Hugo Tips, Shortcodes, and Fragments

Hugo is the static site generator that is used to build the new parts of the Infinite Ink website, including this page. I use the fragments below in some of Infinite Ink’s source files.

News

2020-September-15 Hugo v0.75.1 released. To keep up with Hugo releases, see discourse.gohugo.io/c/announcements, github.com/gohugoio/hugo/releases, gohugo.io/news, old.reddit.com/r/gohugo/, or mobile.twitter.com/@GoHugoIO.

2020-August Significant updates in this article, including creating the sections ️Dates in Hugo, ️Variable names in Hugo, and Hugo docs shortcodes. And changed the title to Hugo Tips, Shortcodes, and Fragments.

Commenting in website source files

Commenting is useful for writing notes to yourself and for holding fragments that you have used in the past or may use in the future. To learn about the comment syntax of many languages, see Infinite Ink’s Commenting Code Cheatsheet.

‼	In a child block layout file, do not put a comment — or anything other than blank lines — outside a `define`-`end` container: only blank lines here {{ define "main" }} Go Template code and comments here {{ end }} only blank lines here

1. Commenting out executable code

In the Go Template language, which is also known as Go HTML, you can comment out^[1] executable code with the following single- or multi-line comment syntax.

{{/* Go HTML single-line comment */}}


{{/*
     Go HTML
     multi-line
     comment
*/}}

The following also work.

{{- /* Go HTML single-line comment */ -}}


{{- /*
     Go HTML
     multi-line
     comment
*/ -}}

Note that in this Go Template syntax, a space is required between each dash (-)^[2] and slash (/).

2. Commenting out notes and non-executable code

In a layout file or a Markdown content file, you can comment out text (such as an English-language note to yourself) or non-executable code with the following single- or multi-line comment syntax.

<!--  HTML or Markdown single-line comment -->

<!--
    HTML or Markdown
    multi-line
    comment
-->

‼	Do not use these HTML-style comments to comment out Go Template code in a Hugo layout file. If you do, Hugo will process the code and potentially generate error messages or change the layout logic.

One-off shortcodes

Shortcodes are a way to use Go Template code within a Hugo content file. Reusable and one-off shortcodes usually live in the layouts/shortcodes/ directory but, starting with Hugo 0.52, you have the option to put a shortcode directly into a content file by using an “inline shortcode.” This is especially useful for one-off shortcodes such as the ones discussed in fragment 3 and fragment 4 below.

To use inline shortcodes you need to set enableInlineShortcodes to true in your Hugo config file by putting this in your config.yaml:

enableInlineShortcodes: true

Or this in your config.toml:

enableInlineShortcodes = true

3. “Writing In Progress” inline shortcode

On Infinite Ink’s To-Do and Done Lists, in the section Writing In Progress, there is a list of articles that have not yet been published. For production — i.e. what you see — this is a list of titles without links, but for me, when I am developing the Infinite Ink website with the hugo server command, this is a list of titles with links to these unreleased articles. I do this by putting my writing-in-progress articles in a directory named content/wip/^[3]^[4] and by putting the following inline shortcode in Infinite Ink’s website-todo-done.asciidoc^[5] content file.

{{< wip.inline >}}
    
<ul class="posts">

  {{ range where .Site.RegularPages.ByTitle "Section" "eq" "wip" }}

    <li>
  
      {{ if hugo.IsProduction }}

        <em>{{ .Title }}</em>
    
      {{ else }}  <!-- not production -->

        <a href="{{ .RelPermalink }}"><em>{{ .Title }}</em></a>
    
      {{ end }}  <!-- end if-else -->
  
    </li>

  {{ end }}  <!-- end range -->

</ul>

{{< /wip.inline >}}

💡	In the highlighted line above, the `"eq"` in the phrase `"Section" "eq" "wip"` is not needed because it is the default operator in a where clause. I like to specify it anyway as a note to myself about the general syntax of the Go HTML where function.

ℹ	I do things to ensure that no WIP^[3] article is mentioned anywhere on Infinite Ink other than Infinite Ink’s To-Do and Done Lists. For example, I specify appropriate build options and the tag list in a WIP article’s front matter is commented out until it is no longer a WIP.

4. “Hugo version” inline shortcode

The Tools section of the About Infinite Ink page includes this list item:

hugo v0.74.3/extended

Each time hugo builds the Infinite Ink site, the part after “hugo ” is generated by the following fragment in Infinite Ink’s about.asciidoc^[5] content file.

v{{< hv.inline >}}
  {{- hugo.Version -}}
{{< /hv.inline >}}/extended

ℹ

The dashes^[2] in the delimiters {{- and -}} tell hugo to trim whitespace around the output of hugo.Version. These trim-whitespace delimiters must be specified exactly like this, i.e.:

a trailing space in the left delimiter,
a leading space in the right delimiter,
and no whitespace between either curly bracket and its dash.

Reusable shortcodes

The shortcodes in this section reside in my layouts/shortcodes/ directory and can be called from any content file by using the syntax specified in the comment at the top of the shortcode.

5. build-date

{{/*

Usage syntax:

  {{< build-date >}}

Path: layouts/shortcodes/build-date.html
Purpose: display current date

*/}}

{{- now.Format "2006-01-02" -}}

Here it is in action…

page built 2020-09-25
           ----------
               👆
           generated by build-date shortcode

This build-date shortcode is used in the Hugo Tutorial in step 15.2. Edit home.html.

👉️Dates in Hugo

The string 2006-01-02 in the build-date shortcode specifies the date format. Note that 2006, 01, and 02 are not a random year, month, and day. Instead they come from the Go reference date, which is Jan 2 15:04:05 2006 MST.

You can remember the reference date with the following mnemonic.

Jan 2 15:04:05 2006 MST
  1 2  3  4  5    6  -7

To learn about this, see:

6. omnicomment

{{/*

Usage syntax:

    {{< omnicomment >}}
        commented
        out
    {{< /omnicomment >}}

Forked from: github.com/gohugoio/hugoDocs/blob/master/layouts/shortcodes/todo.html
Path: layouts/shortcodes/omnicomment.html
Purpose: comment in content file written in any markup language Hugo supports
Why 1: no comment translation needed when change file from, e.g., .md to .adoc
Why 2: comment out big chunk that contains multiple markup comments^[6]

*/}}

{{ if .Inner }}{{ end }}

Note that this is a no-op shortcode.

7. years-since and years-since-phrase

{{/*

USAGE:

  {{< years-since YYYY >}}

EXAMPLE:

  {{< years-since 2009 >}}

Path: layouts/shortcodes/years-since.html
Why: as time goes on, this will still be the approximate number of years since YYYY

*/}}

{{ $thisyear := int (now.Format "2006") }}
{{ $thatyear := .Get 0 }}

{{- sub $thisyear $thatyear -}}

The above years-since shortcode returns leading whitespace so I actually use the below years-since-phrase shortcode.

❓	If you know how to remove that leading whitespace, please comment at the bottom of this page. I’ve tried a lot of things, including Hugo’s `replaceRE` and `trim` functions.

{{/*

USAGE:

  {{< years-since-phrase YYYY >}}

EXAMPLE:

  {{< years-since-phrase 2009 >}}

Path: layouts/shortcodes/years-since-phrase.html
Why: as time goes on, this phrase will still be approximately true

*/}}

{{ $thisyear := int (now.Format "2006") }}
{{ $thatyear := .Get 0 }}

{{ $difference := sub $thisyear $thatyear }}

(~{{- $difference }} years ago).

This years-since-phrase shortcode is used in the…

preamble of Infinite Ink’s #twitter-list Portal,
Endnotes section of Infinite Ink’s Commenting Code Cheatsheet
What is Markdown? section of Infinite Ink’s Ordinary and Extraordinary Markdown

👉️Variable names in Hugo

The names of Hugo variables (including parameter keys in config files and front matter)…

cannot contain a dash character (-),^[2]
can contain underscores (_) and alphanumeric characters,
and are sometimes case sensitive.

Note that variable names that a Hugo user creates in a layout file — such as $thisyear, $thatyear, and $difference — are called custom variables and must start with a dollar sign ($).

8. get-leaf-text

{{/*

USAGE:

  {{< get-leaf-text filename >}}

EXAMPLE:

  {{< get-leaf-text config.py >}}

Path: layouts/shortcodes/get-leaf-text.html
Purpose: get content of text file located in current leaf bundle

*/}}

{{ $filename := .Get 0 }}
{{ $file := .Page.Resources.GetMatch $filename }}
{{ $file.Content }}

This shortcode is used in the source of Infinite Ink’s qutebrowser’s Template config.py like this:

{{< highlight python >}}
{{< get-leaf-text config.py >}}
{{< /highlight >}}

This is an example of nested shortcodes. The highlight shortcode is discussed in fragment 10 below.

9. html4-get-bundle-image🖼️

️

{{/*

USAGE:

{{< html4-get-bundle-image "filename" "alt text" "width" "link" >}}

NOTE: parameters 1 & 2 required, parameters 3 & 4 optional

EXAMPLE 1:
{{< html4-get-bundle-image "gologo.png" "Go Logo" >}}

EXAMPLE 2:
{{< html4-get-bundle-image "gologo.png" "Go Logo" "50%" >}}

EXAMPLE 3:
{{< html4-get-bundle-image "gologo.png" "Go Logo" "25%" "https://blog.golang.org/go-brand" >}}

PATH: layouts/shortcodes/html4-get-bundle-image.html

PURPOSE: get image located in current bundle

*/}}


{{ $filename := .Get 0 }}
{{ $alt := .Get 1 }}
{{ $width := .Get 2 }}
{{ $link := .Get 3 }}

{{ $file := .Page.Resources.GetMatch $filename }}


{{ with $link }}
<a href="{{ . }}">
{{ end }}
<img
  src="{{ $file.RelPermalink }}"
  alt="{{ $alt }}"
  {{ with $width }} width="{{ . }}" {{ end }}
>
{{ if $link }}
</a>
{{ end }}

Here are three examples…

Example 1: Unspecified width

Shortcode call

{{< html4-get-bundle-image "gologo.png" "Go Logo" >}}

Example 2: 50% width

Shortcode call

{{< html4-get-bundle-image "gologo.png" "Go Logo" "50%" >}}

Example 3: 25% width and linked

Shortcode call

{{< html4-get-bundle-image "gologo.png" "Go Logo" "25%" "https://blog.golang.org/go-brand" >}}

HTML4 images vs HTML5 images

ℹ

Valid attributes of the HTML img tag changed in HTML5. For example, using width="50%" and width="25%", as I do in examples 2 and 3 above, is valid in HTML4 but invalid in HTML5. That’s why this shortcode is called html4-get-bundle-image. To learn about this, see stackoverflow.com’s Specifying width and height as percentages without skewing photo proportions in HTML.
Even though it’s invalid nowadays, it works in most (maybe all) browsers.🤷‍♀️

In both HTML4 and HTML5, it is valid to use alt="" as an img attribute, but you should do this only if an image is for decoration and is not important to the meaning of a web page. For example, the images on Infinite Ink’s #gohugo Portal and #golang Portal are specified with alt="" because they are just for decoration.

10. embed-twitter-list

{{/*

USAGE:

  {{% embed-twitter-list listname %}}

EXAMPLE:

  {{% embed-twitter-list zeitgeist %}}

Path: layouts/shortcodes/embed-twitter-list.adoc
Purpose: Embed heading and Twitter list in a page written in AsciiDoc

*/}}


{{ $listbasename := .Get 0 }}

=== @nm/lists/{{- $listbasename }}

++++
<a class="twitter-timeline" href="https://twitter.com/nm/lists/{{- $listbasename -}}?ref_src=twsrc%5Etfw">A Twitter List by @nm <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
++++

This shortcode is used in some Infinite Ink portals, for example in the #zeitgeist Portal.

‼	This shortcode uses AsciiDoc syntax and is meant to be used in a source file written in AsciiDoc and called with the `{{%` and `%}}` shortcode delimiters (not the `{{<` and `>}}` shortcode delimiters).

Built-in shortcodes

Hugo includes built-in shortcodes, which you can read about at:

gohugo.io/content-management/shortcodes/#use-hugos-built-in-shortcodes

A good way to learn about writing your own shortcodes is to look at the source code of Hugo’s built-in shortcodes. This code is available on GitHub at:

github.com/gohugoio/hugo/tree/master/tpl/tplimpl/embedded/templates/shortcodes

11. highlight

When I use Hugo’s built-in highlight shortcode and want to highlight multiple lines, I often need to look up the syntax, which can look like this:

{{< highlight html "hl_lines=3-5" >}}

html code that will be rendered with lines 3, 4, and 5 highlighted

{{< /highlight >}}

Or this:

{{< highlight toml "hl_lines=1 12 33" >}}

toml code that will be rendered with lines 1, 12, and 33 highlighted

{{< /highlight >}}

To learn about the highlight shortcode, see:

gohugo.io/content-management/shortcodes/#highlight
gohugo.io/content-management/syntax-highlighting
github.com/gohugoio/hugo/blob/master/tpl/tplimpl/embedded/templates/shortcodes/highlight.html
gohugo.io/functions/highlight/ - this Hugo function is used in the built-in highlight shortcode (it’s confusing that a Hugo shortcode and a Hugo function are both named “highlight”😕^[7])

Hugo docs shortcodes

More shortcodes are available in the repository of the Hugo Documentation in this directory:

github.com/gohugoio/hugoDocs/tree/master/layouts/shortcodes

This directory includes shortcodes for note, tip, and warning admonitions. To use one of the Hugo docs shortcodes, copy it to somewhere below your project’s layout/shortcodes/ directory, for example to one of the following directories.

layout/shortcodes/
layout/shortcodes/3rdparty/
layout/shortcodes/hugodocs/

Escaping strings in content files from Hugo processing

12. Escaping emoji codes

In step 13.2.2. Include emoji codes in Infinite Ink’s Hugo Tutorial, I wrote about the following emoji codes.

:man_astronaut:
:star:
:woman_astronaut:
:bulb:
:wrench:
:sparkles:

Since I have enableEmoji: true in my config.yaml, Hugo emojifies the above strings in a content file to:

👨‍🚀
⭐
👩‍🚀
💡
🔧
✨

So how do you write about these strings without Hugo emojifying them? There is more than one way to escape emoji codes. The way I do it is to use an HTML entity for one of the colons in each emoji code. For example:

:man_astronaut&#58;
:star&#58;
:woman_astronaut&#58;
:bulb&#58;
:wrench&#58;
:sparkles&#58;

ℹ	This trick works… in some parts of a Markdown content file, but does not work in Markdown inline code or in a Markdown code block throughout an AsciiDoc content file, but sometimes needs `[subs="replacements"]`

13. Escaping Hugo shortcodes

In a Hugo content file, shortcodes are called using either the delimiters {{< and >}} or the delimiters {{% and %}}. If you want to write about shortcodes, as I did in fragments 3, 4, 5, 6, 7, 8, 9, 10 and 11 above, you need to escape these strings from being interpreted as being part of actual shortcode calls. Hugo uses the following syntax to escape these delimiters in a content source file:

{{</* something */>}}

{{%/* something */%}}

If you use the above delimiters in a content file, they will be rendered in the destination file as:

{{< something >}}

{{% something %}}

And these strings will not be interpreted as shortcode calls.

ℹ	I learned about escaping Hugo shortcodes in the discourse.gohugo.io thread How is the Hugo Doc site showing shortcodes in code blocks?

Hugo configuration

To learn about configuring Hugo, see gohugo.io/getting-started/configuration/.

14. frontmatter

I use the following nested map, which is also known as a table,^[8] in my config.yaml because…

I want date and publishDate to mean the same thing and
if no date is specified, I want a reasonably sane date (:fileModTime) to be used rather than Hugo’s default date, which is 0001-Jaunary-01.

frontmatter:
  date: 
    - publishDate
    - :filename
    - date
    - :fileModTime
  publishDate: 
    - publishDate
    - :filename
    - date
    - :fileModTime
  lastmod: 
    - lastmod
    - :fileModTime

For more about this, see Stackoverflow.com’s Hugo Date vs PublishDate, which includes a post by n m (i.e. me😄).

The TOML syntax for this table is in fragment 16 below.

15. markup

Starting with Hugo v0.60.0^[9], the way to override Hugo’s default markup settings is to use a markup nested map in your project’s config file. Here is an excerpt of Infinite Ink’s config.yaml:

markup:
  goldmark:
    renderer:
      unsafe: true  # default is false
  highlight:
    style: tango    # default is monokai

Note that…

The colors and italics in this YAML fragment are thanks to tango-style syntax highlighting.
Without the unsafe: true setting, which is the highlighted line in this YAML fragment, raw HTML in a Goldmark-flavored Markdown source file will be replaced with  in the markdownified^[10] destination file.
A nested-map markup setting like this does not work in the front matter of a content file. These variables must be set globally.

💡	To view examples of all possible values of `markup.highlight.style`, including `monokai` and `tango`, see the Chroma Style Gallery at xyproto.github.io/splash/docs/all.html.

For more about this, see the following.

gohugo.io:
- Configure Markup
ii.com:

The TOML syntax for this markup nested map, which is also known as a table, is at the bottom of the next fragment.

16. Dividing lines for config.toml

When I use a config.toml, I like to include comments like the three highlighted lines below.

### ---> Put tables below non-tables <--- ###


# next from “One-off shortcodes” above
enableInlineShortcodes = true


# next from fragment 12 above
enableEmoji = true 


### ---> Put TOML tables below here <--- ###


# next from fragment 14 above
[frontmatter]
  date = ["publishDate", ":filename", "date", ":fileModTime"]
  publishDate = ["publishDate", ":filename", "date", ":fileModTime"]
  lastmod = ["lastmod", ":fileModTime"]


# next from fragment 15 above
[markup]

  [markup.goldmark]
    [markup.goldmark.renderer]
      unsafe = true

  [markup.highlight]
    style = "tango"


### ---> Put tables below non-tables <--- ###

I use these triple-hash comments because I have spent a lot of time debugging Hugo websites when I, for example, put a non-table at the bottom of a config.toml.⁠😩

To learn about TOML, which is an alternative to YAML, see:

For more gohugo-related links, see Infinite Ink’s #gohugo Portal.

Endnotes

1. The phrase “comment out” is discussed in english.stackexchange.com/questions/33483/when-i-say-comment-out-does-it-mean-to-uncomment-something-or-comment-it.

2. The Unicode name for the “dash” character (-) is “hyphen-minus,” but its proper name is rarely used. Instead it is usually referred to as “dash,” “hyphen,” or “minus.” Details are at Hyphen-minus - Wikipedia.

3. WIP can mean “work in progress” or “writing in progress.”

4. The front matter of some of Infinite Ink’s WIP articles include draft: true. Only the titles of the WIP articles that are not drafts are listed when I publish Infinite Ink’s To-Do and Done Lists page.

5. The file extension .asciidoc could be any of the 13 content file extensions that are known to Hugo (.ad, .adoc, .asciidoc, .htm, .html, .markdown, .md, .mdown, .mmark, .pdc, .pandoc, .org, or .rst).

6. By “multiple markup comments,” I mean markup comments that are not omnicomments.

7. Another example of a shortcode and function having the same name: the relref shortcode and relref function.

8. A nested map is also known as an associative array, a dictionary, a dict, a hash table, a hash, a map, a mapping, a named map, an object, or a table. For more about this data-serialization object, see Infinite Ink’s YAML includes Atoms, Maps, and Lists.

9. As of Hugo v0.60.0, which was released on 2019-November-27, Goldmark is the default Markdown parser, the Mmark Markdown parser is deprecated, and it was announced that the Blackfriday Markdown parser will eventually be deprecated.

10. In Hugo markdownify means convert Markdown to HTML

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