Portable Text Conversion

Portable Text Conversion

Convert external content (HTML, Markdown) into Portable Text for Sanity. Three main approaches:

1. markdownToPortableText — Convert Markdown directly using @portabletext/markdown (recommended for Markdown)
2. htmlToBlocks — Parse HTML into PT blocks using @portabletext/block-tools (for HTML migration)
3. Manual construction — Build PT blocks directly from any source (APIs, databases, etc.)

Portable Text Specification

Understand the target format before converting. PT is an array of blocks:

[  {    "_type": "block",    "_key": "abc123",    "style": "normal",    "children": [      {"_type": "span", "_key": "def456", "text": "Hello ", "marks": []},      {"_type": "span", "_key": "ghi789", "text": "world", "marks": ["strong"]}    ],    "markDefs": []  },  {    "_type": "block",    "_key": "jkl012",    "style": "h2",    "children": [      {"_type": "span", "_key": "mno345", "text": "A heading", "marks": []}    ],    "markDefs": []  },  {    "_type": "image",    "_key": "pqr678",    "asset": {"_type": "reference", "_ref": "image-abc-200x200-png"}  }]

Key rules:

• Every block and span needs _key (unique within the array)
• _type: "block" is for text blocks; custom types use their own _type
• markDefs holds annotation data; marks on spans reference markDefs[*]._key or are decorator strings
• Lists use listItem ("bullet" | "number") and level (1, 2, 3...) on regular blocks

Conversion Rules

Read the rule file matching your source format:

• Markdown → Portable Text: rules/markdown-to-pt.md — @portabletext/markdown with markdownToPortableText (recommended)
• HTML → Portable Text: rules/html-to-pt.md — @portabletext/block-tools with htmlToBlocks
• Manual PT Construction: rules/manual-construction.md — build blocks programmatically from any source

Note: @sanity/block-tools is the legacy package name. Always use @portabletext/block-tools for new projects. The API is the same.