requested changes

back/models/notificationSubscription.js

@@ -47,22 +47,16 @@ module.exports = Self => {
     };
 
     async function getUserToModify(notificationId, userFk, models) {
-        if (notificationId != null) {
+        let userToModify = userFk;
+        if (notificationId) {
             const subscription = await models.NotificationSubscription.findById(notificationId);
-            const user = await subscription.userFk;
+            userToModify = subscription.userFk;
+        }
         return await models.Worker.findOne({
             fields: ['id', 'bossFk'],
             where: {
-                    id: user
+                id: userToModify
             }
         });
-        } else {
-            return await models.Worker.findOne({
-                fields: ['id', 'bossFk'],
-                where: {
-                    id: userFk
-                }
-            });
-        }
     }
 };

db/changes/230201/00-uniqueKeyNotificationSubscription.sql

@@ -0,0 +1,4 @@
+ALTER TABLE
+    `util`.`notificationSubscription`
+ADD
+    CONSTRAINT `notificationSubscription_UN` UNIQUE KEY (`notificationFk`, `userFk`);