From d461b1962d62e7fe3c8b348e830f80c7de7ad7f8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20Barrag=C3=A1n=20Merino?=
 <david.barragan@kaleidos.net>
Date: Wed, 27 Jul 2016 13:41:34 +0200
Subject: [PATCH] Add epics to user stories serializers

---
 taiga/projects/userstories/serializers.py |  6 ++++-
 taiga/projects/userstories/utils.py       | 31 ++++++++++++++++++++++-
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/taiga/projects/userstories/serializers.py b/taiga/projects/userstories/serializers.py
index bc977a2e..97fcea42 100644
--- a/taiga/projects/userstories/serializers.py
+++ b/taiga/projects/userstories/serializers.py
@@ -77,9 +77,13 @@ class UserStoryListSerializer(ProjectExtraInfoSerializerMixin,
     total_points = MethodField()
     comment = MethodField()
     origin_issue = OriginIssueSerializer(attr="generated_from_issue")
-
+    epics = MethodField()
     tasks = MethodField()
 
+    def get_epics(self, obj):
+        assert hasattr(obj, "epics_attr"), "instance must have a epics_attr attribute"
+        return obj.epics_attr
+
     def get_milestone_slug(self, obj):
         return obj.milestone.slug if obj.milestone else None
 
diff --git a/taiga/projects/userstories/utils.py b/taiga/projects/userstories/utils.py
index 35456b71..ea7637f4 100644
--- a/taiga/projects/userstories/utils.py
+++ b/taiga/projects/userstories/utils.py
@@ -71,7 +71,7 @@ def attach_tasks(queryset, as_field="tasks_attr"):
     """Attach tasks as json column to each object of the queryset.
 
     :param queryset: A Django user stories queryset object.
-    :param as_field: Attach the role points as an attribute with this name.
+    :param as_field: Attach tasks as an attribute with this name.
 
     :return: Queryset object with the additional `as_field` field.
     """
@@ -99,9 +99,38 @@ def attach_tasks(queryset, as_field="tasks_attr"):
     return queryset
 
 
+def attach_epics(queryset, as_field="epics_attr"):
+    """Attach epics as json column to each object of the queryset.
+
+    :param queryset: A Django user stories queryset object.
+    :param as_field: Attach the epics as an attribute with this name.
+
+    :return: Queryset object with the additional `as_field` field.
+    """
+
+    model = queryset.model
+    sql = """SELECT json_agg(row_to_json(t))
+               FROM (SELECT "epics_epic"."id" AS "id",
+                            "epics_epic"."ref" AS "ref",
+                            "epics_epic"."subject" AS "subject",
+                            "epics_epic"."color" AS "color",
+                            json_build_object('id', "projects_project"."id",
+                                              'name', "projects_project"."name",
+                                              'slug', "projects_project"."slug") AS "project"
+                       FROM "epics_relateduserstory"
+                 INNER JOIN "epics_epic" ON "epics_epic"."id" = "epics_relateduserstory"."epic_id"
+                 INNER JOIN "projects_project" ON "projects_project"."id" = "epics_epic"."project_id"
+                      WHERE "epics_relateduserstory"."user_story_id" = {tbl}.id) t"""
+
+    sql = sql.format(tbl=model._meta.db_table)
+    queryset = queryset.extra(select={as_field: sql})
+    return queryset
+
+
 def attach_extra_info(queryset, user=None, include_attachments=False, include_tasks=False):
     queryset = attach_total_points(queryset)
     queryset = attach_role_points(queryset)
+    queryset = attach_epics(queryset)
 
     if include_attachments:
         queryset = attach_basic_attachments(queryset)