Optimize alert and alert group public api endpoints, add filter by id (#1274)

# What this PR does

## Which issue(s) this PR fixes

## Checklist

- [ ] Tests updated
- [ ] Documentation added
- [ ] `CHANGELOG.md` updated

---------

Co-authored-by: Joey Orlando <joey.orlando@grafana.com>

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Added
+
+- Optimize alert and alert group public api endpoints and add filter by id ([1274](https://github.com/grafana/oncall/pull/1274)
+
 ## v1.1.21 (2023-02-02)
 
 ### Added
@@ -12,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add [`django-dbconn-retry` library](https://github.com/jdelic/django-dbconn-retry) to `INSTALLED_APPS` to attempt
   to alleviate occasional `django.db.utils.OperationalError` errors
 - Improve alerts and alert group endpoint response time in internal API with caching ([1261](https://github.com/grafana/oncall/pull/1261))
+- Optimize alert and alert group public api endpoints and add filter by id ([1274](https://github.com/grafana/oncall/pull/1274)
 - Added Coming Soon for iOS on Mobile App screen
 
 ### Fixed

docs/sources/oncall-api-reference/alertgroups.md

@@ -44,6 +44,7 @@ The above command returns JSON structured in the following way:
 
 These available filter parameters should be provided as `GET` arguments:
 
+- `id`
 - `route_id`
 - `integration_id`
 - `state`

docs/sources/oncall-api-reference/alerts.md

@@ -104,6 +104,7 @@ The above command returns JSON structured in the following way:
 
 The following available filter parameters should be provided as `GET` arguments:
 
+- `id`
 - `alert_group_id`
 - `search`—string-based inclusion search by alert payload
 

engine/apps/public_api/serializers/incidents.py

@@ -13,12 +13,11 @@ class IncidentSerializer(EagerLoadingMixin, serializers.ModelSerializer):
     route_id = serializers.SerializerMethodField()
     created_at = serializers.DateTimeField(source="started_at")
     alerts_count = serializers.SerializerMethodField()
-    title = serializers.SerializerMethodField()
+    title = serializers.CharField(source="web_title_cache")
     state = serializers.SerializerMethodField()
 
-    SELECT_RELATED = ["channel", "channel_filter", "slack_message"]
+    SELECT_RELATED = ["channel", "channel_filter", "slack_message", "channel__organization"]
     PREFETCH_RELATED = [
-        "alerts",
         Prefetch(
             "telegram_messages",
             TelegramMessage.objects.filter(chat_id__startswith="-", message_type=TelegramMessage.ALERT_GROUP_MESSAGE),
@@ -42,10 +41,8 @@ class IncidentSerializer(EagerLoadingMixin, serializers.ModelSerializer):
         ]
 
     def get_alerts_count(self, obj):
-        return len(obj.alerts.all())
-
-    def get_title(self, obj):
-        return obj.alerts.all()[0].title
+        # alerts_count is an annotated field added in get_queryset
+        return obj.alerts_count
 
     def get_state(self, obj):
         return obj.state

engine/apps/public_api/views/alerts.py

@@ -1,5 +1,6 @@
 from django.db.models import CharField
 from django.db.models.functions import Cast
+from django_filters import rest_framework as filters
 from rest_framework import mixins
 from rest_framework.permissions import IsAuthenticated
 from rest_framework.viewsets import GenericViewSet
@@ -12,6 +13,10 @@ from common.api_helpers.mixins import RateLimitHeadersMixin
 from common.api_helpers.paginators import FiftyPageSizePaginator
 
 
+class AlertFilter(filters.FilterSet):
+    id = filters.CharFilter(field_name="public_primary_key")
+
+
 class AlertView(RateLimitHeadersMixin, mixins.ListModelMixin, GenericViewSet):
     authentication_classes = (ApiTokenAuthentication,)
     permission_classes = (IsAuthenticated,)
@@ -22,6 +27,9 @@ class AlertView(RateLimitHeadersMixin, mixins.ListModelMixin, GenericViewSet):
     serializer_class = AlertSerializer
     pagination_class = FiftyPageSizePaginator
 
+    filter_backends = (filters.DjangoFilterBackend,)
+    filterset_class = AlertFilter
+
     def get_queryset(self):
         alert_group_id = self.request.query_params.get("alert_group_id", None)
         search = self.request.query_params.get("search", None)

engine/apps/public_api/views/incidents.py

@@ -1,4 +1,4 @@
-from django.db.models import Q
+from django.db.models import Count, Q
 from django_filters import rest_framework as filters
 from rest_framework import mixins, status
 from rest_framework.exceptions import NotFound
@@ -29,6 +29,8 @@ class IncidentByTeamFilter(ByTeamModelFieldFilterMixin, filters.FilterSet):
         method=ByTeamModelFieldFilterMixin.filter_model_field_with_single_value.__name__,
     )
 
+    id = filters.CharFilter(field_name="public_primary_key")
+
 
 class IncidentView(RateLimitHeadersMixin, mixins.ListModelMixin, mixins.DestroyModelMixin, GenericViewSet):
     authentication_classes = (ApiTokenAuthentication,)
@@ -77,7 +79,7 @@ class IncidentView(RateLimitHeadersMixin, mixins.ListModelMixin, mixins.DestroyM
                 raise BadRequest(detail={"state": f"Must be one of the following: {valid_choices_text}"})
 
         queryset = self.serializer_class.setup_eager_loading(queryset)
-
+        queryset = queryset.annotate(alerts_count=Count("alerts"))
         return queryset
 
     def get_object(self):