How to type snapshots?

[skokenes]

Hi, I am using valtio with TypeScript. I set up a proxy state with some nested type, like

const state = proxy<{ a: TypeA }>({ a: {} });

When I consume the state as a snapshot using useSnapshot in my components, I want to pass snapshot.a to functions that are expecting the type TypeA. However, I am getting TS errors because snapshot.a is now typed as a readonly variant of my TypeA.

Is there some sort of utility type I can use to resolve this issue? I tried modifying my functions to expect a type like ReadOnly<TypeA>, but that still did not match snapshot.a's type.

[dai-shi]

A snapshot is readonly, and if you want to loosen (lie) the type, please assert it.

const snap = useSnapshot(state) as typeof state

This was controversial. Please see #327 for more context.

[lmaero]

Hi @dai-shi , thanks for this amazing state management library.

Is this still considered the best way or can you expose the Snapshot as a type?

[dai-shi]

Yes, we will expose it in v2. Please try v2-beta #810 (#856). npm install valtio@next

But, as typeof state is still considered the best way if you want to loosen the type.

[lmaero]

Just did the change, it feels more intuitive to type things as Snapshot; excellent, thank you.

By any chance do you have any docs about -beta version? Just discovered this library, learning a lot!

[dai-shi]

We have a small migration guide in the v5 branch.