Taxonomies

Returns a data structure containing the site's Taxonomy objects, the terms within each Taxonomy object, and the pages to which the terms are assigned.

Conceptually, the Taxonomies method on a Site object returns a data structure such as:

taxonomy a:
- term 1:
  - page 1
  - page 2
- term 2:
  - page 1
taxonomy b:
- term 1:
  - page 2
- term 2:
  - page 1
  - page 2

[['taxonomy a']]
  'term 1' = ['page 1', 'page 2']
[['taxonomy a']]
  'term 2' = ['page 1']
[['taxonomy b']]
  'term 1' = ['page 2']
[['taxonomy b']]
  'term 2' = ['page 1', 'page 2']

{
   "taxonomy a": [
      {
         "term 1": [
            "page 1",
            "page 2"
         ]
      },
      {
         "term 2": [
            "page 1"
         ]
      }
   ],
   "taxonomy b": [
      {
         "term 1": [
            "page 2"
         ]
      },
      {
         "term 2": [
            "page 1",
            "page 2"
         ]
      }
   ]
}

For example, on a book review site you might create two taxonomies; one for genres and another for authors.

With this site configuration:

hugo.

taxonomies:
  author: authors
  genre: genres

[taxonomies]
  author = 'authors'
  genre = 'genres'

{
   "taxonomies": {
      "author": "authors",
      "genre": "genres"
   }
}

And this content structure:

content/
├── books/
│   ├── and-then-there-were-none.md --> genres: suspense
│   ├── death-on-the-nile.md        --> genres: suspense
│   └── jamaica-inn.md              --> genres: suspense, romance
│   └── pride-and-prejudice.md      --> genres: romance
└── _index.md

Conceptually, the taxonomies data structure looks like:

authors:
- achristie:
  - And Then There Were None
  - Death on the Nile
- ddmaurier:
  - Jamaica Inn
- jausten:
  - Pride and Prejudice
genres:
- suspense:
  - And Then There Were None
  - Death on the Nile
  - Jamaica Inn
- romance:
  - Jamaica Inn
  - Pride and Prejudice

[[authors]]
  achristie = ['And Then There Were None', 'Death on the Nile']
[[authors]]
  ddmaurier = ['Jamaica Inn']
[[authors]]
  jausten = ['Pride and Prejudice']
[[genres]]
  suspense = ['And Then There Were None', 'Death on the Nile', 'Jamaica Inn']
[[genres]]
  romance = ['Jamaica Inn', 'Pride and Prejudice']

{
   "authors": [
      {
         "achristie": [
            "And Then There Were None",
            "Death on the Nile"
         ]
      },
      {
         "ddmaurier": [
            "Jamaica Inn"
         ]
      },
      {
         "jausten": [
            "Pride and Prejudice"
         ]
      }
   ],
   "genres": [
      {
         "suspense": [
            "And Then There Were None",
            "Death on the Nile",
            "Jamaica Inn"
         ]
      },
      {
         "romance": [
            "Jamaica Inn",
            "Pride and Prejudice"
         ]
      }
   ]
}

To list the “suspense” books:

<ul>
  {{ range .Site.Taxonomies.genres.suspense }}
    <li><a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a></li>
  {{ end }}
</ul>

Hugo renders this to:

<ul>
  <li><a href="/books/and-then-there-were-none/">And Then There Were None</a></li>
  <li><a href="/books/death-on-the-nile/">Death on the Nile</a></li>
  <li><a href="/books/jamaica-inn/">Jamaica Inn</a></li>
</ul>

Examples #

List content with the same taxonomy term #

If you are using a taxonomy for something like a series of posts, you can list individual pages associated with the same term. For example:

<ul>
  {{ range .Site.Taxonomies.series.golang }}
    <li><a href="{{ .Page.RelPermalink }}">{{ .Page.Title }}</a></li>
  {{ end }}
</ul>

List all content in a given taxonomy #

This would be very useful in a sidebar as “featured content”. You could even have different sections of “featured content” by assigning different terms to the content.

<section id="menu">
  <ul>
    {{ range $term, $taxonomy := .Site.Taxonomies.featured }}
      <li>{{ $term }}</li>
      <ul>
        {{ range $taxonomy.Pages }}
          <li><a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a></li>
        {{ end }}
      </ul>
    {{ end }}
  </ul>
</section>

Render a site’s taxonomies #

The following example displays all terms in a site’s tags taxonomy:

<ul>
  {{ range .Site.Taxonomies.tags }}
    <li><a href="{{ .Page.Permalink }}">{{ .Page.Title }}</a> {{ .Count }}</li>
  {{ end }}
</ul>

This example will list all taxonomies and their terms, as well as all the content assigned to each of the terms.

layouts/partials/all-taxonomies.html

{{ with .Site.Taxonomies }}
  {{ $numberOfTerms := 0 }}
  {{ range $taxonomy, $terms := . }}
    {{ $numberOfTerms = len . | add $numberOfTerms }}
  {{ end }}

  {{ if gt $numberOfTerms 0 }}
    <ul>
      {{ range $taxonomy, $terms := . }}
        {{ with $terms }}
          <li>
            <a href="{{ .Page.RelPermalink }}">{{ .Page.LinkTitle }}</a>
            <ul>
              {{ range $term, $weightedPages := . }}
                <li>
                  <a href="{{ .Page.RelPermalink }}">{{ .Page.LinkTitle }}</a>
                  <ul>
                    {{ range $weightedPages }}
                      <li><a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a></li>
                    {{ end }}
                  </ul>
                </li>
              {{ end }}
            </ul>
          </li>
        {{ end }}
      {{ end }}
    </ul>
  {{ end }}
{{ end }}