Postgres SET runtime variables with TypeORM, how to persist variable during the life of the connection between calls - postgresql

Question

I have NodeJS web server using GraphQL using 2 connections. One has admin access, the other crud access.
Underlying Postgres DB has a Row Level Security policy, i.e.:
ALTER TABLE main.user ENABLE ROW LEVEL SECURITY;
CREATE POLICY user_isolation_policy ON main.user USING (id = current_setting('app.current_user_id')::UUID);
Before I login a user, I need to get their id from the db, then set the current_user_id variable in Postgres session while logging in.
However, when I try to fetch users back, I am expecting to get back only the logged in user, not everyone - this is how it behaves using pgAdmin. However, here I am getting the following error:
error: error: unrecognized configuration parameter "app.current_user_id"
Here is how I log a user in:
#Resolver()
export class LoginResolver {
#Mutation(() => LoginResponse)
public async login(
#Arg('email') email: string,
#Arg('password') password: string,
#Ctx() { res }: AppContext
): Promise<LoginResponse> {
try {
// get user from the admin repo so we can get their ID
const userRepository = (await adminConnection).getRepository(User)
const user = await userRepository.findOne({ where: { email } })
if (!user) throw new Error('user not found')
// using the api repo (not admin), set the variable
User.getRepository().query(`SET app.current_user_id TO "${user.id}"`)
const isValid = await bcrypt.compare(password, user.password)
if (!isValid) throw new Error('incorrect password')
if (!user.isConfirmed) throw new Error('email not confirmed')
sendRefreshToken(res, user.createRefreshToken())
return { token: user.createAccessToken() }
} catch (error) {
throw new Error(error)
}
}
}
Here is how I try to fetch back users:
#Resolver()
export class UsersResolver {
#Authorized(UserRole.admin, UserRole.super)
#Query(() => [User])
public users(): Promise<User[]> {
return User.find()
}
}
Please note that, if I remove the policy, GraphQL runs normally without errors.
The set variable is not persisting. How do I persist the variable while the user is logged in?

Answer 1

This approach works for me:
import { EntityManager, getConnection, getConnectionManager, getManager } from "typeorm";
import { EventSubscriber, EntitySubscriberInterface, InsertEvent, UpdateEvent, RemoveEvent } from "typeorm";
#EventSubscriber()
export class CurrentUserSubscriber implements EntitySubscriberInterface {
// get the userId from the current http request/headers/wherever you store it (currently I'm typeorm only, not as part of nest/express app)
async setUserId(mng: EntityManager, userId: string) {
await mng.query(`SELECT set_config('app.current_user_id', '${userId}', true);`)
}
async beforeInsert(event: InsertEvent<any>) {
await this.setUserId(event.manager, 'myUserId');
}
async beforeUpdate(event: UpdateEvent<any>) {
await this.setUserId(event.manager, 'myUserId');
}
async beforeRemove(event: RemoveEvent<any>) {
await this.setUserId(event.manager, 'myUserId');
}
}
Don't forget to configure the subscribers property in ormconfig.js, e.g. :
"subscribers": [
"src/subscribers/CurrentUserSubscriber.ts",
],