[Regression Bug] Updated atom value not propagated to component

[xbaun]

I am using an atom (A) to control if an atom (B) should return the value of an atom (C) otherwise a default value is returned. See the example below: https://codesandbox.io/s/dark-http-bsili?file=/src/App.tsx

const aAtom = atom<any>(false);
aAtom.debugLabel = "aAtom";
aAtom.onMount = (set) => {
    console.log("onMount: aAtom");
    setTimeout(() => {
        set(true);
    }, 1000);
};

const cAtom = atom<any>(1);
cAtom.debugLabel = "cAtom";
cAtom.onMount = (set) => {
    console.log("onMount: cAtom");
    set(2);
};

const bAtom = atom<any>((get) => {
    const a = get(aAtom);
    console.log("a=", a);
    if (a) {
        return get(cAtom);
    }
    return 1;
});
bAtom.debugLabel = "bAtom";

The problem is, that the changed value of atom (C) is never propagated to the invoking component through useAtom. The error occurs when there is no externally triggered rendering within the calling component, which re-evaluates the useAtom hook. I think, there is somewhere a flushPending missing. I tried to figure out what could be a possible fix, but I did not found any good solution.

Affects version 1.5.0. Worked with 1.4.2 1.4.9.

---

BTW: I think the useEffect call at https://github.com/pmndrs/jotai/blob/main/src/core/useAtom.ts#L103-L105 should pass its dependencies. If so, a forced rendering has no effect anymore on the bug above.

  useEffect(() => {
    store[COMMIT_ATOM](atom, version)
  }, [store, atom, version]);

[dai-shi]

Thanks for reporting. I think we miss tests to cover this...

Affects version 1.5.0. Worked with 1.4.2.

This almost indicates, this is a bug. Note: it works with 1.4.9 too.

[xbaun]

I updated the version in the bug description.

[smashercosmo]

Hm... I think I also stumbled upon this bug, but for me the last working version is 1.4.6

[dai-shi]

Are you sure? That sounds like a different bug. Thanks for reporting anyway.
I'm currently working hard on issue.

[smashercosmo]

Yeah, maybe different bug, but same behaviour: updated atom value is not reflected in a component. Works in 1.4.6, doesn't work in all other versions > 1.4.6. I'll try to create reproduction sandbox.

[dai-shi]

Would you guys try if https://ci.codesandbox.io/status/pmndrs/jotai/pr/960/builds/208213 fixes issues? (See "Local Install Instructions")

[xbaun-mms]

Couldn't test it with my application because it breaks currently because of #967. But as far es I can see it, the test is working and increasing delays also works perfectly.

[dai-shi]

See https://ci.codesandbox.io/status/pmndrs/jotai/pr/960 for new builds.

[dai-shi]

doesn't fix

[dai-shi]

#960 should fix this.
Please try: https://ci.codesandbox.io/status/pmndrs/jotai/pr/960