Add a new service to allow Anonymous Users to vote on xblock-poll (#314)

* feat: Add a new service to allow Anonymous Users to vote on xblock-polls

* refactor: remove extra blank lines

* refactor: add tally_updated as return value to vote

lms/djangoapps/courseware/module_render.py

@@ -54,7 +54,7 @@
 from lms.djangoapps.courseware.model_data import DjangoKeyValueStore, FieldDataCache
 from edxmako.shortcuts import render_to_string
 from lms.djangoapps.courseware.field_overrides import OverrideFieldData
-from lms.djangoapps.courseware.services import UserStateService
+from lms.djangoapps.courseware.services import UserStateService, AnonymousUserPollService
 from lms.djangoapps.grades.api import GradesUtilService
 from lms.djangoapps.grades.api import signals as grades_signals
 from lms.djangoapps.lms_xblock.field_data import LmsFieldData
@@ -819,6 +819,7 @@ def rebind_noauth_module_to_user(module, real_user):
             'gating': GatingService(),
             'grade_utils': GradesUtilService(course_id=course_id),
             'user_state': UserStateService(),
+            'anonymous_user_poll': AnonymousUserPollService(),
         },
         get_user_role=lambda: get_user_role(user, course_id),
         descriptor_runtime=descriptor._runtime,  # pylint: disable=protected-access

lms/djangoapps/courseware/services.py

@@ -10,6 +10,9 @@
 from lms.djangoapps.courseware.models import StudentModule
 from student.models import get_user_by_username_or_email
 
+from xblock.reference.plugins import Service
+from lms.djangoapps.courseware.models import XModuleUserStateSummaryField
+
 
 class UserStateService(object):
     """
@@ -39,3 +42,53 @@ def get_state_as_dict(self, username_or_email, block_id):
             return json.loads(student_module.state)
         except StudentModule.DoesNotExist:
             return {}
+
+
+
+
+class AnonymousUserPollService(Service):
+    """
+    Service to allow anonymous users to vote on xblock polls
+    """
+
+    def vote(self, choice, result, usage_id):
+        """
+        Updates the tally in the database for the anonymous users votes on polls
+        Also, clears the dirty fields so the LMS does not try to update as well
+
+        Args:
+            choice (string): The choice of vote selected by user
+            result (dict): The response dictionary to return to frontend
+            usage_id (UsageKey): usage_id of the poll 
+
+        Returns:
+            dict: Return the result to the handler function
+        """
+        tally = self.get_tally(usage_id)
+        # If tally does not exist, do not update and allow the LMS to handle it
+        if not tally:
+            return result, False
+        tally[choice] += 1
+        # Update tally in the db
+        XModuleUserStateSummaryField.objects.filter(usage_id=usage_id, field_name="tally").update(value=json.dumps(tally))
+        result['success'] = True
+        result['can_vote'] = True
+        result['submissions_count'] = 1
+
+        return result, True
+
+    def get_tally(self, usage_id):
+        """
+        Get the tally of the poll from the database
+
+        Args:
+            usage_id (UsageKey): the usage_id of the poll to filter by
+
+        Returns:
+            dict: Tally of the poll that calls this function
+        """
+        query_set = XModuleUserStateSummaryField.objects.filter(usage_id=usage_id, field_name="tally").first()
+        if not query_set:
+            return None
+        # Tally is a dict stored as string, convert to json
+        return json.loads(query_set.value)