mirror of
https://github.com/gohugoio/hugo.git
synced 2024-12-29 01:44:07 +00:00
151 lines
7.1 KiB
Markdown
151 lines
7.1 KiB
Markdown
---
|
||
date: 2014-11-25
|
||
menu:
|
||
main:
|
||
parent: extras
|
||
next: /extras/livereload
|
||
prev: /extras/comments
|
||
title: Cross-References
|
||
toc: true
|
||
weight: 40
|
||
---
|
||
|
||
Hugo makes it easy to link documents together with the `ref` and `relref` shortcodes. These shortcodes are also used to safely provide links to headings inside of your content, whether across documents or within a document. The only difference between `ref` and `relref` is whether the resulting URL is absolute (`http://1.com/about/`) or relative (`/about/`).
|
||
|
||
## Using `ref` and `relref`
|
||
|
||
{{</* ref "document" */>}}
|
||
{{</* ref "#anchor" */>}}
|
||
{{</* ref "document#anchor" */>}}
|
||
{{</* relref "document" */>}}
|
||
{{</* relref "#anchor" */>}}
|
||
{{</* relref "document#anchor" */>}}
|
||
|
||
The single parameter to `ref` is a string with a content _document name_ (`about.md`), an in-document _anchor_ (`#who`), or both (`about.md#who`).
|
||
|
||
### Document Names
|
||
|
||
The _document name_ is the name of a document including the format extension; this may be just the filename, or the relative path from the `content/` directory. With a document `content/blog/post.md`, either format will produce the same result.
|
||
|
||
{{</* relref "blog/post.md" */>}} ⇒ `/blog/post/`
|
||
{{</* relref "post.md" */>}} ⇒ `/blog/post/`
|
||
|
||
If you have multiple sections with the same filename, you should only use the relative path format, because the behaviour is _undefined_. So, if I also have a document `link/post.md`, the output of `ref` is unknown for `post.md`.
|
||
|
||
{{</* relref "blog/post.md" */>}} ⇒ `/blog/post/`
|
||
{{</* relref "post.md" */>}} ⇒ `/blog/post/` (maybe)
|
||
{{</* relref "post.md" */>}} ⇒ `/link/post/` (maybe)
|
||
{{</* relref "link/post.md" */>}} ⇒ `/link/post/`
|
||
|
||
A relative document name must *not* begin with a slash (`/`).
|
||
|
||
{{</* relref "/blog/post.md" */>}} ⇒ `""`
|
||
|
||
### Anchors
|
||
|
||
When an _anchor_ is provided by itself, the current page’s unique identifier will be appended; when an _anchor_ is provided with a document name, the found page's unique identifier will be appended.
|
||
|
||
{{</* relref "#who" */>}} ⇒ `#who:9decaf7`
|
||
{{</* relref "blog/post.md#who" */>}} ⇒ `/blog/post/#who:badcafe`
|
||
|
||
More information about document unique identifiers and headings can be found [below]({{< ref "#hugo-heading-anchors" >}}).
|
||
|
||
### Examples
|
||
|
||
* `{{</* ref "blog/post.md" */>}}` ⇒ `http://1.com/blog/post/`
|
||
* `{{</* ref "post.md#tldr" */>}}` ⇒ `http://1.com/blog/post/#tldr:caffebad`
|
||
* `{{</* relref "post.md" */>}}` ⇒ `/blog/post/`
|
||
* `{{</* relref "blog/post.md#tldr" */>}}` ⇒ `/blog/post/#tldr:caffebad`
|
||
* `{{</* ref "#tldr" */>}}` ⇒ `#tldr:badcaffe`
|
||
* `{{</* relref "#tldr" */>}}` ⇒ `#tldr:badcaffe`
|
||
|
||
## Hugo Heading Anchors
|
||
|
||
When using Markdown document types, Hugo generates heading anchors automatically. The generated anchor for this section is `hugo-heading-anchors`. Because the heading anchors are generated automatically, Hugo takes some effort to ensure that heading anchors are unique both inside a document and across the entire site.
|
||
|
||
Ensuring heading uniqueness across the site is accomplished with a unique identifier for each document based on its path. Unless a document is renamed or moved between sections *in the filesystem*, the unique identifier for the document will not change: `blog/post.md` will always have a unique identifier of `81df004c333b392d34a49fd3a91ba720`.
|
||
|
||
`ref` and `relref` were added so you can make these reference links without having to know the document’s unique identifier. (The links in document tables of contents are automatically up-to-date with this value.)
|
||
|
||
{{</* relref "extras/crossreferences.md#hugo-heading-anchors" */>}}
|
||
/extras/crossreferences/#hugo-heading-anchors:77cd9ea530577debf4ce0f28c8dca242
|
||
|
||
> What follows is a deeper discussion of *why* and *how* Hugo generates heading anchors. It is not necessary to know this to use `ref` and `relref`, but it may be useful in understanding how some anchors may not match your expectations.
|
||
|
||
### How to Generate a Heading Anchor
|
||
|
||
Convert the text of the heading to lowercase.
|
||
|
||
Hugo: A Fast & Modern Static Web Engine
|
||
hugo: a fast & modern static web engine
|
||
|
||
Replace anything that isn't an ASCII letter (`a-z`) or number (`0-9`) with a dash (`-`).
|
||
|
||
hugo: a fast & modern static web engine
|
||
hugo--a-fast---modern-static-web-engine
|
||
|
||
Get rid of extra dashes.
|
||
|
||
hugo--a-fast---modern-static-web-engine
|
||
hugo-a-fast-modern-static-web-engine
|
||
|
||
You have just converting the text of a heading to a suitable anchor. If your document has unique heading text, all of the anchors will be unique, too.
|
||
|
||
#### Specifying Heading Anchors
|
||
|
||
You can also tell Hugo to use a particular heading anchor.
|
||
|
||
# Hugo: A Fast & Modern Static Web Engine {#hugo-main}
|
||
|
||
Hugo will use `hugo-main` as the heading anchor.
|
||
|
||
### What About Duplicate Heading Anchors?
|
||
|
||
The technique outlined above works well enough, but some documents have headings with identical text, like the [shortcodes](/extras/shortcodes/) page—there are three headings with the text "Example". You can specify heading anchors manually:
|
||
|
||
### Example {#example-1}
|
||
### Example {#example-2}
|
||
### Example {#example-3}
|
||
|
||
It’s easy to forget to do that all the time, and Hugo is smart enough to do it for you. It just adds `-x` to the end of each heading it has already seen.
|
||
|
||
* `### Example` ⇒ `example`
|
||
* `### Example` ⇒ `example-1`
|
||
* `### Example` ⇒ `example-2`
|
||
|
||
Sometimes it's a little harder, but Hugo can recover from those, too, by adding more suffixes:
|
||
|
||
* `# Heading` ⇒ `heading`
|
||
* `# Heading 1` ⇒ `heading-1`
|
||
* `# Heading` ⇒ `heading-1-1`
|
||
* `# Heading` ⇒ `heading-1-2`
|
||
* `# Heading 1` ⇒ `heading-2`
|
||
|
||
This can even affect specified heading anchors that come after a generated heading anchor.
|
||
|
||
* `# My Heading` ⇒ `my-heading`
|
||
* `# My Heading {#my-heading}` ⇒ `my-heading-1`
|
||
|
||
> This particular collision and override is unfortunate, but unavoidable because Hugo processes each heading for collision detection as it sees it during conversion.
|
||
|
||
This technique works well for documents rendered on individual pages, like blog posts. What about on Hugo list pages?
|
||
|
||
### Unique Heading Anchors in Lists
|
||
|
||
Hugo converts each document from Markdown independently. it doesn’t know that `blog/post.md` has an "Example" heading that will collide with the "Example" heading in `blog/post2.md`. Even if it did know this, the addition of `blog/post3.md` should not cause the anchors for the headings in the other blog posts to change.
|
||
|
||
Enter the document’s unique identifier. To prevent this sort of collision on
|
||
list pages, Hugo always appends the document's to a generated heading anchor.
|
||
So, the "Example" heading in `blog/post.md` actually turns into
|
||
`#example:81df004…`, and the "Example" heading in `blog/post2.md` actually
|
||
turns into `#example:8cf1599…`. All you have to know is the heading anchor that
|
||
was generated, not the document identifier; `ref` and `relref` take care of the
|
||
rest for you.
|
||
|
||
<a href='{{</* relref "blog/post.md#example" */>}}'>Post Example</a>
|
||
<a href='/blog/post.md#81df004…'>Post Example</a>
|
||
|
||
[Post Two Example]({{</* relref "blog/post2.md#example" */>}})
|
||
<a href='/blog/post2.md#8cf1599…'>Post Two Example</a>
|
||
|
||
Now you know.
|