From a0101b9a7566b5296c3490ce3592984976553807 Mon Sep 17 00:00:00 2001
From: Alban Gruin
Date: Sat, 20 Jan 2018 22:28:21 +0100
Subject: On cache les groupes qui n’ont plus de cours La requête est assez
 longue à s’effectuer sur SQLite, mais pas sur PostgreSQL

---
 models.py | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

(limited to 'models.py')

diff --git a/models.py b/models.py
index 15f378a..c122bfd 100644
--- a/models.py
+++ b/models.py
@@ -16,7 +16,7 @@
 from functools import reduce
 
 from django.db import models
-from django.db.models import Manager, Q
+from django.db.models import Count, Manager, OuterRef, Q, Subquery
 from django.db.models.functions import ExtractWeek, ExtractYear
 from django.utils import timezone
 from django.utils.text import slugify
@@ -104,6 +104,13 @@ class GroupManager(Manager):
                                           mention=group.mention,
                                           source=group.source)
 
+    def get_relevant_groups(self, start, **criteria):
+        courses = Course.objects.filter(groups=OuterRef("pk"), begin__gte=start) \
+                                .only("pk")[:1]
+        return self.get_queryset().annotate(c=Subquery(courses,
+                                                       output_field=models.IntegerField())) \
+                                  .filter(c__isnull=False, **criteria).order_by("name")
+
 
 class Group(SlugModel):
     objects = GroupManager()
-- 
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