Sanity CDN image links from WYSIWYG not working

Glad to hear your blog is working nicely! This is a common issue when working with images in Portable Text. The problem is that Sanity stores image references as asset objects, not ready-to-use URLs. You need to transform these references into proper CDN URLs using @sanity/image-url.

Here's what's happening: when you add an image in the Portable Text editor (WYSIWYG), Sanity stores it as a reference object with an _type of image and an asset reference. But to actually display it, you need to process that reference through Sanity's image URL builder to get a working cdn.sanity.io URL.

The solution is to create a custom serializer for image blocks in your Portable Text renderer using @portabletext/react:

import { PortableText } from '@portabletext/react'
import imageUrlBuilder from '@sanity/image-url'
import { client } from './sanityClient' // your Sanity client

// Set up the image URL builder
const builder = imageUrlBuilder(client)

function urlFor(source) {
  return builder.image(source)
}

// Custom serializers for Portable Text
const components = {
  types: {
    image: ({value}) => {
      if (!value?.asset?._ref) {
        return null
      }
      return (
        <img
          src={urlFor(value).width(800).url()}
          alt={value.alt || ' '}
          loading="lazy"
        />
      )
    }
  }
}

// Use it in your component
function BlogPost({ content }) {
  return <PortableText value={content} components={components} />
}

Key steps:

1. Install @sanity/image-url if you haven't: npm install @sanity/image-url
2. Create an image URL builder instance with your Sanity client
3. Add a custom serializer for the image type in your Portable Text components
4. Use the builder to transform the asset reference into a working cdn.sanity.io URL

You can also add image transformations like .width(), .height(), .fit(), .quality(), or even .auto('format') for automatic WebP/AVIF format selection to optimize the images for your needs.

If your images are structured differently (like custom image blocks), you might need to adjust the value.asset._ref path to match your schema. The important part is passing the image reference through the URL builder before rendering it.