SolidJS•8mo ago

Await a resource inside a function?

This there a function which achieves something similar as my fictional "waitForResource" function here? Or should I refactor my code?

const myResource = createResource(...)

const handleSubmit = async () => {
  const data = myResource(); // T | undefined

  const data = await waitForResource(myResource()); // T
}

return (
  <form onSubmit={handleSubmit}>...

const myResource = createResource(...)

const handleSubmit = async () => {
  const data = myResource(); // T | undefined

  const data = await waitForResource(myResource()); // T
}

return (
  <form onSubmit={handleSubmit}>...

29 Replies

deluksic•8mo ago

If you do this under a transition, you can await an empty startTransition() call. It resolves when all resources resolve. I did not test this.

bigmistqke•8mo ago

What is the usecase? Conditional rendering you could do w <Show/> or <Suspense/>.

smushballOP•8mo ago

Unsure how to use the startTranstition in this case. I need to use from data from my resource inside a submit callback. Specifically, it's like an "Add to cart" function, which needs to check some logic based on your cart, and a resource which fetches from some external API

bigmistqke•8mo ago

I think this is what you are looking for

return (
 <Show when={myResource()} keyed>
  {
   (data) => ...
  }
 </Show>
)

return (
 <Show when={myResource()} keyed>
  {
   (data) => ...
  }
 </Show>
)

data in this case will be T without keyed data will be Accessor<T>

smushballOP•8mo ago

You would then pass data to the handleSubmit function?

bigmistqke•8mo ago

yes exactly onSubmit={e => handleSubmit(e, data)} or something

smushballOP•8mo ago

Aight Ty

bigmistqke•8mo ago

ur welcome!

deluksic•8mo ago

Thing is that the user now must wait for the resource to finish loading before clicking the button. Slightly different feel depending on how long that resource takes. Could be just fine if <1s

bigmistqke•8mo ago

Sure. But that was the behaviour of the original snippet, right? And sometimes that's exactly what we want. Just like Suspense, u can decide where u draw the boundary of what is and isn't rendered.

deluksic•8mo ago

Original snippet rendered regardless of the resource being ready I believe. But if it solves the problem for OP, this is much simpler and preferred way, for sure!

bigmistqke•8mo ago

ooo ur right i misread the code my bad

smushballOP•8mo ago

I would rather have an await resource() function, but sending the data from a Show callback is fine. It's more of a TypeScript issue

deluksic•8mo ago

Ill see if I can make a startTransition work in playground, but only much later today

smushballOP•8mo ago

Would be awesome if it were possible 😄

bigmistqke•8mo ago

I played around a bit with the idea for a waitForResource: https://playground.solidjs.com/anonymous/f767499f-81c2-4c81-8f02-36e1f2b25177

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smushballOP•8mo ago

Yup, that seems to do it

bigmistqke•8mo ago

tweaked it a little bit: https://playground.solidjs.com/anonymous/1ec29bf5-a0e8-4e07-a925-38e3915ab6fd the previous version wouldn't resolve if the promise returned a falsey value.

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bigmistqke•8mo ago

but ye i think u can get the main idea

smushballOP•8mo ago

Yup. I was just refactoring into the same ish thing Would be nice if Solid had a resource.promise() which resolved into the resource, but this function works well 😄

bigmistqke•8mo ago

I agree. Kind of surprised nobody made a suggestion for it on https://discord.com/channels/722131463138705510/1085604933849595924 yet

bigmistqke•8mo ago

Beauty of solid is that u can always make ur own wrapper if u really want that behavior https://playground.solidjs.com/anonymous/b4501633-864d-4de9-9f4e-562bab461e18 But now I made it I can see where this strategy fails, whereas regular resource doesn't: What if the fetcher is called again before the previous promise has been resolved? You are then awaiting an out-of-sync promise and end up with incorrect data. <Show/> and that waitForResource-helper would just wait for the second promise is resolved.

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smushballOP•8mo ago

I think that depends on how Solid createResource works? Does it cancel the running promise when calling refetch ?

bigmistqke•8mo ago

this visualises a bit what i was talking about

bigmistqke•8mo ago

left the waitForResource, right with .promise

smushballOP•8mo ago

Makes sense

cirilla•8mo ago

this maybe?

resource.promise = async () => {
    while (true) {
      const p = promise;
      try {
        const result = await promise;
        if (p !== promise) continue;
        return result
      } catch (error) {
        if (p !== promise) continue;
        throw error;
      }
    }
  };

resource.promise = async () => {
    while (true) {
      const p = promise;
      try {
        const result = await promise;
        if (p !== promise) continue;
        return result
      } catch (error) {
        if (p !== promise) continue;
        throw error;
      }
    }
  };

bigmistqke•8mo ago

nice

peerreynders•8mo ago

I'd say that the use case for a waitForResource is ultimately a misguided extension of the sequential illusion confusion prevalent in async JS development; i.e. an async click handler is a red flag to begin with. Also SolidJS manifests simple is better than easy and waitForResource smacks of convenience over correctness. Fundamentally createResource and it's 2.0 replacement createAsync are gateways from the async world into the sync reactive world- a transfer point from async events to synchronous reactive state. So once you are on the left side of a resource (or createAsync) you should be using reactive idioms. If you wish to exit from the reactive graph back into the async world then do so via an effect. - The button could be clicked before the resource is ready. Let's say the UX is better if the button can be clicked before the resource is ready because the convenient solution would be to simply disable the button until the resource is ready. - There is nothing in the OP that prevents the button from being spammed, effectively launching multiple, concurrent submissions; the handler being async suggest the sequence of operations is relevant so at the very least the button should be disabled once it has been clicked, and only re-enabled once the sequence of operations has completed. In other scenarios it may be necessary to queue each submission click with any data that should captured at the time of the click while other data is only added when it finally has its turn executing its sequence of operations. So my solution looks quite a bit different: https://playground.solidjs.com/anonymous/a6712ce2-5661-482c-b994-9b698f1aa537

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Await a resource inside a function?