Nuxt•3d ago

How-to set a response header in the server route

I'd like to know how to explicitly set a header in response to a server route. Specifically, I'd like to set the Content-Type of the returned data. This question specifically relates to /server routes. I understand it's possible to set the HTTP response status code using setResponseStatus(event, 202). However, I can't find any details on setting the response headers. For example, I have some code that generates a sitemap and returns this as a promise-wrapped buffer. Or some code that generates dynamic images and returns these also as a buffer...

export default defineEventHandler(async (event) => {
  // Build sitemap - e.g. using node-sitemap
  const sitemap = new SitemapStream({
    hostname: FRONTEND_URL,
    xmlns: {
      xhtml: true,
      image: true,
      video: true,
      custom: [
        'xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd"',
        'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"',
      ],
    }
  })

  // Fetch all documents
  const projects = await fetchProjects();
  const docsPages = await fetchDocsPages(projects);

  // Write pages
  writeHomepage(sitemap);
  writeProjects(projects, sitemap);
  writeDocs(projects, docsPages, sitemap);
  writeSpecialPages(sitemap);

  sitemap.end()

  return streamToPromise(sitemap);
})

export default defineEventHandler(async (event) => {
  // Build sitemap - e.g. using node-sitemap
  const sitemap = new SitemapStream({
    hostname: FRONTEND_URL,
    xmlns: {
      xhtml: true,
      image: true,
      video: true,
      custom: [
        'xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd"',
        'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"',
      ],
    }
  })

  // Fetch all documents
  const projects = await fetchProjects();
  const docsPages = await fetchDocsPages(projects);

  // Write pages
  writeHomepage(sitemap);
  writeProjects(projects, sitemap);
  writeDocs(projects, docsPages, sitemap);
  writeSpecialPages(sitemap);

  sitemap.end()

  return streamToPromise(sitemap);
})

This returns the buffered sitemap text! Great - but there's no content-type set, meaning the browser has to implicitly infer its type. That's fine, but in my use case, a website I supply sitemaps too via a hook neccessitates the content type being explicitly set in the response header. Similarly, another needs those images to have an implicitly-set content-type header to be displayed correctly.

2 Replies

kapa.ai•3d ago

Hi @Will. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave: ---------------------- To set a response header in a Nuxt server route, you can use the setResponseHeader utility function. This function allows you to explicitly set headers for your server route responses. Here's how you can modify your code to set the Content-Type header:

import { setResponseHeader } from 'h3'

export default defineEventHandler(async (event) => {
  // Set the Content-Type header for XML
  setResponseHeader(event, 'Content-Type', 'application/xml')

  // Your existing sitemap generation code...
  const sitemap = new SitemapStream({
    // ... sitemap configuration
  })

  // ... rest of your sitemap generation code

  return streamToPromise(sitemap)
})

import { setResponseHeader } from 'h3'

export default defineEventHandler(async (event) => {
  // Set the Content-Type header for XML
  setResponseHeader(event, 'Content-Type', 'application/xml')

  // Your existing sitemap generation code...
  const sitemap = new SitemapStream({
    // ... sitemap configuration
  })

  // ... rest of your sitemap generation code

  return streamToPromise(sitemap)
})

In this example, we're importing the setResponseHeader function from the 'h3' package, which is used internally by Nuxt. We then use this function to set the 'Content-Type' header to 'application/xml' for the sitemap response. For your image generation case, you would set the appropriate Content-Type for images, such as 'image/png' or 'image/jpeg', depending on the image format you're generating. This approach is documented in the H3 Utils Response documentation (https://h3.unjs.io/utils/response#setresponseheaderevent-name-value), which shows how to set response headers in Nuxt server routes. Remember that setResponseHeader should be called before returning the response data. This ensures that the header is set correctly for the outgoing response. If you need to set multiple headers, you can use the setResponseHeaders function instead:

import { setResponseHeaders } from 'h3'

export default defineEventHandler(async (event) => {
  setResponseHeaders(event, {
    'Content-Type': 'application/xml',
    'Cache-Control': 'max-age=600'
  })

  // ... rest of your code
})

import { setResponseHeaders } from 'h3'

export default defineEventHandler(async (event) => {
  setResponseHeaders(event, {
    'Content-Type': 'application/xml',
    'Cache-Control': 'max-age=600'
  })

  // ... rest of your code
})

This method is also documented in the H3 Utils Response documentation (https://h3.unjs.io/utils/response#setresponseheadersevent-headers). By using these utilities, you can ensure that your server routes return responses with the correct headers, meeting the requirements of the services consuming your sitemaps or images. ---------------------- Note: you can ask me a follow up question by @ mentioning me again :speech_balloon: ----------------------

kapa.ai•3d ago

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How-to set a response header in the server route