Migrating the Netlify Blog from Hugo to Eleventy using Sanity

Written by Sam Tancharoensuksavai

Over the last year, Netlify has been migrating our codebase from Hugo to Eleventy to streamline our development process and reduce client-side JavaScript. One of the last steps left was to migrate more than 700 markdown files, each representing a blog post, over to our internal Sanity instance. Luckily Sanity’s markdown-to-sanity tool made this process simple.

In this post, I’ll cover:

• using the markdown-to-sanity tool
• importing the .ndjson that's generated to our Sanity dataset
• how we're using Eleventy to render our blog posts
• any small gotchas I came across

Using markdown-to-sanity

Sanity offers a concise CLI tool to help with the importing and exporting of datasets. The CLI tool requires that the file be a newline-delimited JSON (NDJSON) file. Basically, each line in a file is a valid JSON-object containing a document you want to import. Now, I needed a way to parse all 700 markdown files and convert them into a single .ndjson file. Sanity to the rescue! Their markdown-to-sanity repo did the job beautifully.

After following the README.md you should have the CLI tool installed on your machine. For organizational purposes, I created a new directory called /blog at the root of the repository and dropped all of my markdown files in there. I also needed to bring over all of the static assets – such as images, gifs, and videos – that each blog post was referencing.

Referencing Existing Sanity Data

For each blog post, there is an author. Luckily, we already had these authors stored in our Sanity dataset. Essentially, we want to pass the author’s reference ID that Sanity has set when we create the JSON object of the blog post. Sanity provides a helpful client that you can use to fetch whatever data you need. All you need to do is pass a valid GROQ query into the fetch function.

Here’s a basic example of using the Sanity Client to fetch an author’s ID: