Custom Jekyll Frontmatter Filters

When you need to filter content by custom Frontmatter types (and not by tags/categories).

Installation:

• Copy filter_by_frontmatter.rb to your Jekyll plugin folder (default is ./_plugins).

filter_by_frontmatter:

{{ site.posts | filter_by_frontmatter:'coffee_varietal','caturra' }} -> (list of posts with the custom frontmatter 'coffee_varietal' of 'caturra') {{ site.posts | filter_by_frontmatter:'coffee_varietal','caturra' | size }} -> 5

list_by_frontmatter:

{% assign subcategories = site.posts | list_by_frontmatter: 'subcategories' %}
{% for subcategory in subcategories %}
  <li>{{subcategory}}: {{ site.posts | filter_by_frontmatter: 'subcategories',subcategory | size }}</li>
{% endfor %}

Outputs:

<ul>
  <li>subcategoryA: 1</li>
  <li>subcategoryB: 1</li>
  <li>subcategoryC: 5</li>
  ...
</ul>

Notes:

• Tested on Ruby 2.1.5
• ᕕ( ᐛ )ᕗ