Tips for avoiding template errors when retrieving data using Nuxt's fetch() method

Question

Tips for avoiding template errors when retrieving data using Nuxt's fetch() method

After transitioning my vue app to a nuxt app, I encountered an issue with vue-slick-corousel. In the original vue app, everything worked smoothly with vue-slick-carousel, but after making the necessary modifications for nuxt, the carousel wouldn't display properly on refresh. Oddly enough, if I edited the template in real time or navigated within the app without refreshing the page, the carousel worked perfectly upon revisiting the page(s). This is how I integrated vue-slick-corousel into my nuxt app:

//nuxt.config.js
plugins: [
  { src: './plugins/vue-slick-carousel.js' }
],

Here is the code from the plugin js file:

//vue-slick-carousel.js
import Vue from 'vue'
import VueSlickCarousel from 'vue-slick-carousel'

Vue.component('VueSlickCarousel', VueSlickCarousel)

And here's how it was implemented in the template:

<!-- CustomComponent.vue -->
<template>
  <div>
    <VueSlickCarousel :arrows="true" :dots="true">
      <div v-for="(cat, index) in categories" 
        :key="index"
        style="height: 20px; width: 10px; background-color: red; color: white"
      >
        {{cat.name}}
      </div>
    </VueSlickCarousel>
  </div>
</template>

<script>
  import VueSlickCarousel from 'vue-slick-carousel'
  import 'vue-slick-carousel/dist/vue-slick-carousel.css'
  // optional style for arrows & dots
  import 'vue-slick-carousel/dist/vue-slick-carousel-theme.css'
  export default {

    name: 'CustomComponent',
    data() {
      return {
        categories: []
      }
    },
    async fetch() {
      this.categories = await fetch(
        'https://*****************************/categories?limit=20'
      ).then(res => res.json())
    },
    components: {
      VueSlickCarousel
    },
  }
</script>

Upon refreshing the page, I encountered the error "TypeError: Cannot read property 'length' of undefined". However, the error disappeared when rendering the page again from the client side. I attempted enclosing the container under <client-only> and using conditions like v-if="slik.length", but none of these solutions worked. How can I resolve this issue?

javascript vue.js nuxt.js

Answer 1

Answer №1

UPDATE: I wanted to provide some insight on how the $fetchState.pending helper is used.

fetch() is a non-blocking function that allows data fetching when a page/component loads.
- asyncData() is blocking but only triggers during navigations, not on initial render, which can be frustrating.
- You can have a blocking navigation using a combination of fetch() and a middleware.
- Utilizing skeleton screens gives users a loading experience while making them feel like the app is actively loading (similar to Facebook).
Your template is synchronous and expects data to be immediately available. For instance, VueSlickCarousel waits for an array of items. Initially, you only have categories: [] in your setup via data().
$fetchState.pending is a useful indicator that shows when all API calls within fetch() are complete. If you're calling 4 APIs, it will be false only when all 4 calls finish.
- You also have the option to set it manually with this.$fetchState.pending = true, although this should be done carefully after understanding its implications.
By including
```
<VueSlickCarousel v-if="!$fetchState.pending">
```
, you essentially delay mounting the component until all fetch activities are completed. This prevents issues related to using methods like .length before the component is fully ready.

Here's a simplified Nuxt lifecycle diagram highlighting the importance of the fetch() hook. https://i.sstatic.net/bwNlf.png

Avoid combining async/await and then; stick to one approach (I recommend async/await).

async fetch() {
  const response = await fetch(
    'https://*****************************/categories?limit=20'
  )
  const fetchedCategories = await response.json()
  console.log('categories', fetchedCategories)
  this.categories = fetchedCategories
},

Additionally, using :key="index" in a v-for loop is considered bad practice since index is mutable. It's better to use a UUID from the API instead.

The following statements may not be necessary:

import VueSlickCarousel from 'vue-slick-carousel'

```
components: { VueSlickCarousel },
```

Answer 2

UPDATE: I wanted to provide some insight on how the $fetchState.pending helper is used.

fetch() is a non-blocking function that allows data fetching when a page/component loads.
- asyncData() is blocking but only triggers during navigations, not on initial render, which can be frustrating.
- You can have a blocking navigation using a combination of fetch() and a middleware.
- Utilizing skeleton screens gives users a loading experience while making them feel like the app is actively loading (similar to Facebook).
Your template is synchronous and expects data to be immediately available. For instance, VueSlickCarousel waits for an array of items. Initially, you only have categories: [] in your setup via data().
$fetchState.pending is a useful indicator that shows when all API calls within fetch() are complete. If you're calling 4 APIs, it will be false only when all 4 calls finish.
- You also have the option to set it manually with this.$fetchState.pending = true, although this should be done carefully after understanding its implications.
By including
```
<VueSlickCarousel v-if="!$fetchState.pending">
```
, you essentially delay mounting the component until all fetch activities are completed. This prevents issues related to using methods like .length before the component is fully ready.

Here's a simplified Nuxt lifecycle diagram highlighting the importance of the fetch() hook. https://i.sstatic.net/bwNlf.png

Avoid combining async/await and then; stick to one approach (I recommend async/await).

async fetch() {
  const response = await fetch(
    'https://*****************************/categories?limit=20'
  )
  const fetchedCategories = await response.json()
  console.log('categories', fetchedCategories)
  this.categories = fetchedCategories
},

Additionally, using :key="index" in a v-for loop is considered bad practice since index is mutable. It's better to use a UUID from the API instead.

The following statements may not be necessary:

import VueSlickCarousel from 'vue-slick-carousel'

```
components: { VueSlickCarousel },
```

Tips for avoiding template errors when retrieving data using Nuxt's fetch() method

Answer №1

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