Post: Tags

Jekyll has first class support for tags and categories in blog posts.

Tag feature basically consists of three abilities:

a) adding tags to posts,
b) displaying all tags, with posts count and
c) browsing posts by tag.

Adding tags to posts

Tags for a post are defined in the post’s front matter using either the key tag for a single entry or tags for multiple entries.

Since Jekyll expects multiple items mapped to the key tags, it will automatically split a string entry if it contains whitespace. For example, while front matter tag: classic hollywood will be processed into a singular entity "classic hollywood", front matter tags: classic hollywood will be processed into an array of entries ["classic", "hollywood"].

Irrespective of the front matter key chosen(tag or tags), Jekyll stores the metadata mapped to the plural key which is exposed to Liquid templates.

Displaying Tags

displaying tags on a post

{% if page.tags.size > 0 %}
{% for tagName in page.tags %}
- {{ tagName }}
{% endfor %}
{% endif %}

displaying all tags in a site

Jekyll offers global array site.tags which contains information on all the tags.

Each element is an array as follows: [0] - tag name and [1] - all posts for the tag.

{% if site.tags.size > 0 %}
<ul>
    {% for tag in site.tags %}
    {% assign tagName = tag | first | downcase %}
    {% assign postsCount = tag | last | size %}
    <li><a href="/tags?tagName={{ tagName }}">{{ tagName }}</a>({{ postsCount }})</li>
    {% endfor %}
</ul>
{% endif %}

示例如下：

jekyll(1)
java(2)
asm(1)
agent(1)
instrumentation(1)

All tags registered in the current site are exposed to Liquid templates via site.tags. Iterating over site.tags on a page will yield another array with two items, where the first item is the name of the tag and the second item being an array of posts with that tag.

{% for tag in site.tags %}
  <p>{{ tag[0] }}</p>
  <ul>
    {% for post in tag[1] %}
      <li><a href="{{ post.url }}">{{ post.title }}</a></li>
    {% endfor %}
  </ul>
{% endfor %}