Réduit le nombre de requêtes SQL sur la page /mp/

zds/mp/managers.py

@@ -12,7 +12,8 @@ def get_private_topics_of_user(self, user_id):
             super()
             .get_queryset()
             .filter(Q(participants__in=[user_id]) | Q(author=user_id))
-            .select_related("author")
+            .select_related("author__profile")
+            .prefetch_related("participants")
             .distinct()
             .order_by("-last_message__pubdate")
             .all()

zds/mp/models.py

@@ -67,6 +67,11 @@ class Meta:
     pubdate = models.DateTimeField("Date de création", auto_now_add=True, db_index=True)
     objects = PrivateTopicManager()
 
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._cache_is_unread = dict()
+        self._cache_first_post = None
+
     @staticmethod
     def create(title, subtitle, author, recipients):
         limit = PrivateTopic._meta.get_field("title").max_length
@@ -140,7 +145,10 @@ def first_post(self):
         :return: PrivateTopic object first answer (PrivatePost)
         :rtype: PrivatePost object or None
         """
-        return PrivatePost.objects.filter(privatetopic=self).order_by("position_in_topic").first()
+        if self._cache_first_post is None:
+            self._cache_first_post = PrivatePost.objects.filter(privatetopic=self).order_by("position_in_topic").first()
+
+        return self._cache_first_post
 
     def last_read_post(self, user=None):
         """
@@ -212,7 +220,7 @@ def resolve_last_read_post_absolute_url(self, user=None):
             return self.first_unread_post().get_absolute_url()
 
     def resolve_last_post_pk_and_pos_read_by_user(self, user):
-        """Determine the primary ey of position of the last post read by a user.
+        """Determine the primary key of position of the last post read by a user.
 
         :param user: the current (authenticated) user. Please do not try with unauthenticated user, il would lead to a \
         useless request.
@@ -252,7 +260,10 @@ def is_unread(self, user=None):
         if user is None:
             user = get_current_user()
 
-        return is_privatetopic_unread(self, user)
+        if user not in self._cache_is_unread:
+            self._cache_is_unread[user] = is_privatetopic_unread(self, user)
+
+        return self._cache_is_unread[user]
 
     def is_author(self, user):
         """

zds/mp/tests/tests_models.py

@@ -8,7 +8,14 @@
 
 from zds.member.tests.factories import ProfileFactory
 from zds.mp.tests.factories import PrivateTopicFactory, PrivatePostFactory
-from zds.mp.models import mark_read, is_privatetopic_unread, is_reachable, NotParticipatingError, NotReachableError
+from zds.mp.models import (
+    is_privatetopic_unread,
+    is_reachable,
+    mark_read,
+    NotParticipatingError,
+    NotReachableError,
+    PrivateTopic,
+)
 
 # by moment, i wrote the scenario to be simpler
 
@@ -105,14 +112,17 @@ def test_is_unread(self):
         # post1 - user1 - read
         # post2 - user2 - read
         mark_read(self.topic1, self.user1)
+        self.assertTrue(self.topic1.is_unread(self.user1))  # cache is working
+        self.topic1 = PrivateTopic.objects.get(pk=self.topic1.pk)  # get a new object to have an empty cache
         self.assertFalse(self.topic1.is_unread(self.user1))
 
         # scenario - topic1 :
         # post1 - user1 - read
         # post2 - user2 - read
         # post3 - user2 - unread
         PrivatePostFactory(privatetopic=self.topic1, author=self.user2, position_in_topic=3)
-
+        self.assertFalse(self.topic1.is_unread(self.user1))  # cache is working
+        self.topic1 = PrivateTopic.objects.get(pk=self.topic1.pk)  # get a new object to have an empty cache
         self.assertTrue(self.topic1.is_unread(self.user1))
 
     def test_topic_never_read_get_last_read(self):
@@ -270,12 +280,16 @@ def test_mark_read(self, topic_read):
         # post1 - user1 - read
         # post2 - user2 - read
         mark_read(self.topic1, self.profile1.user)
-        self.assertFalse(self.topic1.is_unread(self.profile1.user))
         self.assertEqual(topic_read.send.call_count, 1)
+        self.assertTrue(self.topic1.is_unread(self.profile1.user))  # cache is working
+        self.topic1 = PrivateTopic.objects.get(pk=self.topic1.pk)  # get a new object to have an empty cache
+        self.assertFalse(self.topic1.is_unread(self.profile1.user))
 
         # scenario - topic1 :
         # post1 - user1 - read
         # post2 - user2 - read
         # post3 - user2 - unread
         PrivatePostFactory(privatetopic=self.topic1, author=self.profile2.user, position_in_topic=3)
+        self.assertFalse(self.topic1.is_unread(self.profile1.user))  # cache is working
+        self.topic1 = PrivateTopic.objects.get(pk=self.topic1.pk)  # get a new object to have an empty cache
         self.assertTrue(self.topic1.is_unread(self.profile1.user))