Taxonomies

What is a taxonomy?

Hugo includes support for user-defined groupings of content called taxonomies. Taxonomies are classifications of logical relationships between content.

Definitions

Taxonomy

a categorization that can be used to classify content

Term

a key within the taxonomy

Value

a piece of content assigned to a term

Example taxonomy: movie website

Let’s assume you are making a website about movies. You may want to include the following taxonomies:

• Actors
• Directors
• Studios
• Genre
• Year
• Awards

Then, in each of the movies, you would specify terms for each of these taxonomies (i.e., in the front matter of each of your movie content files). From these terms, Hugo would automatically create pages for each Actor, Director, Studio, Genre, Year, and Award, with each listing all of the Movies that matched that specific Actor, Director, Studio, Genre, Year, and Award.

Movie taxonomy organization

To continue with the example of a movie site, the following demonstrates content relationships from the perspective of the taxonomy:

Actor                    <- Taxonomy
    Bruce Willis         <- Term
        The Sixth Sense  <- Value
        Unbreakable      <- Value
        Moonrise Kingdom <- Value
    Samuel L. Jackson    <- Term
        Unbreakable      <- Value
        The Avengers     <- Value
        xXx              <- Value

From the perspective of the content, the relationships would appear differently, although the data and labels used are the same:

Unbreakable                 <- Value
    Actors                  <- Taxonomy
        Bruce Willis        <- Term
        Samuel L. Jackson   <- Term
    Director                <- Taxonomy
        M. Night Shyamalan  <- Term
    ...
Moonrise Kingdom            <- Value
    Actors                  <- Taxonomy
        Bruce Willis        <- Term
        Bill Murray         <- Term
    Director                <- Taxonomy
        Wes Anderson        <- Term
    ...

Default taxonomies

Hugo natively supports taxonomies.

Without adding a single line to your site configuration file, Hugo will automatically create taxonomies for tags and categories. That would be the same as manually configuring your taxonomies as below:

taxonomies:
  category: categories
  tag: tags

[taxonomies]
  category = 'categories'
  tag = 'tags'

{
   "taxonomies": {
      "category": "categories",
      "tag": "tags"
   }
}

If you do not want Hugo to create any taxonomies, set disableKinds in your site configuration to the following:

disableKinds:
- taxonomy
- term

disableKinds = ['taxonomy', 'term']

{
   "disableKinds": [
      "taxonomy",
      "term"
   ]
}

Four other page kinds unrelated to content are robotsTXT, RSS, sitemap, and 404. Although primarily for internal use, you can specify the name when disabling one or more page kinds on your site. For example:

disableKinds:
- robotsTXT
- "404"

disableKinds = ['robotsTXT', '404']

{
   "disableKinds": [
      "robotsTXT",
      "404"
   ]
}

Default destinations

When taxonomies are used—and taxonomy templates are provided—Hugo will automatically create both a page listing all the taxonomy’s terms and individual pages with lists of content associated with each term. For example, a categories taxonomy declared in your configuration and used in your content front matter will create the following pages:

• A single page at example.com/categories/ that lists all the terms within the taxonomy
• Individual taxonomy list pages (e.g., /categories/development/) for each of the terms that shows a listing of all pages marked as part of that taxonomy within any content file’s front matter

Configure taxonomies

Custom taxonomies other than the defaults must be defined in your site configuration before they can be used throughout the site. You need to provide both the plural and singular labels for each taxonomy. For example, singular key = "plural value" for TOML and singular key: "plural value" for YAML.

Example: adding a custom taxonomy named “series”

taxonomies:
  category: categories
  series: series
  tag: tags

[taxonomies]
  category = 'categories'
  series = 'series'
  tag = 'tags'

{
   "taxonomies": {
      "category": "categories",
      "series": "series",
      "tag": "tags"
   }
}

Example: removing default taxonomies

If you want to have just the default tags taxonomy, and remove the categories taxonomy for your site, you can do so by modifying the taxonomies value in your site configuration.

taxonomies:
  tag: tags

[taxonomies]
  tag = 'tags'

{
   "taxonomies": {
      "tag": "tags"
   }
}

If you want to disable all taxonomies altogether, see the use of disableKinds in Hugo Taxonomy Defaults.

Assign terms to content

To assign one or more terms to a page, create a front matter field using the plural name of the taxonomy, then add terms to the corresponding array. For example:

---
categories:
- Category A
- Category B
tags:
- Tag A
- Tag B
title: Example
---

+++
categories = ['Category A', 'Category B']
tags = ['Tag A', 'Tag B']
title = 'Example'
+++

{
   "categories": [
      "Category A",
      "Category B"
   ],
   "tags": [
      "Tag A",
      "Tag B"
   ],
   "title": "Example"
}

Order taxonomies

A content file can assign weight for each of its associate taxonomies. Taxonomic weight can be used for sorting or ordering content in taxonomy templates and is declared in a content file’s front matter. The convention for declaring taxonomic weight is taxonomyname_weight.

The following show a piece of content that has a weight of 22, which can be used for ordering purposes when rendering the pages assigned to the “a”, “b” and “c” values of the tags taxonomy. It has also been assigned the weight of 44 when rendering the “d” category page.

Example: taxonomic weight

categories:
- d
categories_weight: 44
tags:
- a
- b
- c
tags_weight: 22
title: foo

categories = ['d']
categories_weight = 44
tags = ['a', 'b', 'c']
tags_weight = 22
title = 'foo'

{
   "categories": [
      "d"
   ],
   "categories_weight": 44,
   "tags": [
      "a",
      "b",
      "c"
   ],
   "tags_weight": 22,
   "title": "foo"
}

By using taxonomic weight, the same piece of content can appear in different positions in different taxonomies.

Add custom metadata to a taxonomy or term

If you need to add custom metadata to your taxonomy terms, you will need to create a page for that term at /content/<TAXONOMY>/<TERM>/_index.md and add your metadata in its front matter. Continuing with our ‘Actors’ example, let’s say you want to add a Wikipedia page link to each actor. Your terms pages would be something like this:

---
title: Bruce Willis
wikipedia: https://en.wikipedia.org/wiki/Bruce_Willis
---

+++
title = 'Bruce Willis'
wikipedia = 'https://en.wikipedia.org/wiki/Bruce_Willis'
+++

{
   "title": "Bruce Willis",
   "wikipedia": "https://en.wikipedia.org/wiki/Bruce_Willis"
}