Nuxt•4w ago

Issue with Vue 3 + Nuxt 3 useFetch Data Not Displaying in Template

Background I’m building an app using Nuxt 3 and Vue 3 (Node v20.18.0). I’m running into a fundamental issue with template reactivity when trying to display data fetched with useFetch. Specifically: - I can log the data from useFetch in <script setup>, and the data is correct. - However, when binding to the fetched data in the template, the expected reactivity doesn’t occur. - Some solutions work (like wrapping the data in computed), but they feel unnecessary for something as fundamental as this. What I’ve Tried 1. Debugging Data Reactivity

console.log("Data:", data.value); 
console.log("Title:", data.value.title);

console.log("Data:", data.value); 
console.log("Title:", data.value.title);

- These logs always show the correct data and title values. 2. Providing Default Values

const { data } = await useFetch('/api', { default: () => ({ title: 'Untitled' }) });

const { data } = await useFetch('/api', { default: () => ({ title: 'Untitled' }) });

- Ensures data.value is initialized, but this doesn’t fix the template reactivity for data.value.title. 3. Optional Chaining in the Template

<p v-else>Title: {{ data?.value?.title || 'No title available' }}</p>

<p v-else>Title: {{ data?.value?.title || 'No title available' }}</p>

- Prevents errors but still doesn’t display the title, even though <pre>{{ data }}</pre> confirms it exists. 4. Using computed

const computedData = computed(() => data.value);

const computedData = computed(() => data.value);

- This works, and the title renders correctly when accessed as computedData.title. Questions 1. Why is template reactivity for data.value.title failing? - This seems like a fundamental part of Vue’s reactivity system, so I’m not sure why I need computed for it to work. 2. Is this an issue with Nuxt’s useFetch? - Could Nuxt be optimizing reactivity in a way that breaks expected behavior for deep properties? 3. Am I misusing useFetch? - Is there a better way to fetch data in Nuxt 3 to avoid this issue entirely? 4. Is this a known issue? - I couldn’t find documentation addressing this specific behavior. Should I file a bug report?

3 Replies

kapa.ai•4w ago

Hi @kāné. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave: ---------------------- Based on the knowledge sources provided, I can address some aspects of your question about the issue with Vue 3 + Nuxt 3 useFetch data not displaying in the template. However, it's important to note that the information available doesn't fully cover all the specifics of your situation. 1. Regarding why template reactivity for data.value.title is failing: The issue you're experiencing might be related to the shallow reactivity of the data object returned by useFetch. According to the Nuxt 3 upgrade guide (https://nuxt.com/docs/getting-started/upgrade#shallow-data-reactivity-in-useasyncdata-and-usefetch), the data object returned from useFetch is now a shallowRef rather than a ref. This means that while the entire data object is reactive, properties within it may not trigger reactivity when changed. 2. Regarding whether this is an issue with Nuxt's useFetch: This behavior is intentional and was introduced as a performance optimization. The upgrade guide (https://nuxt.com/docs/getting-started/upgrade#shallow-data-reactivity-in-useasyncdata-and-usefetch) states that this change brings a significant performance improvement for deeply nested objects and arrays. 3. About potentially misusing useFetch: Based on the provided information, it doesn't appear that you're misusing useFetch. However, if you need deep reactivity, you have a couple of options: a. You can opt-in to deep reactivity on a per-composable basis:

   const { data } = useFetch('/api/test', { deep: true })

   const { data } = useFetch('/api/test', { deep: true })

b. You can change the default behavior project-wide (though this is not recommended):

   // nuxt.config.ts
   export default defineNuxtConfig({
     experimental: {
       defaults: {
         useAsyncData: {
           deep: true
         }
       }
     }
   })

   // nuxt.config.ts
   export default defineNuxtConfig({
     experimental: {
       defaults: {
         useAsyncData: {
           deep: true
         }
       }
     }
   })

4. Regarding whether this is a known issue: This is not an issue per se, but rather an intentional change in behavior. It's documented in the Nuxt 3 upgrade guide (https://nuxt.com/docs/getting-started/upgrade#shallow-data-reactivity-in-useasyncdata-and-usefetch). As for your specific implementation, without seeing more of your code, it's difficult to pinpoint exactly why computed works while direct access doesn't. However, using computed is a valid approach to ensure reactivity when working with complex data structures. It's worth noting that the Nuxt documentation on data fetching (https://nuxt.com/docs/getting-started/data-fetching#the-need-for-usefetch-and-useasyncdata) explains that useFetch is designed to solve issues related to double data fetching and hydration. If you're still experiencing unexpected behavior, you might want to double-check your implementation against the examples in the documentation. If you continue to face issues after trying these approaches, you might want to create a minimal reproduction of your problem and consider reporting it to the Nuxt GitHub repository for further investigation. ---------------------- Note: you can ask me a follow up question by @ mentioning me again :speech_balloon: ----------------------

kapa.ai•4w ago

<@308827449213452289> Kapa.ai is still learning and improving, please let me know how I did by reacting below.

Cue•4w ago

When you use data.value in template, you will lose reactivity. Refs are unwrapped in template, so why not just use data.title etc?

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Issue with Vue 3 + Nuxt 3 useFetch Data Not Displaying in Template