Bugfix for auto-backup task (#4406)

* Bugfix for auto-backup task

- Dont' mix datetime with timezone

* Use different variable names

- If old names are stuck in the database, error could still occur

* Exclude internal settings from API

* Make INVENTREE_LATEST_VERSION setting an internal one

InvenTree/common/api.py

@@ -187,7 +187,7 @@ class SettingsList(ListAPI):
 class GlobalSettingsList(SettingsList):
     """API endpoint for accessing a list of global settings objects."""
 
-    queryset = common.models.InvenTreeSetting.objects.all()
+    queryset = common.models.InvenTreeSetting.objects.exclude(key__startswith="_")
     serializer_class = common.serializers.GlobalSettingsSerializer
 
 
@@ -216,7 +216,7 @@ class GlobalSettingsDetail(RetrieveUpdateAPI):
     """
 
     lookup_field = 'key'
-    queryset = common.models.InvenTreeSetting.objects.all()
+    queryset = common.models.InvenTreeSetting.objects.exclude(key__startswith="_")
     serializer_class = common.serializers.GlobalSettingsSerializer
 
     def get_object(self):

InvenTree/common/models.py

@@ -180,6 +180,10 @@ class BaseInvenTreeSetting(models.Model):
         """
         results = cls.objects.all()
 
+        if exclude_hidden:
+            # Keys which start with an undersore are used for internal functionality
+            results = results.exclude(key__startswith='_')
+
         # Optionally filter by user
         if user is not None:
             results = results.filter(user=user)