Query optimization for buddy and pickup systems (#290)

Fixes for 1+n queries detected by sentry on /buddy-system/my-buddies and
/pickup-system/matching-requests.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

- **New Features**
- Enhanced data retrieval for user buddy matches in the MyBuddies view,
improving efficiency.
- Optimized matching requests handling in the pickup system for better
performance.

- **Bug Fixes**
- Improved the lookup for primary email addresses in user profiles,
ensuring accuracy and efficiency.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

fiesta/apps/accounts/models/user.py

@@ -56,7 +56,7 @@ class Meta(AbstractUser.Meta):
 
     @property
     def primary_email(self):
-        return self.emailaddress_set.filter(primary=True).first() or self.email
+        return next((email for email in self.emailaddress_set.all() if email.primary), self.email)
 
 
 __all__ = ["User"]

fiesta/apps/buddy_system/views/matches.py

@@ -18,9 +18,13 @@ class MyBuddies(EnsureLocalUserViewMixin, ListView):
 
     def get_queryset(self):
         return (
-            self.request.user.buddy_system_request_matches.prefetch_related("request__issuer__profile")
-            .select_related("request", "matcher")
-            .filter(
-                request__state=BaseRequestProtocol.State.MATCHED,
+            self.request.user.buddy_system_request_matches.prefetch_related(
+                "request__issuer__emailaddress_set",
             )
+            .select_related(
+                "request__issuer__profile__user",
+                "request__issuer__profile__university",
+                "request__issuer__profile__faculty",
+            )
+            .filter(request__state=BaseRequestProtocol.State.MATCHED)
         )

fiesta/apps/buddy_system/views/matching.py

@@ -47,7 +47,12 @@ def get_permission_denied_message(self):
 
     def get_queryset(self):
         return self.configuration.matching_policy_instance.limit_requests(
-            qs=BuddyRequest.objects.get_queryset(),
+            qs=BuddyRequest.objects.get_queryset().select_related(
+                # select all potentially necessary fields in the template afterward
+                "issuer__profile__user",
+                "issuer__profile__university",
+                "issuer__profile__faculty",
+            ),
             membership=self.request.membership,
         )
 

fiesta/apps/pickup_system/views/matches.py

@@ -18,8 +18,12 @@ class MyPickups(EnsureLocalUserViewMixin, ListView):
 
     def get_queryset(self):
         return (
-            self.request.user.pickup_system_request_matches.prefetch_related("request__issuer__profile")
-            .select_related("request", "matcher")
+            self.request.user.pickup_system_request_matches.prefetch_related("request__issuer__emailaddress_set")
+            .select_related(
+                "request__issuer__profile__user",
+                "request__issuer__profile__university",
+                "request__issuer__profile__faculty",
+            )
             .filter(
                 request__state=BaseRequestProtocol.State.MATCHED,
             )

fiesta/apps/pickup_system/views/matching.py

@@ -31,7 +31,11 @@ class MatchingRequestsView(
     model = PickupRequest
 
     def get_queryset(self):
-        return self.request.in_space_of_section.pickup_system_requests.filter(
+        return self.request.in_space_of_section.pickup_system_requests.select_related(
+            "issuer__profile__user",
+            "issuer__profile__university",
+            "issuer__profile__faculty",
+        ).filter(
             state=PickupRequest.State.CREATED,
         )