Mapping Documents to Document Types

Contentlayer resolves the type of each document in this order:

  1. Explicit type field on the document.
  2. Matching the filePathPattern for the document type.

Explicitly Specifying Document Type

Any document can explicitly declare its type. Do this by adding a field to the document called type and using the name option from the document type definition. See here for all document type options.

Consider the following schema (document type) definition:

defineDocumentType(() => ({
  name: 'Post',
  filePathPattern: `posts/**/*.mdx`,
  // ...
}))

The name of this definition is Post. Therefore, in the content file, you can specify the Post type directly, like this (in markdown):

---
title: '...'
type: Post
# ...
---

Colocated Documents with Multiple Types

There is convenience in defining types explicitly on documents when you have multiple types in the same directory. In this case, you likely have multiple document type definitions that share the same filePathPattern option.

Say you have pages and posts, but you want them both to live in the same directory. Your config might look like this:

const Page = defineDocumentType(() => ({
  name: 'Page',
  filePathPattern: `**/*.md`,
  // ...
}))

const Post = defineDocumentType(() => ({
  name: 'Post',
  filePathPattern: `**/*.md`,
  // ...
}))

In this case, regardless of where you put a page or a post, you'd want to specify the type explicitly.

---
title: Home Page
type: Page
# ...

Staying True to filePathPattern

Note that regardless of whether or not you are explicitly defining the type on individual documents, you should still stay true to the filePathPattern option for that document type's definition.

Following the example above, if you've specified the filePathPattern as posts/**/*.mdx and the type as Post, you don't want to place a document of type Post in a directory outside posts or without an .mdx file extension. If you do, Contentlayer may process the file.

/
├── posts/
|   └── put Post documents here ...
└── pages/
    └── not here ...

Resolving Document Type with filePathPattern

When a content directory will contain only one type of document, you can avoid explicitly specifying the type by providing a unique filePathPattern option to the document type definition.

For example, consider a Post document type that would only be placed in a posts directory, which would never contain any other types. Everything in this directory would automatically be interpreted as a Post object, even if not explicitly stated.

If this is our definition:

const Post = defineDocumentType(() => ({
  name: 'Post',
  filePathPattern: `posts/**/*.md`,
  // ...
}))

Then Contentlayer's interpretation would look like this:

/
├── posts/
|   └── assumed to be Post documents
└── pages/
    └── no Post documents here

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Last edited on September 20, 2022.
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