Data templates

Hugo supports loading data from YAML, JSON, XML, and TOML files located in the data directory at the root of your Hugo project.

The data directory

The data directory should store additional data for Hugo to use when generating your site.

Data files are not for generating standalone pages. They should supplement content files by:

Extending the content when the front matter fields grow out of control, or
Showing a larger dataset in a template (see the example below).

In both cases, it’s a good idea to outsource the data in their (own) files.

These files must be YAML, JSON, XML, or TOML files (using the .yml, .yaml, .json, .xml, or .toml extension). The data will be accessible as a map in the .Site.Data variable.

To access the data using the site.Data.filename notation, the file name must begin with an underscore or a Unicode letter, followed by zero or more underscores, Unicode letters, or Unicode digits. For example:

123.json - Invalid
x123.json - Valid
_123.json - Valid

To access the data using the index function, the file name is irrelevant. For example:

Data file	Template code
`123.json`	`{{ index .Site.Data "123" }}`
`x123.json`	`{{ index .Site.Data "x123" }}`
`_123.json`	`{{ index .Site.Data "_123" }}`
`x-123.json`	`{{ index .Site.Data "x-123" }}`

Data files in themes

Data Files can also be used in themes.

However, note that the theme data files are merged with the project directory taking precedence. That is, Given two files with the same name and relative path, the data in the file in the root project data directory will override the data from the file in the themes/<THEME>/data directory for keys that are duplicated).

Therefore, theme authors should be careful not to include data files that could be easily overwritten by a user who decides to customize a theme. For theme-specific data items that shouldn’t be overridden, it can be wise to prefix the folder structure with a namespace; e.g. mytheme/data/<THEME>/somekey/.... To check if any such duplicate exists, run hugo with the -v flag.

The keys in the map created with data templates from data files will be a dot-chained set of path, filename, and key in the file (if applicable).

This is best explained with an example:

Examples

Jaco Pastorius’ Solo Discography

Jaco Pastorius was a great bass player, but his solo discography is short enough to use as an example. John Patitucci is another bass giant.

The example below is a bit contrived, but it illustrates the flexibility of data Files. This example uses TOML as its file format with the two following data files:

data/jazz/bass/jacopastorius.toml
data/jazz/bass/johnpatitucci.toml

jacopastorius.toml contains the content below. johnpatitucci.toml contains a similar list:

data/jazz/bass/jacopastorius.

discography:
- 1974 - Modern American Music … Period! The Criteria Sessions
- 1974 - Jaco
- 1976 - Jaco Pastorius
- 1981 - Word of Mouth
- 1981 - The Birthday Concert (released in 1995)
- 1982 - Twins I & II (released in 1999)
- 1983 - Invitation
- 1986 - Broadway Blues (released in 1998)
- 1986 - Honestly Solo Live (released in 1990)
- 1986 - Live In Italy (released in 1991)
- 1986 - Heavy'n Jazz (released in 1992)
- 1991 - Live In New York City, Volumes 1-7.
- 1999 - Rare Collection (compilation)
- '2003 - Punk Jazz: The Jaco Pastorius Anthology (compilation)'
- 2007 - The Essential Jaco Pastorius (compilation)

discography = ['1974 - Modern American Music … Period! The Criteria Sessions', '1974 - Jaco', '1976 - Jaco Pastorius', '1981 - Word of Mouth', '1981 - The Birthday Concert (released in 1995)', '1982 - Twins I & II (released in 1999)', '1983 - Invitation', '1986 - Broadway Blues (released in 1998)', '1986 - Honestly Solo Live (released in 1990)', '1986 - Live In Italy (released in 1991)', "1986 - Heavy'n Jazz (released in 1992)", '1991 - Live In New York City, Volumes 1-7.', '1999 - Rare Collection (compilation)', '2003 - Punk Jazz: The Jaco Pastorius Anthology (compilation)', '2007 - The Essential Jaco Pastorius (compilation)']

{
   "discography": [
      "1974 - Modern American Music … Period! The Criteria Sessions",
      "1974 - Jaco",
      "1976 - Jaco Pastorius",
      "1981 - Word of Mouth",
      "1981 - The Birthday Concert (released in 1995)",
      "1982 - Twins I \u0026 II (released in 1999)",
      "1983 - Invitation",
      "1986 - Broadway Blues (released in 1998)",
      "1986 - Honestly Solo Live (released in 1990)",
      "1986 - Live In Italy (released in 1991)",
      "1986 - Heavy'n Jazz (released in 1992)",
      "1991 - Live In New York City, Volumes 1-7.",
      "1999 - Rare Collection (compilation)",
      "2003 - Punk Jazz: The Jaco Pastorius Anthology (compilation)",
      "2007 - The Essential Jaco Pastorius (compilation)"
   ]
}

The list of bass players can be accessed via .Site.Data.jazz.bass, a single bass player by adding the file name without the suffix, e.g. .Site.Data.jazz.bass.jacopastorius.

You can now render the list of recordings for all the bass players in a template:

{{ range $.Site.Data.jazz.bass }}
  {{ partial "artist.html" . }}
{{ end }}

And then in the partials/artist.html:

<ul>
{{ range .discography }}
  <li>{{ . }}</li>
{{ end }}
</ul>

Discover a new favorite bass player? Just add another .toml file in the same directory.

Accessing named values in a data file

Assume you have the following data structure in your user0123 data file located directly in data/:

data/user0123.

Achievements:
- Can create a Key, Value list from Data File
- Learns Hugo
- Reads documentation
Name: User0123
Short Description: He is a **jolly good** fellow.

Achievements = ['Can create a Key, Value list from Data File', 'Learns Hugo', 'Reads documentation']
Name = 'User0123'
'Short Description' = 'He is a **jolly good** fellow.'

{
   "Achievements": [
      "Can create a Key, Value list from Data File",
      "Learns Hugo",
      "Reads documentation"
   ],
   "Name": "User0123",
   "Short Description": "He is a **jolly good** fellow."
}

You can use the following code to render the Short Description in your layout:

<div>Short Description of {{ .Site.Data.user0123.Name }}: <p>{{ index .Site.Data.user0123 "Short Description" | markdownify }}</p></div>

Note the use of the markdownify function. This will send the description through the Markdown rendering engine.

Remote data

Retrieve remote data using these template functions:

LiveReload with data files

There is no chance to trigger a LiveReload when the content of a URL changes. However, when a local file changes (i.e., data/* and themes/<THEME>/data/*), a LiveReload will be triggered. Symlinks are not supported. Note too that because downloading data takes a while, Hugo stops processing your Markdown files until the data download has been completed.

Examples of data-driven content

Photo gallery JSON powered: https://github.com/pcdummy/hugo-lightslider-example.
GitHub Starred Repositories in a post using data-driven content in a custom short code.
Importing exported social media data from popular services using https://github.com/ttybitnik/diego.