PCE: $on applied to an extended client is also bound to the parent client

[millsp]

Originally posted by @realSergiy in #16500 (comment)

Hi,
I am using extended client, so that I could capture request id for every api call:

const extended = prismaClient.$extends({});
extended.$on('query', (e) => {
  log.debug('prisma_query', e);      
});

in the above snippet log would have all the request-specific information captured.
This works but it seems event subscriptions still happen on the original client and not the extended one. Therefore piling up subscriptions and logs with every request.

I was hoping to workaround with $use middleware, however it's not exposed on extended clients.

Any help on how to setup custom per request prisma logs (in nodejs server context) would be highly appreciated.

[SevInf]

From the discussions: we agreed that the way forwaard for GA is to disallow $on on extended client (similar to how we do it for middlewares and $use) thus requiring all event handlers to be added before any extensions.

For future, we'd like to introduce non-destructive extension component that would allow you to subscribe to query events for local fork. Sketch:

const xprisma = prisma.$extends({
   logging: {
       query: () => {}
   }
})