Fix cache invalidation (#131)

dbtemplates/test_cases.py

@@ -1,6 +1,7 @@
 import os
 import shutil
 import tempfile
+from unittest import mock
 
 from django.conf import settings as django_settings
 from django.core.cache.backends.base import BaseCache
@@ -151,3 +152,24 @@ class DbTemplatesTestCase(TestCase):
     def test_get_cache_name(self):
         self.assertEqual(get_cache_key('name with spaces'),
                          'dbtemplates::name-with-spaces::1')
+
+    def test_cache_invalidation(self):
+        # Add t1 into the cache of site2
+        self.t1.sites.add(self.site2)
+        with mock.patch('django.contrib.sites.models.SiteManager.get_current',
+                        return_value=self.site2):
+            result = loader.get_template("base.html").render()
+            self.assertEqual(result, 'base')
+
+        # Update content
+        self.t1.content = 'new content'
+        self.t1.save()
+        result = loader.get_template("base.html").render()
+        self.assertEqual(result, 'new content')
+
+        # Cache invalidation should work across sites.
+        # Site2 should see the new content.
+        with mock.patch('django.contrib.sites.models.SiteManager.get_current',
+                        return_value=self.site2):
+            result = loader.get_template("base.html").render()
+            self.assertEqual(result, 'new content')

dbtemplates/utils/cache.py

@@ -21,9 +21,10 @@ def get_cache_backend():
 cache = get_cache_backend()
 
 
-def get_cache_key(name):
+def get_cache_key(name, site=None):
-    current_site = Site.objects.get_current()
+    if site is None:
-    return f"dbtemplates::{slugify(name)}::{current_site.pk}"
+        site = Site.objects.get_current()
+    return f"dbtemplates::{slugify(name)}::{site.pk}"
 
 
 def get_cache_notfound_key(name):
@@ -57,4 +58,5 @@ def remove_cached_template(instance, **kwargs):
     Called via Django's signals to remove cached templates, if the template
     in the database was changed or deleted.
     """
-    cache.delete(get_cache_key(instance.name))
+    for site in instance.sites.all():
+        cache.delete(get_cache_key(instance.name, site=site))