From c4ee7dacbce38ab607305c8579f7d5d0e567d5be Mon Sep 17 00:00:00 2001
From: bmedx <bmesick@edx.org>
Date: Wed, 8 Aug 2018 09:44:24 -0400
Subject: [PATCH] Update retirement to handle multiple UserRetirementStatus
 rows returned

---
 .../djangoapps/user_api/accounts/views.py     | 41 +++++++++++++++++--
 openedx/core/djangoapps/user_api/models.py    | 17 +++++++-
 2 files changed, 54 insertions(+), 4 deletions(-)

diff --git a/openedx/core/djangoapps/user_api/accounts/views.py b/openedx/core/djangoapps/user_api/accounts/views.py
index 0d0d26c7cb..6980a737b0 100644
--- a/openedx/core/djangoapps/user_api/accounts/views.py
+++ b/openedx/core/djangoapps/user_api/accounts/views.py
@@ -624,9 +624,23 @@ class AccountRetirementPartnerReportView(ViewSet):
             original_username__in=usernames
         )
 
-        if len(usernames) != len(retirement_statuses):
+        # Need to de-dupe usernames that differ only by case to find the exact right match
+        retirement_statuses_clean = [rs for rs in retirement_statuses if rs.original_username in usernames]
+
+        # During a narrow window learners were able to re-use a username that had been retired if
+        # they altered the capitalization of one or more characters. Therefore we can have more
+        # than one row returned here (due to our MySQL collation being case-insensitive), and need
+        # to disambiguate them in Python, which will respect case in the comparison.
+        if len(usernames) != len(retirement_statuses_clean):
             return Response(
-                '{} original_usernames given, only {} found!'.format(len(usernames), len(retirement_statuses)),
+                '{} original_usernames given, {} found!\n'
+                'Given usernames:\n{}\n'
+                'Found UserRetirementReportingStatuses:\n{}'.format(
+                    len(usernames),
+                    len(retirement_statuses_clean),
+                    usernames,
+                    ', '.join([rs.original_username for rs in retirement_statuses_clean])
+                ),
                 status=status.HTTP_400_BAD_REQUEST
             )
 
@@ -765,7 +779,28 @@ class AccountRetirementStatusView(ViewSet):
         """
         try:
             username = request.data['username']
-            retirement = UserRetirementStatus.objects.get(original_username=username)
+            retirements = UserRetirementStatus.objects.filter(original_username=username)
+
+            # During a narrow window learners were able to re-use a username that had been retired if
+            # they altered the capitalization of one or more characters. Therefore we can have more
+            # than one row returned here (due to our MySQL collation being case-insensitive), and need
+            # to disambiguate them in Python, which will respect case in the comparison.
+            retirement = None
+            if len(retirements) < 1:
+                raise UserRetirementStatus.DoesNotExist()
+            elif len(retirements) > 1:
+                for r in retirements:
+                    if r.original_username == username:
+                        retirement = r
+                        break
+                # UserRetirementStatus was found, but it was the wrong case.
+                if retirement is None:
+                    raise UserRetirementStatus.DoesNotExist()
+            else:
+                if username != retirements[0].original_username:
+                    raise UserRetirementStatus.DoesNotExist()
+                retirement = retirements[0]
+
             retirement.update_state(request.data)
             return Response(status=status.HTTP_204_NO_CONTENT)
         except UserRetirementStatus.DoesNotExist:
diff --git a/openedx/core/djangoapps/user_api/models.py b/openedx/core/djangoapps/user_api/models.py
index dca0eb6aba..882a3ef508 100644
--- a/openedx/core/djangoapps/user_api/models.py
+++ b/openedx/core/djangoapps/user_api/models.py
@@ -335,7 +335,22 @@ class UserRetirementStatus(TimeStampedModel):
         Can raise UserRetirementStatus.DoesNotExist or RetirementStateError, otherwise should
         return a UserRetirementStatus
         """
-        retirement = cls.objects.get(original_username=username)
+        # During a narrow window learners were able to re-use a username that had been retired if
+        # they altered the capitalization of one or more characters. Therefore we can have more
+        # than one row returned here (due to our MySQL collation being case-insensitive), and need
+        # to disambiguate them in Python, which will respect case in the comparison.
+        retirements = cls.objects.filter(original_username=username)
+
+        retirement = None
+        for r in retirements:
+            if r.original_username == username:
+                retirement = r
+                break
+
+        if retirement is None:
+            raise UserRetirementStatus.DoesNotExist('{} does not have an exact match in UserRetirementStatus. '
+                                                    '{} similar rows found.'.format(username, len(retirements)))
+
         state = retirement.current_state
 
         if state.required or state.state_name.endswith('_COMPLETE'):