Best way to convert HTML to a PortableText object?

Perfect! There's a dedicated package for exactly what you need. The @sanity/block-tools package (also available as @portabletext/block-tools on npm) provides the htmlToBlocks function that converts HTML to Portable Text.

Here's how to get started:

Installation:

npm install -D @portabletext/block-tools jsdom

You'll need JSDOM (or another DOM parser) since the conversion needs to parse the HTML structure.

Basic Usage:

The htmlToBlocks function handles common HTML elements like headings, paragraphs, bold, italic, and lists automatically. For a simple migration, you can use it with your Portable Text schema configuration.

Custom Rules:

If your WYSIWYG editor created more complex HTML (like custom classes, <figure> tags, or embedded images), you can define custom deserialization rules to handle specific elements. This lets you:

• Extract data from HTML attributes
• Transform elements into custom Portable Text block types
• Handle inline styles and convert them to decorators

Important Note:

The htmlToBlocks function is synchronous, so if your HTML contains images or other assets, you'll need to handle uploading those to Sanity separately and then reference them in your Portable Text blocks.

Sanity has a great course on migrating WordPress content that walks through the entire process, which should be helpful even if you're not coming from WordPress specifically.