From 174c01759fafd6c8984479f7a445b140b4478618 Mon Sep 17 00:00:00 2001
From: Simon Chen <schen@edx.org>
Date: Mon, 30 Apr 2018 11:54:10 -0400
Subject: [PATCH] Implement retire users function in the SurveyAnswer model for
 GDPR

---
 lms/djangoapps/survey/models.py            | 18 ++++++++++++++--
 lms/djangoapps/survey/tests/test_models.py | 25 ++++++++++++++++++++++
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/lms/djangoapps/survey/models.py b/lms/djangoapps/survey/models.py
index a69935bf38..8e6d684383 100644
--- a/lms/djangoapps/survey/models.py
+++ b/lms/djangoapps/survey/models.py
@@ -239,8 +239,6 @@ class SurveyAnswer(TimeStampedModel):
         supplied to this method is presumed to be previously validated
         """
         for name in answers.keys():
-            value = answers[name]
-
             # See if there is an answer stored for this user, form, field_name pair or not
             # this will allow for update cases. This does include an additional lookup,
             # but write operations will be relatively infrequent
@@ -261,3 +259,19 @@ class SurveyAnswer(TimeStampedModel):
                 answer.field_value = value
                 answer.course_key = course_key
                 answer.save()
+
+    @classmethod
+    def retire_user(cls, user_id):
+        """
+        With the parameter user_id, blank out the survey answer values for all survey questions
+        This is to fulfill our GDPR obligations
+
+        Return True if there are data to be blanked
+        Return False if there are no matching data
+        """
+        answers = cls.objects.filter(user=user_id)
+        if not answers:
+            return False
+
+        answers.update(field_value='')
+        return True
diff --git a/lms/djangoapps/survey/tests/test_models.py b/lms/djangoapps/survey/tests/test_models.py
index 1c286e6055..65deb20c0a 100644
--- a/lms/djangoapps/survey/tests/test_models.py
+++ b/lms/djangoapps/survey/tests/test_models.py
@@ -280,3 +280,28 @@ class SurveyModelsTests(TestCase):
         names = survey.get_field_names()
 
         self.assertEqual(sorted(names), ['ddl', 'field1', 'field2'])
+
+    def test_retire_user_successful(self):
+        survey = self._create_test_survey()
+        self.assertIsNotNone(survey)
+
+        survey.save_user_answers(self.student, self.student_answers, self.course_id)
+        survey.save_user_answers(self.student2, self.student2_answers, self.course_id)
+
+        retire_result = SurveyAnswer.retire_user(self.student.id)
+        self.assertTrue(retire_result)
+        answers = survey.get_answers(self.student)
+        blanked_out_student_answser = {key: '' for key in self.student_answers}
+        self.assertEquals(answers[self.student.id], blanked_out_student_answser)
+        self.assertEquals(survey.get_answers(self.student2)[self.student2.id], self.student2_answers)
+
+    def test_retire_user_not_exist(self):
+        survey = self._create_test_survey()
+        self.assertIsNotNone(survey)
+
+        survey.save_user_answers(self.student, self.student_answers, self.course_id)
+
+        retire_result = SurveyAnswer.retire_user(self.student2.id)
+        self.assertFalse(retire_result)
+        answers = survey.get_answers(self.student)
+        self.assertEquals(answers[self.student.id], self.student_answers)