fix(backend): delete follow relations for deleted users (#8805)

* delete follows

* migration-deleted-user-follows

---------

Co-authored-by: Wolfgang Huß <wolle.huss@pjannto.com>

backend/src/db/migrations/20250804140837-delted-user-follows.ts

@@ -0,0 +1,51 @@
+/* eslint-disable @typescript-eslint/no-unsafe-argument */
+
+import { getDriver } from '@db/neo4j'
+
+export const description = 'Delete follow relation for deleted users'
+
+export async function up(_next) {
+  const driver = getDriver()
+  const session = driver.session()
+  const transaction = session.beginTransaction()
+
+  try {
+    // Implement your migration here.
+    await transaction.run(`
+      MATCH (:User {deleted: true})-[follow:FOLLOWS]-(:User)
+      DELETE follow;
+    `)
+    await transaction.commit()
+  } catch (error) {
+    // eslint-disable-next-line no-console
+    console.log(error)
+    await transaction.rollback()
+    // eslint-disable-next-line no-console
+    console.log('rolled back')
+    throw new Error(error)
+  } finally {
+    await session.close()
+  }
+}
+
+export async function down(_next) {
+  const driver = getDriver()
+  const session = driver.session()
+  const transaction = session.beginTransaction()
+
+  try {
+    // cannot be rolled back
+    // Implement your migration here.
+    // await transaction.run(``)
+    // await transaction.commit()
+  } catch (error) {
+    // eslint-disable-next-line no-console
+    console.log(error)
+    await transaction.rollback()
+    // eslint-disable-next-line no-console
+    console.log('rolled back')
+    throw new Error(error)
+  } finally {
+    await session.close()
+  }
+}

backend/src/graphql/resolvers/users.spec.ts

@@ -554,6 +554,40 @@ describe('Delete a User as admin', () => {
           await expect(database.neode.all('SocialMedia')).resolves.toHaveLength(0)
         })
       })
+
+      describe('connected follow relations', () => {
+        beforeEach(async () => {
+          const userIFollow = await Factory.build('user', {
+            name: 'User I Follow',
+            about: 'I follow this user',
+            id: 'uifollow',
+          })
+
+          const userFollowingMe = await Factory.build('user', {
+            name: 'User Following Me',
+            about: 'This user follows me',
+            id: 'ufollowsme',
+          })
+          await user.relateTo(userIFollow, 'following')
+          await userFollowingMe.relateTo(user, 'following')
+        })
+
+        it('will be removed completely', async () => {
+          const relation = await database.neode.cypher(
+            'MATCH (user:User {id: $id})-[relationship:FOLLOWS]-(:User) RETURN relationship',
+            { id: (await user.toJson()).id },
+          )
+          const relations = relation.records.map((record) => record.get('relationship'))
+          expect(relations).toHaveLength(2)
+          await mutate({ mutation: deleteUserMutation, variables })
+          const relation2 = await database.neode.cypher(
+            'MATCH (user:User {id: $id})-[relationship:FOLLOWS]-(:User) RETURN relationship',
+            { id: (await user.toJson()).id },
+          )
+          const relations2 = relation2.records.map((record) => record.get('relationship'))
+          expect(relations2).toHaveLength(0)
+        })
+      })
     })
   })
 })

backend/src/graphql/resolvers/users.ts

@@ -280,6 +280,9 @@ export default {
               WITH user
               OPTIONAL MATCH (user)<-[:OWNED_BY]-(socialMedia:SocialMedia)
               DETACH DELETE socialMedia
+              WITH user
+              OPTIONAL MATCH (user)-[follow:FOLLOWS]-(:User)
+              DELETE follow
               RETURN user {.*}
             `,
           { userId },