fix(print): keep print jobs on user merge and lms id deletion

models/print.model

@@ -9,11 +9,11 @@ PrintJob
   file            ByteString      -- stores plain pdf; otherwise use FileContentReference Maybe
   created         UTCTime
   acknowledged    UTCTime Maybe
-  recipient       UserId Maybe          OnDeleteCascade OnUpdateCascade   -- optional as some letters may contain just an address
+  recipient       UserId Maybe          OnDeleteSetNull OnUpdateCascade   -- optional as some letters may contain just an address
   sender          UserId Maybe          OnDeleteSetNull OnUpdateCascade   -- senders and associations are optional
   course          CourseId Maybe        OnDeleteCascade OnUpdateCascade
   qualification   QualificationId Maybe OnDeleteCascade OnUpdateCascade
-  lmsUser         LmsIdent        Maybe OnDeleteCascade OnUpdateCascade   -- allows tracking if recipient has been notified; must be unique  
+  lmsUser         LmsIdent        Maybe OnDeleteSetNull OnUpdateCascade   -- allows tracking if recipient has been notified; must be unique  
   -- UniquePrintJobLmsUser lmsUser -- Note that in fact multiple print jobs per LMS user are possible!
   -- UniquePrintJobApcIdent apcIdent -- TODO: not yet enforced, since LmsIdent is currently used
   deriving Generic

src/Handler/Utils/Users.hs

@@ -847,6 +847,10 @@ assimilateUser newUserId oldUserId = mapReaderT execWriterT $ do
       delete oldQKey
   -- deleteWhere [ QualificationUserUser ==. oldUserId ] -- no longer needed  
 
+  -- PrintJobs
+  updateWhere [ PrintJobRecipient ==. Just oldUserId ] [ PrintJobRecipient =. Just newUserId ]
+  updateWhere [ PrintJobSender    ==. Just oldUserId ] [ PrintJobSender    =. Just newUserId ]
+
   -- Supervision is fully merged
   E.insertSelectWithConflict
     UniqueUserSupervisor