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    <- Content
        Unbreakable      <- Content
        Moonrise Kingdom <- Content
    Samuel L. Jackson    <- Term
        Unbreakable      <- Content
        The Avengers     <- Content
        xXx              <- Content

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

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

Hugo Taxonomy Defaults

Hugo natively supports taxonomies.

Without adding a single line to your site’s configuration file, Hugo will automatically create taxonomies for tags and categories. If you do not want Hugo to create any taxonomies, set disableKinds in your site’s configuration to the following:

disableKinds = ["taxonomy","taxonomyTerm"]

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

Taxonomies must be defined in your website 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: TOML Taxonomy Configuration

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

Example: YAML Taxonomy Configuration

taxonomies:
  tag: "tags"
  category: "categories"
  series: "series"

Preserve Taxonomy Values

By default, taxonomy names are normalized.

Therefore, if you want to have a taxonomy term with special characters such as Gérard Depardieu instead of Gerard Depardieu, set the value for preserveTaxonomyNames to true in your site configuration. Hugo will then preserve special characters in taxonomy values but will still title-ize the values for titles and normalize them in URLs.

Note that if you use preserveTaxonomyNames and intend to manually construct URLs to the archive pages, you will need to pass the taxonomy values through the urlize template function.

Add Taxonomies to Content

Once a taxonomy is defined at the site level, any piece of content can be assigned to it, regardless of content type or content section.

Assigning content to a taxonomy is done in the front matter. Simply create a variable with the plural name of the taxonomy and assign all terms you want to apply to the instance of the content type.

Example: TOML Front Matter with Taxonomies

+++
title = "Hugo: A fast and flexible static site generator"
tags = [ "Development", "Go", "fast", "Blogging" ]
categories = [ "Development" ]
series = [ "Go Web Dev" ]
slug = "hugo"
project_url = "https://github.com/gohugoio/hugo"
+++

Example: YAML Front Matter with Taxonomies

---
title: "Hugo: A fast and flexible static site generator"
tags: ["Development", "Go", "fast", "Blogging"]
categories: ["Development"]
series: ["Go Web Dev"]
slug: "hugo"
project_url: "https://github.com/gohugoio/hugo"
---

Example: JSON Front Matter with Taxonomies

{
    "title": "Hugo: A fast and flexible static site generator",
    "tags": [
        "Development",
        "Go",
        "fast",
        "Blogging"
    ],
    "categories" : [
        "Development"
    ],
    "series" : [
        "Go Web Dev"
    ],
    "slug": "hugo",
    "project_url": "https://github.com/gohugoio/hugo"
}

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 list templates and is declared in a content file’s front matter. The convention for declaring taxonomic weight is taxonomyname_weight.

The following TOML and YAML examples 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: TOML Taxonomic weight

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

Example: YAML Taxonomic weight

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

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

Add custom metadata to a Taxonomy 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 it’s 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"
  ---

You can later use your custom metadata as shown in the Taxonomy Terms Templates documentation.