From 1f1ed79ee5c97d6c7d62298ae12c26494be511e7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Luk=C3=A1=C5=A1=20Kucharczyk?= <lukas@kucharczyk.xyz>
Date: Wed, 10 Jan 2024 16:57:01 +0100
Subject: [PATCH] Optimize session listing

---
 CHANGELOG.md                       |  4 +++-
 games/templates/list_sessions.html |  4 ++--
 games/views.py                     | 28 ++++++++++++++++------------
 3 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 86605b2..29a2e9a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,7 +3,9 @@
 ## Improved
 * game overview: improve how editions and purchases are displayed
 * add purchase: only allow choosing purchases of selected edition
-* session list: starting and ending sessions is much faster/doest not reload the page
+* session list:
+  * starting and ending sessions is much faster/doest not reload the page
+  * listing sessions is much faster
 
 ## 1.5.1 / 2023-11-14 21:10+01:00
 
diff --git a/games/templates/list_sessions.html b/games/templates/list_sessions.html
index 8d3449e..26b1670 100644
--- a/games/templates/list_sessions.html
+++ b/games/templates/list_sessions.html
@@ -4,7 +4,7 @@
     {{ title }}
 {% endblock title %}
 {% block content %}
-    {% if dataset.count >= 1 %}
+    {% if dataset_count >= 1 %}
         <div class="mx-auto text-center my-4">
             <a id="last-session-start"
                 href="{% url 'start_session_same_as_last' last.id %}"
@@ -17,7 +17,7 @@
             </a>
         </div>
     {% endif %}
-    {% if dataset.count != 0 %}
+    {% if dataset_count != 0 %}
         <table class="responsive-table">
             <thead>
                 <tr>
diff --git a/games/views.py b/games/views.py
index 25e30ee..be2b8a9 100644
--- a/games/views.py
+++ b/games/views.py
@@ -277,35 +277,39 @@ def list_sessions(
     context = {}
     context["title"] = "Sessions"
 
+    dataset = Session.objects.prefetch_related(
+        "purchase", "purchase__edition", "purchase__edition__game"
+    ).order_by("-timestamp_start")
+
     if filter == "purchase":
-        dataset = Session.objects.filter(purchase=purchase_id)
+        dataset = dataset.filter(purchase=purchase_id)
         context["purchase"] = Purchase.objects.get(id=purchase_id)
     elif filter == "platform":
-        dataset = Session.objects.filter(purchase__platform=platform_id)
+        dataset = dataset.filter(purchase__platform=platform_id)
         context["platform"] = Platform.objects.get(id=platform_id)
     elif filter == "edition":
-        dataset = Session.objects.filter(purchase__edition=edition_id)
+        dataset = dataset.filter(purchase__edition=edition_id)
         context["edition"] = Edition.objects.get(id=edition_id)
     elif filter == "game":
-        dataset = Session.objects.filter(purchase__edition__game=game_id)
+        dataset = dataset.filter(purchase__edition__game=game_id)
         context["game"] = Game.objects.get(id=game_id)
     elif filter == "ownership_type":
-        dataset = Session.objects.filter(purchase__ownership_type=ownership_type)
+        dataset = dataset.filter(purchase__ownership_type=ownership_type)
         context["ownership_type"] = dict(Purchase.OWNERSHIP_TYPES)[ownership_type]
     elif filter == "recent":
         current_year = timezone.now().year
         first_day_of_year = timezone.make_aware(datetime(current_year, 1, 1))
-        dataset = Session.objects.filter(
-            timestamp_start__gte=first_day_of_year
-        ).order_by("-timestamp_start")
+        dataset = dataset.filter(timestamp_start__gte=first_day_of_year).order_by(
+            "-timestamp_start"
+        )
         context["title"] = "This year"
-    else:
-        # by default, sort from newest to oldest
-        dataset = Session.objects.order_by("-timestamp_start")
 
     context["dataset"] = dataset
+    context["dataset_count"] = dataset.count()
     try:
-        context["last"] = Session.objects.latest()
+        context["last"] = Session.objects.prefetch_related(
+            "purchase__platform"
+        ).latest()
     except ObjectDoesNotExist:
         context["last"] = None