@metalsmith/refs

A metalsmith plugin to easily refer to other files and global metadata from file.refs

Features

• Gives your files a default, but customizable identity matching its relative file path
• Substitutes a file's refs keypaths with their target file- or metadata values
• Allows tracing a file's manipulations via its id property
• Batch assign references with @metalsmith/default-values

Installation

NPM:

npm install @metalsmith/refs

Yarn:

yarn add @metalsmith/refs

Usage

Pass @metalsmith/refs to metalsmith.use :

import refs from '@metalsmith/refs'
import layouts from '@metalsmith/layouts'

metalsmith.use(refs()) // defaults
metalsmith.use(
  refs({
    // explicit defaults
    pattern: '**'
  })
)

Now you can, say, reference child documentation pages in the index src/docs/index.html:

---
id: docs_index
refs:
  # relative refs will be resolved vs the current file
  getting_started: file:./getting-started/index.html
  # absolute refs will be resolved vs metalsmith.source()
  usage_guide: file:/docs/usage-guide/index.html
---

Refs are defined in a protocol:path format. As a shortcut, not specifying the protocol: part will default to file:.

When @metalsmith/refs runs, it will substitute the refs with the actual files:

{
  'docs/index.html': {
    id: 'docs_index',
    refs: {
      getting_started: {
        id: 'docs/getting-started/index.html',
        contents: Buffer.from('...'),
        stats: {...}
      },
      usage_guide: {
        id: 'docs/usage-guide/index.html',
        contents: Buffer.from('...'),
        stats: {...}
      }
    }
  }
}

The file references are Proxy objects of the targets they refer to, i.e. they will be in sync when other plugins alter them later. To avoid circular references, you cannot access a ref's own refs.

As the example above shows, @metalsmith/refs will also add an id property to each processed file, unless you define an explicit id. By default the id is the file's path relative to metalsmith.source(), and with backslashes converted to forward slashes for cross-platform compatibility.

Plugin order

It is advised to use this plugin at the start of your build chain. Why? If you used plugins like @metalsmith/permalinks that change the file's path before this plugin, the id property will not match the source path of the file.

Using @metalsmith/refs at the start of your plugin chain gives you an easy way to trace file transforms by other plugins.

Custom ids

You can define an id property before @metalsmith/refs runs, and it will not be overwritten. In the example above, the getting-started and usage-guide pages could refer to the index with the id: protocol:

---
refs:
  docs_home: id:docs_index
---

This is useful if you wish to decouple a file's identity from its path on disk and to avoid having to commit a lot of small changes when/if you plan to reorganize source files.

Reference global metadata

Metalsmith.metadata() keys can be referenced with the metadata: protocol, e.g.:

docs/index.html

---
refs:
  navigation: metadata:navigation
  articles: metadata:collections.articles
---

As the example demonstrates dot.delimited.keypaths are also supported.

Referencing the entire metalsmith.metadata() object is not possible. Plugins like @metalsmith/in-place or @metalsmith/layouts already allow access to the global metadata in their render contexts.

Batch references by filepath

Use @metalsmith/default-values before @metalsmith/refs to automatically assign refs by glob patterns:

metalsmith
  .use(
    defaultValues([
      {
        pattern: 'docs/*/*.html',
        defaults: {
          refs: {
            docs_index: 'file:./docs/index.html',
            globalLinks: 'metadata:globalLinks'
          }
        }
      }
    ])
  )
  .use(refs())

Debug

To enable debug logs, set the DEBUG environment variable to @metalsmith/refs*:

metalsmith.env('DEBUG', '@metalsmith/refs*')

Alternatively you can set DEBUG to @metalsmith/* to debug all Metalsmith core plugins.

CLI usage

To use this plugin with the Metalsmith CLI, add @metalsmith/refs to the plugins key in your metalsmith.json file:

{
  "plugins": [
    {
      "@metalsmith/refs": {}
    }
  ]
}

License

LGPL-3.0