Nor do I receive finalData. It does work all the time with

stream: false

. The other 50% of the time it works normally. Here is how I use it:

tsx
export function Component() {

  const getMyFunction = useGetMyFunction()

  console.log(getMyFunction)

  useEffect(() => {
    getMyFunction.mutate("input")
  }, [])
}

It re-renders a few times and fills my schema with null values, then nothing. Not even an error. The interesting part is that the server function logs the full results parsed from the LLM. I have logged

useBamlAction

and it gets stuck at this line

const { value, done } = await reader.read()

Any idea?

in dev mode useEffects sometimes will run twice. Can you try doing the mutate inside a button click temporarily and see if you get the same issue?

Indeed, it seems to work with a button but not even this seems to do the trick:

tsx
export function Component() {
  const [tick, setTick] = useState(0)
  const getMyFunction = useGetMyFunction()

  console.log(getMyFunction)

  useEffect(() => {
    if (tick === 0) {
      setTick((prev) => prev + 1)
    }
    if (tick === 1) {
      useGetMyFunction.mutate("input")
    }
  }, [tick])
}

the thing is that react will run the setTick potentially out of order

I'm going to take a look at what can be done in the hook. Its should be able to work that way

CC @greg (BAML) -- i think you just made a tiny nextjs app -- did you have this problem?

Thanks aronv. Tried to log mutate and the underlying

GetMyFunction

. The logs only appear a single time.

oh interesting. Yeah if there's any improvements we can make to the generated code we're glad to revisit this

Hi @Qwertas! I like the hypothesis that ~50% of your responses are getting dropped because of dev mode running the

useEffect

hook twice. I wonder if we can just verify that by adding a

console.log

right under the call to

mutate

in your original example? If we see that, then we can go down the path of hook-debugging (which would probably involve either turning StrictMode off or implementing a cleanup function, IIUC the docs I'm looking at).

Hello @greg (BAML) thanks for helping. When using in a button onClick, I did not had any issues, with streaming off too. I don't have React strict mode enabled except if it's on by default. Also I did log the mutate function and ran once (one log). I'm going to try that again as soon as I'm back home. To be sure the useEffect ran once, I did this:

export function Component() {
  const [tick, setTick] = useState(0)
  const getMyFunction = useGetMyFunction()

  console.log(getMyFunction)

  useEffect(() => {
    if (tick === 0) {
      setTick((prev) => prev + 1)
    }
    if (tick === 1) {
      useGetMyFunction.mutate("input")
    }
  }, [tick])
}

Which should only have the condition

if (tick === 1) {

met once right? Same issue and only one log. Also my useEffect run as soon as the app starts maybe could be an issue. Could you try with a useEffect at the start of you app and see if you get the same issue?

Yah, I will try to reproduce the issue, good idea.

By the way I have described my whole experiment here -> https://github.com/BoundaryML/baml/issues/2413

Ah fantastic!