Add discussion topic API

This is the first stage of the new Discussion API.

JIRA: MA-604

lms/djangoapps/discussion_api/api.py

+"""
+Discussion API internal interface
+"""
+from collections import defaultdict
+
+from django_comment_client.utils import get_accessible_discussion_modules
+
+
+def get_course_topics(course, user):
+    """
+    Return the course topic listing for the given course and user.
+
+    Parameters:
+
+    course: The course to get topics for
+    user: The requesting user, for access control
+
+    Returns:
+
+    A course topic listing dictionary; see discussion_api.views.CourseTopicViews
+    for more detail.
+    """
+    def get_module_sort_key(module):
+        """
+        Get the sort key for the module (falling back to the discussion_target
+        setting if absent)
+        """
+        return module.sort_key or module.discussion_target
+
+    discussion_modules = get_accessible_discussion_modules(course, user)
+    modules_by_category = defaultdict(list)
+    for module in discussion_modules:
+        modules_by_category[module.discussion_category].append(module)
+    courseware_topics = [
+        {
+            "id": None,
+            "name": category,
+            "children": [
+                {
+                    "id": module.discussion_id,
+                    "name": module.discussion_target,
+                    "children": [],
+                }
+                for module in sorted(modules_by_category[category], key=get_module_sort_key)
+            ],
+        }
+        for category in sorted(modules_by_category.keys())
+    ]
+
+    non_courseware_topics = [
+        {
+            "id": entry["id"],
+            "name": name,
+            "children": [],
+        }
+        for name, entry in sorted(
+            course.discussion_topics.items(),
+            key=lambda item: item[1].get("sort_key", item[0])
+        )
+    ]
+
+    return {
+        "courseware_topics": courseware_topics,
+        "non_courseware_topics": non_courseware_topics,
+    }

lms/djangoapps/discussion_api/models.py

+"""
+A models.py is required to make this an app (until we move to Django 1.7)
+"""

lms/djangoapps/discussion_api/tests/test_views.py

+"""
+Tests for Discussion API views
+"""
+from datetime import datetime
+import json
+
+import mock
+from pytz import UTC
+
+from django.core.urlresolvers import reverse
+
+from student.tests.factories import CourseEnrollmentFactory, UserFactory
+from util.testing import UrlResetMixin
+from xmodule.modulestore.django import modulestore
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
+from xmodule.modulestore.tests.factories import CourseFactory
+from xmodule.tabs import DiscussionTab
+
+
+class CourseTopicsViewTest(UrlResetMixin, ModuleStoreTestCase):
+    """Tests for CourseTopicsView"""
+
+    @mock.patch.dict("django.conf.settings.FEATURES", {"ENABLE_DISCUSSION_SERVICE": True})
+    def setUp(self):
+        super(CourseTopicsViewTest, self).setUp()
+        self.maxDiff = None  # pylint: disable=invalid-name
+        self.course = CourseFactory.create(
+            org="x",
+            course="y",
+            run="z",
+            start=datetime.now(UTC),
+            discussion_topics={"Test Topic": {"id": "test_topic"}}
+        )
+        self.password = "password"
+        self.user = UserFactory.create(password=self.password)
+        CourseEnrollmentFactory.create(user=self.user, course_id=self.course.id)
+        self.url = reverse("course_topics", kwargs={"course_id": unicode(self.course.id)})
+        self.client.login(username=self.user.username, password=self.password)
+
+    def assert_response_correct(self, response, expected_status, expected_content):
+        """
+        Assert that the response has the given status code and parsed content
+        """
+        self.assertEqual(response.status_code, expected_status)
+        parsed_content = json.loads(response.content)
+        self.assertEqual(parsed_content, expected_content)
+
+    def test_not_authenticated(self):
+        self.client.logout()
+        response = self.client.get(self.url)
+        self.assert_response_correct(
+            response,
+            401,
+            {"developer_message": "Authentication credentials were not provided."}
+        )
+
+    def test_non_existent_course(self):
+        response = self.client.get(
+            reverse("course_topics", kwargs={"course_id": "non/existent/course"})
+        )
+        self.assert_response_correct(
+            response,
+            404,
+            {"developer_message": "Not found."}
+        )
+
+    def test_not_enrolled(self):
+        unenrolled_user = UserFactory.create(password=self.password)
+        self.client.login(username=unenrolled_user.username, password=self.password)
+        response = self.client.get(self.url)
+        self.assert_response_correct(
+            response,
+            404,
+            {"developer_message": "Not found."}
+        )
+
+    def test_discussions_disabled(self):
+        self.course.tabs = [tab for tab in self.course.tabs if not isinstance(tab, DiscussionTab)]
+        modulestore().update_item(self.course, self.user.id)
+        response = self.client.get(self.url)
+        self.assert_response_correct(
+            response,
+            404,
+            {"developer_message": "Not found."}
+        )
+
+    def test_get(self):
+        response = self.client.get(self.url)
+        self.assert_response_correct(
+            response,
+            200,
+            {
+                "courseware_topics": [],
+                "non_courseware_topics": [{
+                    "id": "test_topic",
+                    "name": "Test Topic",
+                    "children": []
+                }],
+            }
+        )

lms/djangoapps/discussion_api/urls.py

+"""
+Discussion API URLs
+"""
+from django.conf import settings
+from django.conf.urls import patterns, url
+
+from discussion_api.views import CourseTopicsView
+
+
+urlpatterns = patterns(
+    "discussion_api",
+    url(
+        r"^v1/course_topics/{}".format(settings.COURSE_ID_PATTERN),
+        CourseTopicsView.as_view(),
+        name="course_topics"
+    ),
+)

lms/djangoapps/discussion_api/views.py

+"""
+Discussion API views
+"""
+from django.http import Http404
+
+from rest_framework.authentication import OAuth2Authentication, SessionAuthentication
+from rest_framework.permissions import IsAuthenticated
+from rest_framework.response import Response
+from rest_framework.views import APIView
+
+from opaque_keys.edx.locator import CourseLocator
+
+from courseware.courses import get_course_with_access
+from discussion_api.api import get_course_topics
+from openedx.core.lib.api.view_utils import DeveloperErrorViewMixin
+from xmodule.tabs import DiscussionTab
+
+
+class CourseTopicsView(DeveloperErrorViewMixin, APIView):
+    """
+    **Use Cases**
+
+        Retrieve the topic listing for a course. Only topics accessible to the
+        authenticated user are included.
+
+    **Example Requests**:
+
+        GET /api/discussion/v1/course_topics/{course_id}
+
+    **Response Values**:
+
+        * courseware_topics: The list of topic trees for courseware-linked
+          topics. Each item in the list includes:
+
+            * id: The id of the discussion topic (null for a topic that only
+              has children but cannot contain threads itself).
+
+            * name: The display name of the topic.
+
+            * children: A list of child subtrees of the same format.
+
+        * non_courseware_topics: The list of topic trees that are not linked to
+              courseware. Items are of the same format as in courseware_topics.
+    """
+    authentication_classes = (OAuth2Authentication, SessionAuthentication)
+    permission_classes = (IsAuthenticated,)
+
+    def get(self, request, course_id):
+        """Implements the GET method as described in the class docstring."""
+        course_key = CourseLocator.from_string(course_id)
+        course = get_course_with_access(request.user, 'load_forum', course_key)
+        if not any([isinstance(tab, DiscussionTab) for tab in course.tabs]):
+            raise Http404
+        return Response(get_course_topics(course, request.user))

lms/envs/common.py

@@ -1657,6 +1657,7 @@ INSTALLED_APPS = (
     # Discussion forums
     'django_comment_client',
     'django_comment_common',
+    'discussion_api',
     'notes',
 
     'edxnotes',

lms/urls.py

@@ -443,6 +443,7 @@ if settings.COURSEWARE_ENABLED:
     # discussion forums live within courseware, so courseware must be enabled first
     if settings.FEATURES.get('ENABLE_DISCUSSION_SERVICE'):
         urlpatterns += (
+            url(r'^api/discussion/', include('discussion_api.urls')),
             url(r'^courses/{}/discussion/'.format(settings.COURSE_ID_PATTERN),
                 include('django_comment_client.urls')),
             url(r'^notification_prefs/enable/', 'notification_prefs.views.ajax_enable'),

openedx/core/lib/api/view_utils.py

+"""
+Utilities related to API views
+"""
+from django.http import Http404
+
+from rest_framework.exceptions import APIException
+from rest_framework.response import Response
+
+
+class DeveloperErrorViewMixin(object):
+    """
+    A view mixin to handle common error cases other than validation failure
+    (auth failure, method not allowed, etc.) by generating an error response
+    conforming to our API conventions with a developer message.
+    """
+    def make_error_response(self, status_code, developer_message):
+        """
+        Build an error response with the given status code and developer_message
+        """
+        return Response({"developer_message": developer_message}, status=status_code)
+
+    def handle_exception(self, exc):
+        if isinstance(exc, APIException):
+            return self.make_error_response(exc.status_code, exc.detail)
+        elif isinstance(exc, Http404):
+            return self.make_error_response(404, "Not found.")
+        else:
+            raise