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Markdown
421 lines
16 KiB
Markdown
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title = "Overview"
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weight = 10
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+++
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Zola uses the [Tera](https://tera.netlify.com) template engine, which is very similar
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to Jinja2, Liquid and Twig.
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As this documentation will only talk about how templates work in Zola, please read
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the [Tera template documentation](https://tera.netlify.com/docs#templates) if you want
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to learn more about it first.
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All templates live in the `templates` directory. If you are not sure what variables are available in a template,
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you can place `{{ __tera_context }}` in the template to print the whole context.
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A few variables are available on all templates except feeds and the sitemap:
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- `config`: the [configuration](@/documentation/getting-started/configuration.md) without any modifications
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- `current_path`: the path (full URL without `base_url`) of the current page, always starting with a `/`
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- `current_url`: the full URL for the current page
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- `lang`: the language for the current page
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Config variables can be accessed like `config.variable`, in HTML for example with `{{ config.base_url }}`.
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The 404 template does not get `current_path` and `current_url` (this information cannot be determined).
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## Standard templates
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By default, Zola will look for three templates: `index.html`, which is applied
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to the site homepage; `section.html`, which is applied to all sections (any HTML
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page generated by creating a directory within your `content` directory); and
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`page.html`, which is applied to all pages (any HTML page generated by creating an
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`.md` file within your `content` directory).
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The homepage is always a section (regardless of whether it contains other pages).
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Thus, the `index.html` and `section.html` templates both have access to the
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section variables. The `page.html` template has access to the page variables.
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The page and section variables are described in more detail in the next section.
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## Built-in templates
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Zola comes with four built-in templates: `atom.xml` and `rss.xml` (described in
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[Feeds](@/documentation/templates/feeds/index.md)), `sitemap.xml` (described in [Sitemap](@/documentation/templates/sitemap.md)),
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and `robots.txt` (described in [Robots.txt](@/documentation/templates/robots.md)).
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Additionally, themes can add their own templates, which will be applied if not
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overridden. You can override built-in or theme templates by creating a template with
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the same name in the correct path. For example, you can override the Atom template by
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creating a `templates/atom.xml` file.
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## Custom templates
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In addition to the standard `index.html`, `section.html` and `page.html` templates,
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you may also create custom templates by creating an `.html` file in the `templates`
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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:
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```md
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+++
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title = "About Us"
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template = "about.html"
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+++
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```
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Custom templates are not required to live at the root of your `templates` directory.
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For example, `product_pages/with_pictures.html` is a valid template.
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## Built-in filters
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Zola adds a few filters in addition to [those](https://tera.netlify.com/docs/#filters) already present
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in Tera.
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### markdown
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Converts the given variable to HTML using Markdown. Please note that 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](https://github.com/getzola/zola/pull/1358).
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By default, the filter will wrap all text in a paragraph. To disable this behaviour, you can
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pass `true` to the inline argument:
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```jinja2
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{{ some_text | markdown(inline=true) }}
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```
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You do not need to use this filter with `page.content` or `section.content`, the content is already rendered.
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### base64_encode
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Encode the variable to base64.
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### base64_decode
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Decode the variable from base64.
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### num_format
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Format a number into its string representation.
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```jinja2
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{{ 1000000 | num_format }}
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<!-- 1,000,000 -->
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```
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By default this will format the number using the locale set by `config.default_language` in config.toml.
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To format a number for a specific locale, you can use the `locale` argument and pass the name of the desired locale:
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```jinja2
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{{ 1000000 | num_format(locale="en-IN") }}
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<!-- 10,00,000 -->
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```
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## Built-in functions
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Zola adds a few Tera functions to [those built-in in Tera](https://tera.netlify.com/docs#built-in-functions)
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to make it easier to develop complex sites.
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### File searching logic
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For functions that are searching for a file on disk other than through `get_page` and `get_section`, the following
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logic applies.
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1. The base directory is the Zola root directory, where the `config.toml` is
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2. For the given path: if it starts with `@/`, replace that with `content/` instead and trim any leading `/`
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3. Search in the following 3 or 4 locations in this order, returning the first where the file exists:
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a. $base_directory + $path
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b. $base_directory + "static/" + $path
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c. $base_directory + "content/" + $path
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d. $base_directory + "themes" + $theme + "static/" + $path only if using a theme
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In practice this means that `@/some/image.jpg`, `/content/some/image.jpg` and `content/some/image.jpg` will point to the
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same thing.
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It will error if the path is outside the Zola directory.
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### `get_page`
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Takes a path to an `.md` file and returns the associated page. The base path is the `content` directory.
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```jinja2
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{% set page = get_page(path="blog/page2.md") %}
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```
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### `get_section`
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Takes a path to an `_index.md` file and returns the associated section. The base path is the `content` directory.
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```jinja2
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{% set section = get_section(path="blog/_index.md") %}
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```
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If you only need the metadata of the section, you can pass `metadata_only=true` to the function:
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```jinja2
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{% set section = get_section(path="blog/_index.md", metadata_only=true) %}
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```
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### `get_taxonomy_url`
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Gets the permalink for the taxonomy item found.
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```jinja2
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{% set url = get_taxonomy_url(kind="categories", name=page.taxonomies.category, lang=page.lang) %}
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```
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`name` will almost always come from a variable but in case you want to do it manually,
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the value should be the same as the one in the front matter, not the slugified version.
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`lang` (optional) default to `config.default_language` in config.toml
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### `get_taxonomy`
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Gets the whole taxonomy of a specific kind.
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```jinja2
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{% set categories = get_taxonomy(kind="categories") %}
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```
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The type of the output is:
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```ts
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kind: TaxonomyConfig;
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items: Array<TaxonomyTerm>;
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```
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`lang` (optional) default to `config.default_language` in config.toml
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See the [Taxonomies documentation](@/documentation/templates/taxonomies.md) for a full documentation of those types.
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### `get_url`
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Gets the permalink for the given path.
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If the path starts with `@/`, it will be treated as an internal link like the ones used in Markdown,
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starting from the root `content` directory as well as validated.
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```jinja2
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{% set url = get_url(path="@/blog/_index.md") %}
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```
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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:
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- return `"http://example.com/blog/"` if `config.default_language` is `"en"`
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- return `"http://example.com/en/blog/"` if `config.default_language` is **not** `"en"` and `"en"` appears in `config.languages`
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- fail otherwise, with the error message `"'en' is not an authorized language (check config.languages)."`
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```jinja2
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{% set url = get_url(path="@/blog/_index.md", lang="en") %}
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```
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This can also be used to get the permalinks for static assets, for example if
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we want to link to the file that is located at `static/css/app.css`:
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```jinja2
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{{/* get_url(path="static/css/app.css") */}}
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```
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By default, assets will not have a trailing slash. You can force one by passing `trailing_slash=true` to the `get_url` function.
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An example is:
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```jinja2
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{{/* get_url(path="static/css/app.css", trailing_slash=true) */}}
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```
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In the case of non-internal links, you can also add a cachebust of the format `?h=<sha256>` at the end of a URL
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by passing `cachebust=true` to the `get_url` function. In this case, the path will need to resolve to an actual file.
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See [File Searching Logic](@/documentation/templates/overview.md#file-searching-logic) for details.
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### `get_file_hash`
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Returns the hash digest (SHA-256, SHA-384 or SHA-512) of a file.
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It can take the following arguments:
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- `path`: mandatory, see [File Searching Logic](@/documentation/templates/overview.md#file-searching-logic) for details
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- `sha_type`: optional, one of `256`, `384` or `512`, defaults to `384`
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- `base64`: optional, `true` or `false`, defaults to `true`. Whether to encode the hash as base64
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```jinja2
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{{/* get_file_hash(path="static/js/app.js", sha_type=256) */}}
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```
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The function can also output a base64-encoded hash value when its `base64`
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parameter is set to `true`. This can be used to implement [subresource
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integrity](https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity).
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```jinja2
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<script src="{{/* get_url(path="static/js/app.js") */}}"
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integrity="sha384-{{ get_file_hash(path="static/js/app.js", sha_type=384, base64=true) | safe }}"></script>
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```
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Do note that subresource integrity is typically used when using external scripts, which `get_file_hash` does not support.
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### `get_image_metadata`
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Gets metadata for an image. This supports common formats like JPEG, PNG, WebP, BMP, GIF as well as SVG.
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It can take the following arguments:
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- `path`: mandatory, see [File Searching Logic](@/documentation/templates/overview.md#file-searching-logic) for details
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- `allow_missing`: optional, `true` or `false`, defaults to `false`. Whether a missing file should raise an error or not.
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The method returns a map containing `width`, `height` and `format` (the lowercased value as string).
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```jinja2
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{% set meta = get_image_metadata(path="...") %}
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Our image (.{{meta.format}}) has format is {{ meta.width }}x{{ meta.height }}
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```
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### `load_data`
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Loads data from a file or URL. Supported file types include *toml*, *json*, *csv* and *bibtex* and only supports UTF-8 encoding.
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Any other file type will be loaded as plain text.
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The `path` argument specifies the path to the data file, according to the [File Searching Logic](@/documentation/templates/overview.md#file-searching-logic).
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```jinja2
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{% set data = load_data(path="content/blog/story/data.toml") %}
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```
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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`.
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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:
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```jinja2
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{% set data = load_data(path="https://en.wikipedia.org/wiki/Commune_of_Paris", required=false) %}
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{% if data %}{{ data | safe }}{% else %}No data found{% endif %}
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```
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The optional `format` argument allows you to specify and override which data type is contained
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within the file specified in the `path` argument. Valid entries are `toml`, `json`, `csv`, `bibtex`
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or `plain`. If the `format` argument isn't specified, then the path extension is used.
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```jinja2
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{% set data = load_data(path="content/blog/story/data.txt", format="json") %}
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```
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Use the `plain` format for when your file has a toml/json/csv extension but you want to load it as plain text.
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For *toml* and *json*, the data is loaded into a structure matching the original data file;
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however, for *csv* there is no native notion of such a structure. Instead, the data is separated
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into a data structure containing *headers* and *records*. See the example below to see
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how this works.
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In the template:
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```jinja2
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{% set data = load_data(path="content/blog/story/data.csv") %}
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```
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In the *content/blog/story/data.csv* file:
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```csv
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Number, Title
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1,Gutenberg
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2,Printing
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```
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The equivalent json value of the parsed data would be stored in the `data` variable in the
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template:
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```json
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{
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"headers": ["Number", "Title"],
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"records": [
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["1", "Gutenberg"],
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["2", "Printing"]
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],
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}
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```
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The `bibtex` format loads data into a structure matching the format used by the
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[nom-bibtex crate](https://crates.io/crates/nom-bibtex). The following is an example of data
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in bibtex format:
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```
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@preamble{"A bibtex preamble" # " this is."}
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@Comment{
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Here is a comment.
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}
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Another comment!
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@string(name = "Vincent Prouillet")
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@string(github = "https://github.com/getzola/zola")
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@misc {my_citation_key,
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author= name,
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title = "Zola",
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note = "github: " # github
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} }
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```
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The following is the json-equivalent format of the produced bibtex data structure:
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```json
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{
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"preambles": ["A bibtex preamble this is."],
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"comments": ["Here is a comment.", "Another comment!"],
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"variables": {
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"name": "Vincent Prouillet",
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"github": "https://github.com/getzola/zola"
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},
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"bibliographies": [
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{
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"entry_type": "misc",
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"citation_key": "my_citation_key",
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"tags": {
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"author": "Vincent Prouillet",
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"title": "Zola",
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"note": "github: https://github.com/getzola/zola"
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}
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}
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]
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}
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```
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Finally, the bibtex data can be accessed from the template as follows:
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```jinja2
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{% set tags = data.bibliographies[0].tags %}
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This was generated using {{ tags.title }}, authored by {{ tags.author }}.
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```
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#### Remote content
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Instead of using a file, you can load data from a remote URL. This can be done by specifying a `url` parameter
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to `load_data` rather than `path`.
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```jinja2
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{% set response = load_data(url="https://api.github.com/repos/getzola/zola") %}
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{{ response }}
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```
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By default, the response body will be returned with no parsing. This can be changed by using the `format` argument
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as below.
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```jinja2
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{% set response = load_data(url="https://api.github.com/repos/getzola/zola", format="json") %}
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{{ response }}
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```
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When no other parameters are specified the URL will always be retrieved using a HTTP GET request.
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Using the parameter `method`, since version 0.14.0, you can also choose to retrieve the URL using a POST request.
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When using `method="POST"` you can also use the parameters `body` and `content_type`.
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The parameter body is the actual contents sent in the POST request.
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The parameter `content_type` should be the mimetype of the body.
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This example will make a POST request to the kroki service to generate a SVG.
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```jinja2
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{% set postdata = load_data(url="https://kroki.io/blockdiag/svg", format="plain", method="POST" ,content_type="text/plain", body="blockdiag {
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'Doing POST' -> 'using load_data'
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'using load_data' -> 'can generate' -> 'block diagrams';
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'using load_data' -> is -> 'very easy!';
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'Doing POST' [color = 'greenyellow'];
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'block diagrams' [color = 'pink'];
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'very easy!' [color = 'orange'];
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}")%}
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{{postdata|safe}}
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```
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#### Data caching
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Data file loading and remote requests are cached in memory during the build, so multiple requests aren't made
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to the same endpoint.
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URLs are cached based on the URL, and data files are cached based on the file modified time.
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The format is also taken into account when caching, so a request will be sent twice if it's loaded with two
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different formats.
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### `trans`
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Gets the translation of the given `key`, for the `default_language` or the `lang`uage given
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```jinja2
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{{/* trans(key="title") */}}
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{{/* trans(key="title", lang="fr") */}}
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```
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### `resize_image`
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Resizes an image file.
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Please refer to [_Content / Image Processing_](@/documentation/content/image-processing/index.md) for complete documentation.
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