refactor(invitations): insert invitations one at a time

src/Handler/Utils/Invitations.hs

@@ -175,7 +175,7 @@ sinkInvitations :: forall junction.
 -- updated, instead.
 --
 -- For new junctions an invitation is sent by e-mail.
-sinkInvitations InvitationConfig{..} = determineExists .| C.foldMap pure >>= lift . sinkInvitations'
+sinkInvitations InvitationConfig{..} = determineExists .| sinkInvitations'
   where
     determineExists :: Conduit (Invitation' junction)
                                (YesodJobDB UniWorX)
@@ -201,13 +201,9 @@ sinkInvitations InvitationConfig{..} = determineExists .| C.foldMap pure >>= lif
               JSON.Success dbData -> return dbData
               JSON.Error   str    -> fail $ "Could not decode invitationData: " <> str
 
-    sinkInvitations' :: [Invitation' junction]
-                     -> YesodJobDB UniWorX ()
-    sinkInvitations' new = do
-      when (is _Nothing (ephemeralInvitation @junction)) $ do
-        insertMany_ $ map (\(email, fid, dat) -> Invitation email (invRef @junction fid) (toJSON $ dat ^. _invitationDBData)) new
-        -- forM_ existing $ \(iid, oldDat) -> update iid [ InvitationData =. toJSON (dat ^. _invitationDBData) ]
-      forM_ new $ \(jInvitee, fid, dat) -> do
+    sinkInvitations' :: Sink (Invitation' junction) (YesodJobDB UniWorX) ()
+    sinkInvitations' = do
+      C.mapM_ $ \(jInvitee, fid, dat) -> do
         app <- getYesod
         let mr = renderMessage app $ NonEmpty.toList appLanguages
         ur <- getUrlRenderParams
@@ -224,6 +220,8 @@ sinkInvitations InvitationConfig{..} = determineExists .| C.foldMap pure >>= lif
         jInvitationSubject <- fmap mr . mapReaderT liftHandlerT $ invitationSubject fEnt dat
         let jInvitationExplanation = invitationExplanation fEnt dat (toHtml . mr) ur
 
+        when (is _Nothing (ephemeralInvitation @junction)) $ insert_ $ Invitation jInvitee (invRef @junction fid) (toJSON $ dat ^. _invitationDBData)
+
         queueDBJob JobInvitation{..}
 
 sinkInvitationsF :: forall junction mono.