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):
         """