zola/docs/content/documentation/templates/overview.md

+++ title = "Overview" weight = 10 +++

Zola uses the Tera template engine, which is very similar to Jinja2, Liquid and Twig.

As this documentation will only talk about how templates work in Zola, please read the Tera template documentation if you want to learn more about it first.

All templates live in the templates directory. If you are not sure what variables are available in a template, you can place {{ __tera_context }} in the template to print the whole context.

A few variables are available on all templates except feeds and the sitemap:

• config: the language aware configuration
• current_path: the path (full URL without base_url) of the current page, always starting with a /
• current_url: the full URL for the current page
• lang: the language for the current page

Config variables can be accessed like config.variable, in HTML for example with {{ config.base_url }}. The 404 template does not get current_path and current_url (this information cannot be determined).

On top of the config attributes mentioned above, it also gets config.mode which is whether it's run in build, serve or check.

Standard templates

By default, Zola will look for three templates: index.html, which is applied to the site homepage; section.html, which is applied to all sections (any HTML page generated by creating a directory within your content directory); and page.html, which is applied to all pages (any HTML page generated by creating an .md file within your content directory).

The homepage is always a section (regardless of whether it contains other pages). Thus, the index.html and section.html templates both have access to the section variables. The page.html template has access to the page variables. The page and section variables are described in more detail in the next section.

Built-in templates

Zola comes with four built-in templates: atom.xml and rss.xml (described in Feeds), sitemap.xml (described in Sitemap), and robots.txt (described in Robots.txt). Additionally, themes can add their own templates, which will be applied if not overridden. You can override built-in or theme templates by creating a template with the same name in the correct path. For example, you can override the Atom template by creating a templates/atom.xml file.

Custom templates

In addition to the standard index.html, section.html and page.html templates, you may also create custom templates by creating an .html file in the templates directory. These custom templates will not be used by default. Instead, a custom template will only be used if you apply it by setting the template front-matter variable to the path for that template (or if you include it in another template that is applied). For example, if you created a custom template for your site's About page called about.html, you could apply it to your about.md page by including the following front matter in your about.md page:

+++
title = "About Us"
template = "about.html"
+++

Custom templates are not required to live at the root of your templates directory. For example, product_pages/with_pictures.html is a valid template.

Built-in filters

Zola adds a few filters in addition to those already present in Tera.

markdown

Converts the given variable to HTML using Markdown. There are a few differences compared to page/section Markdown rendering:

• shortcodes evaluated by this filter cannot access the current rendering context: config will be available, but accessing section or page (among others) from a shortcode called within the markdown filter will prevent your site from building (see this discussion)
• lang in shortcodes will always be equal to the site's default_lang (or en otherwise) ; it should not be a problem, but if it is in most cases, but if you need to use language-aware shortcodes in this filter, please refer to the Shortcode context section of the docs.

By default, the filter will wrap all text in a paragraph. To disable this behaviour, you can pass true to the inline argument:

{{ some_text | markdown(inline=true) }}

You do not need to use this filter with page.content or section.content, the content is already rendered.

base64_encode

Encode the variable to base64.

base64_decode

Decode the variable from base64.

num_format

Format a number into its string representation.

{{ 1000000 | num_format }}
<!-- 1,000,000 -->

By default this will format the number using the locale set by config.default_language in config.toml.

To format a number for a specific locale, you can use the locale argument and pass the name of the desired locale:

{{ 1000000 | num_format(locale="en-IN") }}
<!-- 10,00,000 -->

Built-in functions

Zola adds a few Tera functions to those built-in in Tera to make it easier to develop complex sites.

File searching logic

For functions that are searching for a file on disk other than through get_page and get_section, the following logic applies.

1. The base directory is the Zola root directory, where the config.toml is
2. For the given path: if it starts with @/, replace that with content/ instead and trim any leading /
3. Search in the following locations in this order, returning the first where the file exists:
   1. $base_directory + $path
   2. $base_directory + "static/" + $path
   3. $base_directory + "content/" + $path
   4. $base_directory + $output_path + $path
   5. $base_directory + "themes" + $theme + "static/" + $path (only if using a theme)

In practice this means that @/some/image.jpg, /content/some/image.jpg and content/some/image.jpg will point to the same thing.

It will error if the path is outside the Zola directory.

get_page

Takes a path to an .md file and returns the associated page. The base path is the content directory.

{% set page = get_page(path="blog/page2.md") %}

get_section

Takes a path to an _index.md file and returns the associated section. The base path is the content directory.

{% set section = get_section(path="blog/_index.md") %}

If you only need the metadata of the section, you can pass metadata_only=true to the function:

{% set section = get_section(path="blog/_index.md", metadata_only=true) %}

get_taxonomy_url

Gets the permalink for the taxonomy item found.

{% set url = get_taxonomy_url(kind="categories", name=page.taxonomies.category, lang=page.lang) %}

name will almost always come from a variable but in case you want to do it manually, the value should be the same as the one in the front matter, not the slugified version.

lang (optional) default to config.default_language in config.toml

required (optional) if a taxonomy is defined but there isn't any content that uses it then throw an error. Defaults to true.

get_taxonomy

Gets the whole taxonomy of a specific kind.

{% set categories = get_taxonomy(kind="categories") %}

The type of the output is:

kind: TaxonomyConfig;
items: Array<TaxonomyTerm>;

lang (optional) default to config.default_language in config.toml

required (optional) if a taxonomy is defined but there isn't any content that uses it then throw an error. Defaults to true.

See the Taxonomies documentation for a full documentation of those types.

get_url

Gets the permalink for the given path. If the path starts with @/, it will be treated as an internal link like the ones used in Markdown, starting from the root content directory as well as validated.

{% set url = get_url(path="@/blog/_index.md") %}

It accepts an optional parameter lang in order to compute a language-aware URL in multilingual websites. Assuming config.base_url is "http://example.com", the following snippet will:

• return "http://example.com/blog/" if config.default_language is "en"
• return "http://example.com/en/blog/" if config.default_language is not "en" and "en" appears in config.languages
• fail otherwise, with the error message "'en' is not an authorized language (check config.languages)."

{% set url = get_url(path="@/blog/_index.md", lang="en") %}

This can also be used to get the permalinks for static assets, for example if we want to link to the file that is located at static/css/app.css:

{{/* get_url(path="css/app.css") */}}

By default, assets will not have a trailing slash. You can force one by passing trailing_slash=true to the get_url function. An example is:

{{/* get_url(path="css/app.css", trailing_slash=true) */}}

In the case of non-internal links, you can also add a cachebust of the format ?h=<sha256> at the end of a URL by passing cachebust=true to the get_url function. In this case, the path will need to resolve to an actual file. See File Searching Logic for details.

get_file_hash

Returns the hash digest (SHA-256, SHA-384 or SHA-512) of a file.

It can take the following arguments:

• path: mandatory, see File Searching Logic for details
• sha_type: optional, one of 256, 384 or 512, defaults to 384
• base64: optional, true or false, defaults to true. Whether to encode the hash as base64

{{/* get_file_hash(path="static/js/app.js", sha_type=256) */}}

The function can also output a base64-encoded hash value when its base64 parameter is set to true. This can be used to implement subresource integrity.

<script src="{{/* get_url(path="static/js/app.js") */}}"
  integrity="sha384-{{ get_file_hash(path="static/js/app.js", sha_type=384, base64=true) | safe }}"></script>

Do note that subresource integrity is typically used when using external scripts, which get_file_hash does not support.

get_image_metadata

Gets metadata for an image. This supports common formats like JPEG, PNG, WebP, BMP, GIF as well as SVG.

It can take the following arguments:

• path: mandatory, see File Searching Logic for details
• allow_missing: optional, true or false, defaults to false. Whether a missing file should raise an error or not.

The method returns a map containing width, height and format (the lowercased value as string).

  {% set meta = get_image_metadata(path="...") %}
  Our image (.{{meta.format}}) has format is {{ meta.width }}x{{ meta.height }}

load_data

Loads data from a file, URL, or string literal. Supported file types include toml, json, csv, bibtex and xml and only supports UTF-8 encoding.

Any other file type will be loaded as plain text.

The path argument specifies the path to a local data file, according to the File Searching Logic.

{% set data = load_data(path="content/blog/story/data.toml") %}

Alternatively, the url argument specifies the location of a remote URL to load.

{% set data = load_data(url="https://en.wikipedia.org/wiki/Commune_of_Paris") %}

Alternatively, the literal argument specifies an object literal. Note: if the format argument is not specified, then plain text will be what is assumed.

{% set data = load_data(literal='{"name": "bob"}', format="json") %}
{{ data["name"] }}

Note: the required parameter has no effect when used in combination with the literal argument.

The optional required boolean argument can be set to false so that missing data (HTTP error or local file not found) does not produce an error, but returns a null value instead. However, permission issues with a local file and invalid data that could not be parsed to the requested data format will still produce an error even with required=false.

The snippet below outputs the HTML from a Wikipedia page, or "No data found" if the page was not reachable, or did not return a successful HTTP code:

{% set data = load_data(url="https://en.wikipedia.org/wiki/Commune_of_Paris", required=false) %}
{% if data %}{{ data | safe }}{% else %}No data found{% endif %}

The optional format argument allows you to specify and override which data type is contained within the specified file or URL. Valid entries are toml, json, csv, bibtex, xml or plain. If the format argument isn't specified, then the path extension is used. In the case of a literal, plain is assumed if format is unspecified.

{% set data = load_data(path="content/blog/story/data.txt", format="json") %}

Use the plain format for when your file has a supported extension but you want to load it as plain text.

For toml, json and xml, the data is loaded into a structure matching the original data file; however, for csv there is no native notion of such a structure. Instead, the data is separated into a data structure containing headers and records. See the example below to see how this works.

In the template:

{% set data = load_data(path="content/blog/story/data.csv") %}

In the content/blog/story/data.csv file:

Number, Title
1,Gutenberg
2,Printing

The equivalent json value of the parsed data would be stored in the data variable in the template:

{
    "headers": ["Number", "Title"],
    "records": [
        ["1", "Gutenberg"],
        ["2", "Printing"]
    ],
}

The bibtex format loads data into a structure matching the format used by the nom-bibtex crate. The following is an example of data in bibtex format:

@preamble{"A bibtex preamble" # " this is."}

@Comment{
    Here is a comment.
}

Another comment!

@string(name = "Vincent Prouillet")
@string(github = "https://github.com/getzola/zola")

@misc {my_citation_key,
    author= name,
    title = "Zola",
    note = "github: " # github
}                                                    }

The following is the json-equivalent format of the produced bibtex data structure:

{
    "preambles": ["A bibtex preamble this is."],
    "comments": ["Here is a comment.", "Another comment!"],
    "variables": {
        "name": "Vincent Prouillet",
        "github": "https://github.com/getzola/zola"
    },
    "bibliographies": [
        {
            "entry_type": "misc",
            "citation_key": "my_citation_key",
            "tags": {
                "author": "Vincent Prouillet",
                "title": "Zola",
                "note": "github: https://github.com/getzola/zola"
            }
        }
    ]
}

Finally, the bibtex data can be accessed from the template as follows:

{% set tags = data.bibliographies[0].tags %}
This was generated using {{ tags.title }}, authored by {{ tags.author }}.

Remote content

Instead of using a file, you can load data from a remote URL. This can be done by specifying a url parameter to load_data rather than path.

{% set response = load_data(url="https://api.github.com/repos/getzola/zola") %}
{{ response }}

By default, the response body will be returned with no parsing. This can be changed by using the format argument as below.

{% set response = load_data(url="https://api.github.com/repos/getzola/zola", format="json") %}
{{ response }}

When no other parameters are specified the URL will always be retrieved using a HTTP GET request. Using the parameter method, since version 0.14.0, you can also choose to retrieve the URL using a POST request.

When using method="POST" you can also use the parameters body and content_type. The parameter body is the actual contents sent in the POST request. The parameter content_type should be the mimetype of the body.

This example will make a POST request to the kroki service to generate a SVG.

{% set postdata = load_data(url="https://kroki.io/blockdiag/svg", format="plain", method="POST" ,content_type="text/plain", body="blockdiag {
  'Doing POST' -> 'using load_data'
  'using load_data' -> 'can generate' -> 'block diagrams';
  'using load_data' -> is -> 'very easy!';

  'Doing POST' [color = 'greenyellow'];
  'block diagrams' [color = 'pink'];
  'very easy!' [color = 'orange'];
}")%}
{{postdata|safe}}

If you need additional handling for the HTTP headers, you can use the headers parameter. You might need this parameter when the resource requires authentication or require passing additional parameters via special headers. Please note that the headers will be appended to the default headers set by Zola itself instead of replacing them.

This example will make a POST request to the GitHub markdown rendering service.

{% set postdata = load_data(url="https://api.github.com/markdown", format="plain", method="POST", content_type="application/json", headers=["accept=application/vnd.github.v3+json"], body='{"text":"headers support added in #1710, commit before it: b3918f124d13ec1bedad4860c15a060dd3751368","context":"getzola/zola","mode":"gfm"}')%}
{{postdata|safe}}

The following example shows how to send a GraphQL query to GitHub (requires authentication). If you want to try this example on your own machine, you need to provide a GitHub PAT (Personal Access Token), you can acquire the access token at this link: https://github.com/settings/tokens and then set GITHUB_TOKEN environment variable to the access token you have obtained.

{% set token = get_env(name="GITHUB_TOKEN") %}
{% set postdata = load_data(url="https://api.github.com/graphql", format="json", method="POST" ,content_type="application/json", headers=["accept=application/vnd.github.v4.idl", "authentication=Bearer " ~ token], body='{"query":"query { viewer { login }}"}')%}
{{postdata|safe}}

In case you need to specify multiple headers with the same name, you can specify them like this:

headers=["accept=application/json,text/html"]

Which is equivalent to two Accept headers with application/json and text/html.

If it doesn't work, you can instead specify the headers multiple times to achieve a similar effect:

headers=["accept=application/json", "accept=text/html"]

Data caching

Data file loading and remote requests are cached in memory during the build, so multiple requests aren't made to the same endpoint. URLs are cached based on the URL, and data files are cached based on the file modified time. The format is also taken into account when caching, so a request will be sent twice if it's loaded with two different formats.

trans

Gets the translation of the given key, for the default_language, the language given or the active language:

{{/* trans(key="title") */}}
{{/* trans(key="title", lang="fr") */}}
{{/* trans(key="title", lang=lang) */}}

resize_image

Resizes an image file. Please refer to Content / Image Processing for complete documentation.