py
index 21c429c..5ed4087 100644
--- a/constance/__init__.py
+++ b/constance/__init__.py
@@ -1,3 +1,4 @@
+import django.dispatch
 from django.utils.functional import LazyObject
 
 __version__ = '1.2.1'
@@ -10,4 +11,7 @@ class LazyConfig(LazyObject):
         from .base import Config
         self._wrapped = Config()
 
+
 config = LazyConfig()
+
+updated_signal = django.dispatch.Signal(providing_args=['key', 'value'])
diff --git a/constance/apps.py b/constance/apps.py
index bd8a894..8aebcc5 100644
--- a/constance/apps.py
+++ b/constance/apps.py
@@ -1,5 +1,4 @@
 from django.db.models import signals
-from django import VERSION
 from django.apps import AppConfig
 from django.utils.translation import ugettext_lazy as _
 
@@ -22,11 +21,10 @@ class ConstanceConfig(AppConfig):
         from django.contrib.contenttypes.models import ContentType
 
         if ContentType._meta.installed and Permission._meta.installed:
-            extra = {} if VERSION >= (1, 8) else {'name': 'config'}
             content_type, created = ContentType.objects.get_or_create(
                 app_label='constance',
                 model='config',
-                **extra)
+            )
 
             permission, created = Permission.objects.get_or_create(
                 name='Can change config',
diff --git a/constance/backends/database/__init__.py b/constance/backends/database/__init__.py
index 01cf260..6cb5a96 100644
--- a/constance/backends/database/__init__.py
+++ b/constance/backends/database/__init__.py
@@ -5,6 +5,7 @@ from django.db.models.signals import post_save
 
 from .. import Backend
 from ... import settings
+from ... import updated_signal
 
 
 class DatabaseBackend(Backend):
@@ -25,8 +26,8 @@ class DatabaseBackend(Backend):
             if isinstance(self._cache, LocMemCache):
                 raise ImproperlyConfigured(
                     "The CONSTANCE_DATABASE_CACHE_BACKEND setting refers to a "
-                    "subclass of Django's local-memory backend (%r). Please set "
-                    "it to a backend that supports cross-process caching."
+                    "subclass of Django's local-memory backend (%r). Please "
+                    "set it to a backend that supports cross-process caching."
                     % settings.DATABASE_CACHE_BACKEND)
         else:
             self._cache = None
@@ -86,6 +87,8 @@ class DatabaseBackend(Backend):
         if self._cache:
             self._cache.set(key, value)
 
+        updated_signal.send(sender='constance', key=key, value=value)
+
     def clear(self, sender, instance, created, **kwargs):
         if self._cache and not created:
             keys = [self.add_prefix(k)
diff --git a/constance/backends/redisd.py b/constance/backends/redisd.py
index abf24f4..3b24398 100644
--- a/constance/backends/redisd.py
+++ b/constance/backends/redisd.py
@@ -4,6 +4,7 @@ from django.utils.six.moves import zip
 
 from . import Backend
 from .. import settings, utils
+from .. import updated_signal
 
 try:
     from cPickle import loads, dumps
@@ -49,3 +50,4 @@ class RedisBackend(Backend):
 
     def set(self, key, value):
         self._rd.set(self.add_prefix(key), dumps(value))
+        updated_signal.send(sender='constance', key=key, value=value)