vastly reduce page view queries, cache common data

shiftregister/app/models.py

@@ -46,7 +46,7 @@ class Shift(models.Model):
                     )
                 ),
             )
-        )
+        ).select_related("room")
 
     def __str__(self):
         return f"{self.room.name}: {self.start_at}"

shiftregister/app/views.py

@@ -2,6 +2,7 @@ from django.shortcuts import render, redirect, get_object_or_404
 from .models import Shift, LoginToken, Helper, ShiftRegistration
 from django.db import transaction
 from django.db.models import F, Count, Q, ExpressionWrapper
+from django.core.cache import cache
 from .forms import RegisterForm, EmptyForm, AstaForm
 from django.db.models.fields import DateTimeField
 from datetime import timedelta
@@ -21,8 +22,13 @@ def index(request):
     if request.session.get("last_seen_shift"):
         del request.session["last_seen_shift"]
 
+    days = cache.get("event_days")
+    if not days:
+        days = Shift.objects.filter(deleted=False).datetimes("start_at", "day").all()
+        cache.set("event_days", days)
+
     context = {
-        "days": Shift.objects.filter(deleted=False).datetimes("start_at", "day"),
+        "days": days,
         "enable_asta": global_preferences["helper__enable_asta"],
     }
 
@@ -58,7 +64,7 @@ def index(request):
             deleted=False,
         )
         .order_by("start_at")
-        for day in Shift.objects.datetimes("start_at", "day")
+        for day in days
     )
     if request.helper:
         free_shifts = (
@@ -175,7 +181,7 @@ def register(request):
 
 @event_state
 def shift(request, shiftid):
-    shift = get_object_or_404(Shift, pk=shiftid)
+    shift = get_object_or_404(Shift.with_reg_count(), pk=shiftid)
     helper = request.helper
     context = {
         "enable_asta": global_preferences["helper__enable_asta"],