subscribeKey will re-fire multiple times despite the value not changing

[ericschmar]

Finally found the issue in my app, and it turns out that the subscribeKey utility was firing upwards of 6-7 times when the value changed.

To keep it simple, I have a state object with many properties, one of which is a controlValue used for handling Tabs from Mantine. It's a simple string, and is changed whenever a user clicks on a different tab.

I had setup subscribeKey as follows:

subscribeKey(state, 'controlValue', (v) => {
    state.count = 0; // reset state value
    callApi();
}

function callApi() {
    startTransition(async () => {
         const result = api.get();
         state.items = [...result];
    })
}

I noticed after installing the redux dev tools that the first tab (the default tab) would correctly call my api. Then on tab switch, the subscribeKey function would fire upwards of 6-7 times resulting in various components on the screen re-rendering and in the process making interacting with them impossible.

I'm not sure the reason this happens as it's a simple string that is triggering these changes, not a complex object. It seems like whatever is checking to see if the value changed is the best place to start looking.

Additionally, this brings up a question of: Would it be valuable to add a config object to subscribing that allows for deduplication and throttling? It's a common usecase to use subscribing to an effect to trigger other things, and ensuring that things run once or don't get spammed would be important.

[dai-shi]

Is it possible to reproduce the behavior without tab switch? I would like see the minimal setup.

That said, I'm not sure if there's anything to do in Valtio core.

It's a common usecase to use subscribing to an effect to trigger other things

Yeah, if that's the common case, I think developing a new third-party library would make sense. subscribe isn't designed for "effects". It's to notify any changes that proxy captures.
We have a new org https://github.com/valtiojs. Contributions are welcome.