Nuxt•4mo ago

moving from Nuxt2 useFetch to Nuxt3 useAsyncData - how would you refactor this example?

Hello, as a title says, how would you refactor this example to keep SSR working exactly 1:1? Nuxt 2

  const homePage = ref<HomePage | null>(null)
  const homePageLoaded = ref<boolean>(false)

  useFetch(async () => {
    homePage.value = await loadHomePage()
    homePageLoaded.value = true
  })

  const homePage = ref<HomePage | null>(null)
  const homePageLoaded = ref<boolean>(false)

  useFetch(async () => {
    homePage.value = await loadHomePage()
    homePageLoaded.value = true
  })

24 Replies

JV•4mo ago

I tried to refactor it this way:

  const homePageLoaded = ref<boolean>(false)

  const { data: homePage } = useAsyncData(async () => {
    homePage.value = await loadHomePage()
    homePageLoaded.value = true

    return homePage
  })

  const homePageLoaded = ref<boolean>(false)

  const { data: homePage } = useAsyncData(async () => {
    homePage.value = await loadHomePage()
    homePageLoaded.value = true

    return homePage
  })

But the homePageLoaded is not synced properly and I dont think using useState for this is a good way... could you please help/explain, how to refactor it with the smallest amount of other code changes possible?

Wild•4mo ago

Not a expert, but I think something like this should work

  const { data: homePage, pending: homePageLoaded  } = useAsyncData(async () => {
    return await loadHomePage()
  })

  const { data: homePage, pending: homePageLoaded  } = useAsyncData(async () => {
    return await loadHomePage()
  })

JV•4mo ago

Do not rely on variable name or usage, the main issue is how to modify other refs inside useAsyncData

Wild•4mo ago

I am not to sure about your goal, but maybe take a look at the onReponse param ?

const { data, pending, error, refresh } = await useFetch('/api/auth/login', {
  onRequest({ request, options }) {
    // Set the request headers
    options.headers = options.headers || {}
    options.headers.authorization = '...'
  },
  onRequestError({ request, options, error }) {
    // Handle the request errors
  },
  onResponse({ request, response, options }) {
    // Process the response data
    localStorage.setItem('token', response._data.token)
  },
  onResponseError({ request, response, options }) {
    // Handle the response errors
  }
})

const { data, pending, error, refresh } = await useFetch('/api/auth/login', {
  onRequest({ request, options }) {
    // Set the request headers
    options.headers = options.headers || {}
    options.headers.authorization = '...'
  },
  onRequestError({ request, options, error }) {
    // Handle the request errors
  },
  onResponse({ request, response, options }) {
    // Process the response data
    localStorage.setItem('token', response._data.token)
  },
  onResponseError({ request, response, options }) {
    // Handle the response errors
  }
})

otherwise myvar.value seems like the way

BeerDuck•4mo ago

@JV Do you mean your homePageLoaded.value is at the end still false?

Wild•4mo ago

also note the await before the UseFetch

JV•4mo ago

@BeerDuck exactly!

manniL•4mo ago

why not const { data, status } = await useFetch() and check if status is PENDING? ah, saw this ideally you don't a watcher based on data (or status or similar) would be better

BeerDuck•4mo ago

I try to explain what happens, and maybe it is not 100% correct but. Your code within your asyncdata will not be executed a second time. because the whole function gets skipped, and the data: homepage gets filled in without executing the function again. This is why everything that happens within the function does not get executed a second time. What i think you just want is an normal function around it.

const homePageLoaded = ref(false);
const homePage = ref(1);
async function loaddata(){
   const{ data: thedata } = useAsyncData( async () => {
    return  await loadHomePage();
  });
  homePage.value=thedata;
  homePageLoaded.value = true;
}
await loaddata();

btw above code isnt optimal or directly logical to use in any situation in my mind, but i think this solves your issue. And looks mostly like your old code

JV•4mo ago

Ok, and one more question - does useAsyncData have some way how to add event listeners like onRequest like you showed in your example with useFetch? @Wild

BeerDuck•4mo ago

watch(() => watachablevalue, (newVal,oldVal) => {
    //use variable or do something when variable changes. 
});

This keeps track on variable changes if i am correct.

Wild•4mo ago

useFetch being a shorthand for useAsyncData, it should accept exactly the same parameters, although I can't confirm this will 100% work it should

JV•4mo ago

@manniL / TheAlexLichter sorry for mention, but only you could propably know if this could be a problematic usage? I know its not ideal usage, but its acrually working - can this lead to some unexpected behavior, or it is safe to use? I have some purposes why I need to use it somehow like this (rewritting old nuxt2 project into nuxt3 with as little changes as possible accross whole project)

manniL•4mo ago

no, useAsyncData in useAsyncData is not okay It'd help explain "some purposes" 🙂

JV•4mo ago

@manniL / TheAlexLichter thank you for your answer! Ill try to explain "some purposes" we are using "useFetch" with our wrapper, which provides some events like "onSuccess", "onError" etc. In some cases, we need to modify data that comes from api call - this maybe could be achieved by computed properties. But I would like to keep our wrapper with "onSuccess", "onError" events

manniL•4mo ago

"we need to modify data" -> how about using transform? or doing that in asyncData after the fetching the call from an API?

JV•4mo ago

I maybe overengineered that, now it looks clear, Ill try to do my best and in case of any other problems Ill let you know - if I can. Thank you so much!

manniL•4mo ago

no problem 👍

JV•4mo ago

@manniL / TheAlexLichter how would you implement these functions like "onSuccess"/"onError"? We are using "ste-simple-events" package for that

manniL•4mo ago

Hard to tell without a bit more code. but probably in your $fetch (as it has interceptor support)

JV•4mo ago

Im now working with this in mind - trying to create composable which allows me to fetch data of HomePage on SSR and on client either, when I come from another subpage. This is just example in my mind, but I dont think this will be ok too.. @manniL / TheAlexLichter - this immediate: false and calling execute is important for me - Im executing it from another composable

export const useHomePage = async () => {
  
  const onSuccess = new SimpleEventDispatcher()
  const onError = new SimpleEventDispatcher()
  
  const {data, execute} = useAsyncData(async () => {
    try {
      const response = await doSomething()
      onSuccess.dispatch(response)
      return response
    } catch (e) {
      onError.dispatch(e)
    }
  }, {immediate: false})

  await execute()

  return {
    onSuccess,
    onError,
    data,
    execute
  }
}

export const useHomePage = async () => {
  
  const onSuccess = new SimpleEventDispatcher()
  const onError = new SimpleEventDispatcher()
  
  const {data, execute} = useAsyncData(async () => {
    try {
      const response = await doSomething()
      onSuccess.dispatch(response)
      return response
    } catch (e) {
      onError.dispatch(e)
    }
  }, {immediate: false})

  await execute()

  return {
    onSuccess,
    onError,
    data,
    execute
  }
}

manniL•4mo ago

good point! besides that: execute and immediate false is a bit strange. You could just do a refresh which comes from the useAsyncData and return the whole composable "response object" instead

JV•4mo ago

isnt execute and refresh the same functionallity?

manniL•4mo ago

yes

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moving from Nuxt2 useFetch to Nuxt3 useAsyncData - how would you refactor this example?