How to access the response headers with Nuxt 3's useFetch?

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05-10-2024

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Unlocking the Secrets: Accessing Response Headers with Nuxt 3's useFetch

Nuxt 3's useFetch composable is a powerful tool for making API requests within your Vue.js application. But sometimes, you need more than just the response data. You might need to check the status code, parse the content type, or analyze the server's response headers. This is where understanding how to access those headers becomes essential.

The Scenario: A Need for Header Insight

Let's imagine you're building a blog application using Nuxt 3. Your API endpoint returns a JSON object of blog posts, but it also includes headers like Last-Modified to indicate when the data was last updated. You want to display this information to users.

Here's a simplified example of how you might use useFetch to retrieve blog posts:

// pages/blog.vue
<template>
  <div>
    <ul>
      <li v-for="post in posts" :key="post.id">
        {{ post.title }} (Last Modified: {{ lastModified }})
      </li>
    </ul>
  </div>
</template>

<script setup>
const { data: posts, pending, error } = await useFetch('/api/posts');

// You need to access the headers here to display the last modified date
let lastModified = null;
</script>

Unveiling the Headers: The useFetch Magic

useFetch provides a convenient way to access the response headers. The key lies in the returned object's response property. It contains valuable information, including:

• headers: An object containing all the response headers.
• status: The HTTP status code of the response.
• statusText: The textual description of the status code.
• redirected: Indicates whether the request was redirected.

Here's how you can access the Last-Modified header from our blog example:

// pages/blog.vue
<template>
  <div>
    <ul>
      <li v-for="post in posts" :key="post.id">
        {{ post.title }} (Last Modified: {{ lastModified }})
      </li>
    </ul>
  </div>
</template>

<script setup>
const { data: posts, pending, error, response } = await useFetch('/api/posts');

// Access the Last-Modified header
const lastModified = response.headers['last-modified']; 
</script>

Now, you can display the Last-Modified date directly in your blog post listings.

Beyond the Basics: Exploring Header Possibilities

This simple example demonstrates the power of accessing response headers. Here are a few other scenarios where this knowledge comes in handy:

• Content Negotiation: You can use the Content-Type header to dynamically adjust how your application renders data based on the user's preferred format (e.g., JSON, XML).
• Caching: The Cache-Control header can be used to set caching policies for your API responses, improving performance and reducing server load.
• Error Handling: Analyzing status codes and error-related headers can help you provide informative error messages to users.

Key Takeaways:

• useFetch in Nuxt 3 offers a straightforward way to access response headers.
• The response object provides valuable information about the API call, including status codes, headers, and redirection details.
• Understanding response headers unlocks advanced features like content negotiation, caching, and error handling.

Remember to refer to the official Nuxt 3 documentation for more details on useFetch and its features: https://v3.nuxtjs.org/api/composables/useFetch