[damned-lies] Avoid null values in global statistics query

[Claude Paroz <claudep src gnome org>]

commit 1cfe71200178b00eff9ca39ed3d89010ed35eca2
Author: Claude Paroz <claude 2xlibre net>
Date:   Fri Mar 19 08:28:19 2021 +0100

    Avoid null values in global statistics query

 stats/models.py | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)
---
diff --git a/stats/models.py b/stats/models.py
index fb27f1f4..bdcde8c1 100644
--- a/stats/models.py
+++ b/stats/models.py
@@ -21,6 +21,7 @@ from django.utils.functional import cached_property
 from django.utils.translation import ngettext, gettext as _, gettext_noop
 from django.utils import dateformat
 from django.db import models
+from django.db.models.functions import Coalesce
 
 from common.fields import DictionaryField, JSONField
 from common.utils import is_site_admin, run_shell_command
@@ -1097,9 +1098,12 @@ class Release(models.Model):
         query = Statistics.objects.filter(language__isnull=False, branch__releases=self
             ).exclude(domain__in=self.excluded_domains
             ).values('domain__dtype', 'language'
-            ).annotate(trans=models.Sum('full_po__translated'), fuzzy=models.Sum('full_po__fuzzy'),
-                       trans_p=models.Sum('part_po__translated'), fuzzy_p=models.Sum('part_po__fuzzy'),
-                       locale=models.Min('language__locale'), lang_name=models.Min('language__name')
+            ).annotate(
+                trans=Coalesce(models.Sum('full_po__translated'), models.Value(0)),
+                fuzzy=Coalesce(models.Sum('full_po__fuzzy'), models.Value(0)),
+                trans_p=Coalesce(models.Sum('part_po__translated'), models.Value(0)),
+                fuzzy_p=Coalesce(models.Sum('part_po__fuzzy'), models.Value(0)),
+                locale=models.Min('language__locale'), lang_name=models.Min('language__name')
             ).order_by('domain__dtype', 'trans')
         stats = {}
         total_docstrings, total_uistrings = self.total_strings()