Update the datasource/database read preference at the run time.

Describe the bug

For architectural reasons, I need to update the readPreference for a given method, on a given repository at the fly.
Please note, this change should be done at real time, and impact only this function invocation. However, the readPreferrence at the application level/datasource level should remain intact to "primaryPreferred".

For example,

this.userRepo.find(filter, { readPreference: "secondary" }); // request is still going to primary MongoDB server!
this.userRepo.findById(filter, { readPreference: "primary" });

I've tried this, but upon checking mongodb logs, this does not seem to work. All the request are going to primary server.

MongoDB version: v4.2

Logs

NA

Additional information

NA

Reproduction

https://github.com/shivambmgupta/loopback-next/tree/bug/read-preference-update

Inizia con il branch di riproduzione collegato e traccia le chiamate al repository usando find e findById con opzioni readPreference per invocazione su MongoDB 4.2. Verifica che una preferenza a livello di metodo modifichi solo quell’invocazione, mentre l’impostazione dell’applicazione e del datasource rimanga primaryPreferred; conferma la selezione del server risultante nei log di MongoDB.