Zola borrows the concept of shortcodes from WordPress. In our case, a shortcode corresponds to a template defined in the templates/shortcodes directory or a built-in one that can be used in a Markdown file. If you want to use something similar to shortcodes in your templates, try Tera macros.

Broadly speaking, Zola's shortcodes cover two distinct use cases:

• Inject more complex HTML: Markdown is good for writing, but it isn't great when you need add inline HTML or styling.
• Ease repetitive data based tasks: when you have external data that you want to display in your page's body.

The latter may also be solved by writing HTML, however Zola allows the use of Markdown based shortcodes which end in .md rather than .html. This may be particularly useful if you want to include headings generated by the shortcode in the table of contents.

Writing a shortcode 

Let's write a shortcode to embed YouTube videos as an example. In a file called youtube.html in the templates/shortcodes directory, paste the following:

<div {% if class %}class="{{class}}"{% endif %}>
    <iframe
        src="https://www.youtube.com/embed/{{id}}{% if autoplay %}?autoplay=1{% endif %}"
        webkitallowfullscreen
        mozallowfullscreen
        allowfullscreen>
    </iframe>
</div>

This template is very straightforward: an iframe pointing to the YouTube embed URL wrapped in a <div>. In terms of input, this shortcode expects at least one variable: id. Because the other variables are in an if statement, they are optional.

That's it. Zola will now recognise this template as a shortcode named youtube (the filename minus the .html extension).

The Markdown renderer will wrap an inline HTML node such as <a> or <span> into a paragraph. If you want to disable this behaviour, wrap your shortcode in a <div>.

A Markdown based shortcode in turn will be treated as if what it returned was part of the page's body. If we create books.md in templates/shortcodes for example:

{% set data = load_data(path=path) -%}
{% for book in data.books %}
### {{ book.title }}

{{ book.description | safe }}
{% endfor %}

This will create a shortcode books with the argument path pointing to a .toml file where it loads lists of books with titles and descriptions. They will flow with the rest of the document in which books is called.

Shortcodes are rendered before the page's Markdown is parsed so they don't have access to the page's table of contents. Because of that, you also cannot use the get_page/get_section/get_taxonomy global functions. It might work while running zola serve because it has been loaded but it will fail during zola build.

Using shortcodes 

There are two kinds of shortcodes:

• ones that do not take a body, such as the YouTube example above
• ones that do, such as one that styles a quote

In both cases, the arguments must be named and they will all be passed to the template.

Lastly, a shortcode name (and thus the corresponding .html file) as well as the argument names can only contain numbers, letters and underscores, or in Regex terms [0-9A-Za-z_]. Although theoretically an argument name could be a number, it will not be possible to use such an argument in the template.

Argument values can be of one of five types:

• string: surrounded by double quotes, single quotes or backticks
• bool: true or false
• float: a number with a decimal point (e.g., 1.2)
• integer: a whole number or its negative counterpart (e.g., 3)
• array: an array of any kind of value, except arrays

Malformed values will be silently ignored.

Both types of shortcode will also get either a page or section variable depending on where they were used and a config variable. These values will overwrite any arguments passed to a shortcode so these variable names should not be used as argument names in shortcodes.

Shortcodes without body 

Simply call the shortcode as if it was a Tera function in a variable block. All the examples below are valid calls of the YouTube shortcode.

Here is a YouTube video:

{{ youtube(id="dQw4w9WgXcQ") }}

{{ youtube(id="dQw4w9WgXcQ", autoplay=true) }}

An inline {{ youtube(id="dQw4w9WgXcQ", autoplay=true, class="youtube") }} shortcode

Note that if you want to have some content that looks like a shortcode but not have Zola try to render it, you will need to escape it by using {{/* and */}} instead of {{ and }}.

Shortcodes with body 

Let's imagine that we have the following shortcode quote.html template:

<blockquote>
    {{ body }} <br>
    -- {{ author}}
</blockquote>

We could use it in our Markdown file like so:

As someone said:

{% quote(author="Vincent") %}
A quote
{% end %}

The body of the shortcode will be automatically passed down to the rendering context as the body variable and needs to be on a new line.

If you want to have some content that looks like a shortcode but not have Zola try to render it, you will need to escape it by using {%/* and */%} instead of {% and %}. You won't need to escape anything else until the closing tag.

Invocation Count 

Every shortcode context is passed in a variable named nth that tracks how many times a particular shortcode has been invoked in a Markdown file. Given a shortcode true_statement.html template:

<p id="number{{ nth }}">{{ value }} is equal to {{ nth }}.</p>

It could be used in our Markdown as follows:

{{ true_statement(value=1) }}
{{ true_statement(value=2) }}

This is useful when implementing custom markup for features such as sidenotes or end notes.