From 0cd15b2b8dfca585a19e8b9da76039cbc112a475 Mon Sep 17 00:00:00 2001
From: "Szabo, Zoltan" <szabozoltan69@gmail.com>
Date: Sat, 29 Jun 2024 18:45:57 +0200
Subject: [PATCH] Fix event-pk query n+1 selects

---
 api/drf_views.py   | 15 ++++++++++++---
 api/serializers.py |  4 ++--
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/api/drf_views.py b/api/drf_views.py
index 3172d5e8c6..fe6a5929ff 100644
--- a/api/drf_views.py
+++ b/api/drf_views.py
@@ -668,9 +668,13 @@ def get_serializer_class(self):
     def retrieve(self, request, pk=None, *args, **kwargs):
         if pk:
             try:
+                FR = Prefetch(
+                    "field_reports",
+                    queryset=FieldReport.objects.prefetch_related("countries", "contacts"),
+                )
                 if self.request.user.is_authenticated:
                     if is_user_ifrc(self.request.user):
-                        instance = Event.objects.get(pk=pk)
+                        instance = Event.objects.prefetch_related(FR).get(pk=pk)
                     else:
                         user_countries = (
                             UserCountry.objects.filter(user=request.user.id)
@@ -678,12 +682,17 @@ def retrieve(self, request, pk=None, *args, **kwargs):
                             .union(Profile.objects.filter(user=request.user.id).values("country"))
                         )
                         instance = (
-                            Event.objects.exclude(visibility=VisibilityChoices.IFRC)
+                            Event.objects.prefetch_related(FR)
+                            .exclude(visibility=VisibilityChoices.IFRC)
                             .exclude(Q(visibility=VisibilityChoices.IFRC_NS) & ~Q(countries__id__in=user_countries))
                             .get(pk=pk)
                         )
                 else:
-                    instance = Event.objects.filter(visibility=VisibilityChoices.PUBLIC).get(pk=pk)
+                    instance = (
+                        Event.objects.prefetch_related(FR)
+                        .filter(visibility=VisibilityChoices.PUBLIC)
+                        .get(pk=pk)
+                    )
                 # instance = Event.get_for(request.user).get(pk=pk)
             except Exception:
                 raise Http404
diff --git a/api/serializers.py b/api/serializers.py
index e950931ece..8bce833dbd 100644
--- a/api/serializers.py
+++ b/api/serializers.py
@@ -843,8 +843,8 @@ class Meta:
 
 
 class MiniFieldReportSerializer(ModelSerializer):
-    contacts = FieldReportContactSerializer(many=True)
-    countries = MiniCountrySerializer(many=True)
+    contacts = FieldReportContactSerializer(many=True, read_only=True)
+    countries = MiniCountrySerializer(many=True, read_only=True)
     epi_figures_source_display = serializers.CharField(source="get_epi_figures_source_display", read_only=True)
     visibility_display = serializers.CharField(source="get_visibility_display", read_only=True)