From 15d8793fe3f24b723d04d6b2d15e1d603927e606 Mon Sep 17 00:00:00 2001
From: Alejandro Alonso <alejandroalonsofernandez@gmail.com>
Date: Fri, 18 Dec 2015 09:20:48 +0100
Subject: [PATCH] [Backport] Improving milestones API a bit more

---
 taiga/projects/milestones/api.py         | 31 +++++++++++++++++++-----
 taiga/projects/milestones/serializers.py | 27 +--------------------
 2 files changed, 26 insertions(+), 32 deletions(-)

diff --git a/taiga/projects/milestones/api.py b/taiga/projects/milestones/api.py
index 056ed7d3..94cb04ec 100644
--- a/taiga/projects/milestones/api.py
+++ b/taiga/projects/milestones/api.py
@@ -15,6 +15,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 from django.apps import apps
+from django.db.models import Prefetch
 
 from taiga.base import filters
 from taiga.base import response
@@ -25,6 +26,8 @@ from taiga.base.utils.db import get_object_or_none
 
 from taiga.projects.notifications.mixins import WatchedResourceMixin, WatchersViewSetMixin
 from taiga.projects.history.mixins import HistoryResourceMixin
+from taiga.projects.votes.utils import attach_total_voters_to_queryset, attach_is_voter_to_queryset
+from taiga.projects.notifications.utils import attach_watchers_to_queryset, attach_is_watcher_to_queryset
 
 from . import serializers
 from . import models
@@ -62,14 +65,30 @@ class MilestoneViewSet(HistoryResourceMixin, WatchedResourceMixin, ModelCrudView
 
     def get_queryset(self):
         qs = super().get_queryset()
-        qs = qs.prefetch_related("user_stories",
-                                 "user_stories__role_points",
-                                 "user_stories__role_points__points",
-                                 "user_stories__role_points__role")
 
-        qs = qs.select_related("project",
-                               "owner")
+        # Userstories prefetching
+        UserStory = apps.get_model("userstories", "UserStory")
+        us_qs = UserStory.objects.prefetch_related("role_points",
+                                                   "role_points__points",
+                                                   "role_points__role")
 
+        us_qs = us_qs.select_related("milestone",
+                                     "project",
+                                     "status",
+                                     "owner",
+                                     "assigned_to",
+                                     "generated_from_issue")
+
+        us_qs = self.attach_watchers_attrs_to_queryset(us_qs)
+
+        if self.request.user.is_authenticated():
+            us_qs = attach_is_voter_to_queryset(self.request.user, us_qs)
+            us_qs = attach_is_watcher_to_queryset(self.request.user, us_qs)
+
+        qs = qs.prefetch_related(Prefetch("user_stories", queryset=us_qs))
+
+        # Milestones prefetching
+        qs = qs.select_related("project", "owner")
         qs = self.attach_watchers_attrs_to_queryset(qs)
 
         qs = qs.order_by("-estimated_start")
diff --git a/taiga/projects/milestones/serializers.py b/taiga/projects/milestones/serializers.py
index a622ea0f..5d3ddf7b 100644
--- a/taiga/projects/milestones/serializers.py
+++ b/taiga/projects/milestones/serializers.py
@@ -20,15 +20,13 @@ from taiga.base.api import serializers
 from taiga.base.utils import json
 from taiga.projects.notifications.mixins import WatchedResourceModelSerializer
 from taiga.projects.notifications.validators import WatchersValidator
-from taiga.projects.votes.utils import attach_total_voters_to_queryset, attach_is_voter_to_queryset
-from taiga.projects.notifications.utils import attach_watchers_to_queryset, attach_is_watcher_to_queryset
 
 from ..userstories.serializers import UserStoryListSerializer
 from . import models
 
 
 class MilestoneSerializer(WatchersValidator, WatchedResourceModelSerializer, serializers.ModelSerializer):
-    user_stories = serializers.SerializerMethodField("get_user_stories")
+    user_stories = UserStoryListSerializer(many=True, required=False, read_only=True)
     total_points = serializers.SerializerMethodField("get_total_points")
     closed_points = serializers.SerializerMethodField("get_closed_points")
 
@@ -36,29 +34,6 @@ class MilestoneSerializer(WatchersValidator, WatchedResourceModelSerializer, ser
         model = models.Milestone
         read_only_fields = ("id", "created_date", "modified_date")
 
-    def get_user_stories(self, obj):
-        qs = obj.user_stories.prefetch_related("role_points",
-                                               "role_points__points",
-                                               "role_points__role")
-
-        qs = qs.select_related("milestone",
-                               "project",
-                               "status",
-                               "owner",
-                               "assigned_to",
-                               "generated_from_issue")
-
-        request = self.context.get("request", None)
-        requesting_user = request and request.user or None
-        if requesting_user and requesting_user.is_authenticated():
-            qs = attach_is_voter_to_queryset(requesting_user, qs)
-            qs = attach_is_watcher_to_queryset(requesting_user, qs)
-
-        qs = attach_total_voters_to_queryset(qs)
-        qs = attach_watchers_to_queryset(qs)
-
-        return UserStoryListSerializer(qs, many=True).data
-
     def get_total_points(self, obj):
         return sum(obj.total_points.values())