Slices patterns, access multiple slices: data cannot be accessed

[norama]

Summary

Using your multiple slices pattern, I tried to add a slice which acts on other slices, as in your docs:
https://docs.pmnd.rs/zustand/guides/slices-pattern#updating-multiple-stores
When I want to create a function acting on data in the slices then the default values are returned instead of the actual data.
Accessing the functions in the slices (as in your example) works fine, but how to access the data?
Also tried to add a get parameter when creating the slices according to
https://docs.pmnd.rs/zustand/recipes/recipes#read-from-state-in-actions
but this did not work for slices, they do not seem to get the get parameter.

Link to reproduction

https://codesandbox.io/s/silly-tamas-2rp6gx?file=/src/store/index.ts

Reset works, but Calc sum always displays 0.

Check List

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• [ x] I've already opened a discussion before opening this issue, or already discussed in other media.

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• [ x] I've added a link to a typescript playground or codesandbox with a minimal reproduction.

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• [ x] I've read the typescript guide, in particular that create is to be used as create<T>()(...) and not create<T>(...).

[dai-shi]

Can anyone help here?

[dbritto-dev]

@dai-shi I can help

[dbritto-dev]

@norama you are trying to create actions base on create slice functions which is wrong, that's why you always get the default values. You should always use get() to access to any function or prop/field.

Here you go

const createResetAllSlice = (set, get) => ({
  resetAll: () => {
    get().resetApples();
    get().resetPears();
  },
  sum: () => get().apples + get().pears
});

[norama]

@dbritto-dev Thanks a lot for the solution and the quick reaction!

It was also strange for me that we create new slices in order to access fields
(I also wonder why this works for functions at all), but this is what your docs says:
https://docs.pmnd.rs/zustand/guides/slices-pattern#updating-multiple-stores
So please correct the docs!
Also please include typescript docs for this because it is far from trivial as this slice has access to the whole store.

Now I realize that you have it elsewhere in the docs in a different way:
https://docs.pmnd.rs/zustand/guides/slices-pattern#slicing-the-store-into-smaller-stores

export const createBearSlice = (set) => ({
  bears: 0,
  addBear: () => set((state) => ({ bears: state.bears + 1 })),
  eatFish: () => set((state) => ({ fishes: state.fishes - 1 })),
})

Here this slice directly refers to state.fishes which is in another slice.
I thought it is a bug in the docs but the state will be merged and the slice refers to the merged state.
Anyway, it would be nice if you could describe this in more detail in the docs.

[dbritto-dev]

@norama you could access state using get() or inside of set() callback fn

[dbritto-dev]

@norama about multiple stores you are right, the docs could misguide you I'll work on that but apart from that since we are talking about slices (same store/state) you can access to whatever field from the store/state. Just keep in mind talking about slices doesn't mean different stores just different fields in the same stores kind of namespace but that's it. So is not like you couldn't access other slice from a different slice.

[dbritto-dev]

@norama here you go -> #2046

[norama]

Thank you for the quick docs update, just some typescript example please.