Are async computed values possible?

[sitharus]

I've been looking at this problem for a while and I suspect I've got the wrong approach, hopefully someone can point me in the right direction.

I have a form that has a list driven from an API based on the value selected in another part of the form. Like a country/state selector, but the second list can't be created statically.

This looks like it's best solved with a computed that observes the first item's value, but a computed can't wait on an async computation, and there's nothing in mobx-utils that seems to match. This makes me think I'm approaching the problem wrong.

[danielkcz]

Can you maybe set up a small example with eg. CodeSandbox? I know what you mean, but technically async = Promise. I am not sure though if you return a new Promise from computed every time if it's possible to properly react to its changes. Maybe it would need to utilize observable.box to wrap that Promise ... but that's getting ugly.

I suppose, if this would be possible, we would not need to have such a complex approach for async actions. So my bets are it's not possible.

[jeremy-coleman]

https://github.com/danielearwicker/computed-async-mobx

[sitharus]

That doesn't work on MobX 6, though I guess I can adapt the concept...

[sitharus]

I can make an observable from a promise, so I guess a computed that returns an observable could work. I'll have a play.