[#2507] Fix broken pagination on subclasses of PublicProjectViewSet

Not ensuring that `.distinct` is called on the queryset used by subclasses of
`PublicProjectViewSet` caused a bug where an indicator period was missing from
the results page of a project.  This commit fixes that bug.

This commit comes with a simple test, but the test isn't actually able to
reproduce the bug on production.  Not sure what exactly needs to be done to
reproduce that bug.

akvo/rest/viewsets.py

@@ -139,13 +139,13 @@ def get_queryset(self):
         if user.is_anonymous() or not (user.is_superuser or user.is_admin):
             queryset = self.projects_filter_for_non_privileged_users(user, queryset, self.project_relation)
 
-        return queryset
+        return queryset.distinct()
 
     @staticmethod
     def projects_filter_for_non_privileged_users(user, queryset, project_relation):
 
         if not user.is_anonymous() and (user.is_admin or user.is_superuser):
-            return queryset
+            return queryset.distinct()
 
         # Construct the public projects filter field lookup.
         project_filter = project_relation + 'is_public'
@@ -165,4 +165,4 @@ def projects_filter_for_non_privileged_users(user, queryset, project_relation):
             filter_ = user.get_permission_filter(permission, project_relation)
             queryset = public_objects | private_objects.filter(filter_).distinct()
 
-        return queryset
+        return queryset.distinct()

akvo/rsr/tests/rest/test_indicator.py

@@ -0,0 +1,105 @@
+# -*- coding: utf-8 -*-
+
+"""
+Akvo RSR is covered by the GNU Affero General Public License.
+
+See more details in the license.txt file located at the root folder of the Akvo RSR module.
+For additional details on the GNU license please see < http://www.gnu.org/licenses/agpl.html >.
+"""
+
+import json
+
+from django.conf import settings
+from django.contrib.auth.models import Group
+from django.test import TestCase, Client
+
+from akvo.rsr.models import Project, Organisation, Partnership, User, Employment, Result, Indicator, IndicatorPeriod
+from akvo.utils import check_auth_groups
+
+
+class RestIndicatorTestCase(TestCase):
+    """Tests the indicator REST endpoints."""
+
+    def setUp(self):
+        """ Setup a minimal DB for the tests. """
+
+        self.project = Project.objects.create(
+            title="REST test project",
+        )
+
+        # Create groups
+        check_auth_groups(settings.REQUIRED_AUTH_GROUPS)
+
+        # Create organisation
+        self.reporting_org = Organisation.objects.create(
+            id=1337,
+            name="Test REST reporting",
+            long_name="Test REST reporting org",
+            new_organisation_type=22
+        )
+
+        # Create partnership
+        self.partnership = Partnership.objects.create(
+            project=self.project,
+            organisation=self.reporting_org,
+            iati_organisation_role=Partnership.IATI_REPORTING_ORGANISATION,
+        )
+
+        # Create active user
+        self.user = User.objects.create_user(
+            username="Normal user REST",
+            email="user.rest@test.akvo.org",
+            password="password",
+        )
+        self.user.is_active = True
+        self.user.is_admin = True
+        self.user.is_superuser = True
+        self.user.save()
+
+        # Create employment
+        self.employment = Employment.objects.create(
+            user=self.user,
+            organisation=self.reporting_org,
+            is_approved=True,
+        )
+
+        self.c = Client(HTTP_HOST=settings.RSR_DOMAIN)
+
+    def tearDown(self):
+        Project.objects.all().delete()
+        User.objects.all().delete()
+        Organisation.objects.all().delete()
+        Group.objects.all().delete()
+
+    def test_rest_indicator_pagination(self):
+        """Test that paginating the indicator results works."""
+
+        # Given
+        n_results = 5
+        n_indicators = 5
+        n_periods = 6
+        total = n_results * n_indicators * n_periods
+        for _ in range(n_results):
+            result = Result.objects.create(project=self.project)
+            for _ in range(n_indicators):
+                indicator = Indicator.objects.create(result=result)
+                for _ in range(n_periods):
+                    IndicatorPeriod.objects.create(indicator=indicator)
+
+        self.c.login(username=self.user.username, password="password")
+
+        indicator_periods = self.get_indicator_periods(self.project.id)
+        self.assertEqual(len(indicator_periods), total)
+        for indicator_id in Indicator.objects.values_list('id', flat=True):
+            periods = filter(lambda x: x['indicator'] == indicator_id, indicator_periods)
+            self.assertEqual(len(periods), n_periods)
+
+    def get_indicator_periods(self, project_id):
+        periods = []
+        next_url = '/rest/v1/indicator_period/?format=json&indicator__result__project={}&limit=50'.format(project_id)
+        while next_url:
+            response = self.c.get(next_url)
+            data = json.loads(response.content)
+            periods += data['results']
+            next_url = data['next']
+        return periods