Improve performance of set method

[ozcanovunc]

Hi,

In our system, we store additional keys in Redis and need to sync certain data within session storage. To achieve this, we require a callback that triggers whenever a session is saved to Redis, allowing us to perform operations on our custom keys.

Currently, as a workaround, we have overridden the set method of the Redis store:

const store = new RedisStore({ ... });

const originalSet = store.set;
store.set = async function (...args) {
  const session = args?.[1];

  // Custom logic

  return originalSet.apply(store, args);
};

However, this approach is fragile and requires validation each time a new version of connect-redis is released.

To make this process more robust and maintainable, we propose adding a built-in onSet callback to connect-redis. This would provide a cleaner, more reliable way to execute custom logic when a session is saved.

Let me know if you need refinements!
Thanks in advance 🚀

Above was the original request. Currently this PR aims to call the serializer.stringify when necessary.

[ozcanovunc]

@wavded 👀

[ozcanovunc]

@wavded 👀

[wavded]

@ozcanovunc Sorry I've been busy and I haven't had a chance to look in depth on this. I did have a few initial questions though. One, it seems like this is a general express session feature (firing an event when updating the session) would that be better served in the main express-session repo to include there? Two, are there no events on the Redis clients themselves to capture writes happening? Three, if we kept it in here, it may make sense to follow the event emitter pattern as we inherit it from the session Store instead of using one-off event functions.

[ozcanovunc]

Hi @wavded no worries, your comment got me thinking, I can achieve my goal using serializer parameter. I updated this PR to optimize the set method a little.

[wavded]

Fair enough, I will merge that in.