---
layout: docs
title: Collections
permalink: /docs/collections/
---

<div class="note warning">
  <h5>Collections support is unstable and may change</h5>
  <p>
    This is an experimental feature and the API may change until the feature stabilizes.
  </p>
</div>

Not everything is a post or a page. Maybe you want to document the various
methods in your open source project, members of a team, or talks at a
conference. Collections allow you to define a new type of document that behave
like Pages or Posts do normally, but also have their own unique properties and
namespace.

## Using Collections

### Step 1: Tell Jekyll to read in your collection

Add the following to your site's `_config.yml` file, replacing `my_collection`
with the name of your collection:

{% highlight yaml %}
collections:
- my_collection
{% endhighlight %}

You can optionally specify metadata for your collection in the configuration:

{% highlight yaml %}
collections:
  my_collection:
    foo: bar
{% endhighlight %}

Default attributes can also be set for a collection:

{% highlight yaml %}
defaults:
  - scope:
      path: ""
      type: my_collection
    values:
      layout: page
{% endhighlight %}

### Step 2: Add your content

Create a corresponding folder (e.g. `<source>/_my_collection`) and add
documents. YAML Front Matter is read in as data if it exists, and everything
after it is stuck in the Document's `content` attribute. If no YAML Front
Matter is provided, Jekyll will not generate the file in your collection.

<div class="note info">
  <h5>Be sure to name your directories correctly</h5>
  <p>
The folder must be named identically to the collection you defined in
your <code>_config.yml</code> file, with the addition of the preceding <code>_</code> character.
  </p>
</div>

### Step 3: Optionally render your collection's documents into independent files

If you'd like Jekyll to create a public-facing, rendered version of each
document in your collection, set the `output` key to `true` in your collection
metadata in your `_config.yml`:

{% highlight yaml %}
collections:
  my_collection:
    output: true
{% endhighlight %}

This will produce a file for each document in the collection.
For example, if you have `_my_collection/some_subdir/some_doc.md`,
it will be rendered using Liquid and the Markdown converter of your
choice and written out to `<dest>/my_collection/some_subdir/some_doc.html`.

As for posts with [Permalinks](../permalinks/), the document
URL can be customized by setting `permalink` metadata for the collection:

{% highlight yaml %}
collections:
  my_collection:
    output: true
    permalink: /awesome/:path/
{% endhighlight %}

For example, if you have `_my_collection/some_subdir/some_doc.md`, it will be
written out to `<dest>/awesome/some_subdir/some_doc/index.html`.

<div class="note info">
  <h5>Don't forget to add YAML for processing</h5>
  <p>
Files in collections that do not have front matter are treated
as static files and simply copied to their output location without
processing.
  </p>
</div>

<div class="mobile-side-scroller">
<table>
  <thead>
    <tr>
      <th>Variable</th>
      <th>Description</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>
        <p><code>collection</code></p>
      </td>
      <td>
        <p>Label of the containing collection.</p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>path</code></p>
      </td>
      <td>
        <p>Path to the document relative to the collection's directory.</p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>name</code></p>
      </td>
      <td>
        <p>The document's base filename, with every sequence of spaces
        and non-alphanumeric characters replaced by a hyphen.</p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>title</code></p>
      </td>
      <td>
        <p>The document's lowercase title (as defined in its <a href="/docs/frontmatter/">front matter</a>), with every sequence of spaces and non-alphanumeric characters replaced by a hyphen. If the document does not define a title in its <a href="/docs/frontmatter/">front matter</a>, this is equivalent to <code>name</code>.</p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>output_ext</code></p>
      </td>
      <td>
        <p>Extension of the output file.</p>
      </td>
    </tr>
  </tbody>
</table>
</div>

## Liquid Attributes

### Collections

Each collection is accessible via the `site` Liquid variable. For example, if
you want to access the `albums` collection found in `_albums`, you'd use
`site.albums`. Each collection is itself an array of documents
(e.g. `site.albums` is an array of documents, much like `site.pages` and
`site.posts`). See below for how to access attributes of those documents.

The collections are also available under `site.collections`, with the metadata
you specified in your `_config.yml` (if present) and the following information:

<div class="mobile-side-scroller">
<table>
  <thead>
    <tr>
      <th>Variable</th>
      <th>Description</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>
        <p><code>label</code></p>
      </td>
      <td>
        <p>
          The name of your collection, e.g. <code>my_collection</code>.
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>docs</code></p>
      </td>
      <td>
        <p>
          An array of <a href="#documents">documents</a>.
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>files</code></p>
      </td>
      <td>
        <p>
          An array of static files in the collection.
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>relative_directory</code></p>
      </td>
      <td>
        <p>
          The path to the collection's source directory, relative to the site
          source.
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>directory</code></p>
      </td>
      <td>
        <p>
          The full path to the collections's source directory.
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>output</code></p>
      </td>
      <td>
        <p>
          Whether the collection's documents will be output as individual
          files.
        </p>
      </td>
    </tr>
  </tbody>
</table>
</div>


### Documents

In addition to any YAML Front Matter provided in the document's corresponding
file, each document has the following attributes:

<div class="mobile-side-scroller">
<table>
  <thead>
    <tr>
      <th>Variable</th>
      <th>Description</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>
        <p><code>content</code></p>
      </td>
      <td>
        <p>
          The (unrendered) content of the document. If no YAML Front Matter is
          provided, Jekyll will not generate the file in your collection. If
          YAML Front Matter is used, then this is all the contents of the file
          after the terminating
          `---` of the front matter.
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>output</code></p>
      </td>
      <td>
        <p>
          The rendered output of the document, based on the
          <code>content</code>.
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>path</code></p>
      </td>
      <td>
        <p>
          The full path to the document's source file.
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>relative_path</code></p>
      </td>
      <td>
        <p>
          The path to the document's source file relative to the site source.
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>url</code></p>
      </td>
      <td>
        <p>
          The URL of the rendered collection. The file is only written to the
          destination when the name of the collection to which it belongs is
          included in the <code>render</code> key in the site's configuration
          file.
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p><code>collection</code></p>
      </td>
      <td>
        <p>
          The name of the document's collection.
        </p>
      </td>
    </tr>
  </tbody>
</table>
</div>

## Accessing Collection Attributes

Attributes from the YAML front matter can be accessed as data anywhere in the 
site. Using the above example for configuring a collection as `site.albums`,
one might have front matter in an individual file structured as follows (which
must use a supported markup format, and cannot be saved with a `.yaml`
extension):

{% highlight yaml %}
title: "Josquin: Missa De beata virgine and Missa Ave maris stella"
artist: "The Tallis Scholars"
director: "Peter Phillips"
works:
  - title: "Missa De beata virgine"
    composer: "Josquin des Prez"
    tracks:
      - title: "Kyrie"
        duration: "4:25"
      - title: "Gloria"
        duration: "9:53"
      - title: "Credo"
        duration: "9:09"
      - title: "Sanctus & Benedictus"
        duration: "7:47"
      - title: "Agnus Dei I, II & III"
        duration: "6:49"
{% endhighlight %}

Every album in the collection could be listed on a single page with a template:

{% highlight html %}
{% raw %}
{% for album in site.albums %}
  <h2>{{ album.title }}</h2>
  <p>Performed by {{ album.artist }}{% if album.director %}, directed by {{ album.director }}{% endif %}</p>
  {% for work in album.works %}
    <h3>{{ work.title }}</h3>
    <p>Composed by {{ work.composer }}</p>
    <ul>
    {% for track in work.tracks %}
      <li>{{ track.title }} ({{ track.duration }})</li>
    {% endfor %}
    </ul>
  {% endfor %}
{% endfor %}
{% endraw %}
{% endhighlight %}