mirror of
https://github.com/gohugoio/hugo.git
synced 2024-11-14 20:37:55 -05:00
41bc6f702a
2c0125b52 Remove .Site.Author 2cf8841b3 Update partialCached.md (#1924) 385487191 Update data-templates.md (#1926) ce207e141 Remove redundant markdown and fix a few typos (#1936) 3687c2953 Make heading id linkable, take 2 45c79bea7 Make heading id linkable b22079344 Delete duplicates the lines 557-569 and 570-582. (#1934) 0a90dc122 Rework the taxonomy variables page (#1935) 7f8979c50 Update theme 26e682a3a Update multilingual.md d40e7693f Update postcss.md 375d75c01 Update postcss npm instructions (#1931) 63020094a Emphasize Window shell selection (#1930) 56824be2c Update configuration.md b7b8f16b3 Docu 'Theme components': minor fix (#1929) 09dc81a05 Remove Docker from BSD page (#1927) 205fea204 netlify: Hugo 0.108.0 6abe49c28 Merge commit 'da670c38ee63a7fef25e2b9f42519232055b60dc' 12b59a4c5 docs: Add basic doc for wrapStandAloneImageWithinParagraph etc. ba07bd970 dartsass: Add sourceMapIncludeSources option git-subtree-dir: docs git-subtree-split: 2c0125b5290494d49334606c451446ebd9df3c21
118 lines
4.2 KiB
Markdown
118 lines
4.2 KiB
Markdown
---
|
||
title: apply
|
||
description: Given a map, array, or slice, `apply` returns a new slice with a function applied over it.
|
||
date: 2017-02-01
|
||
publishdate: 2017-02-01
|
||
lastmod: 2017-02-01
|
||
categories: [functions]
|
||
menu:
|
||
docs:
|
||
parent: "functions"
|
||
keywords: [advanced]
|
||
signature: ["apply COLLECTION FUNCTION [PARAM...]"]
|
||
workson: []
|
||
hugoversion:
|
||
relatedfuncs: []
|
||
deprecated: false
|
||
draft: false
|
||
aliases: []
|
||
---
|
||
|
||
{{< todo >}}
|
||
POTENTIAL NEW CONTENT: see apply/sequence discussion: https://discourse.gohugo.io/t/apply-printf-on-a-sequence/5722;
|
||
{{< /todo >}}
|
||
|
||
`apply` expects at least three parameters, depending on the function being applied.
|
||
|
||
1. The first parameter is the sequence to operate on.
|
||
2. The second parameter is the name of the function as a string, which must be the name of a valid [Hugo function][functions].
|
||
3. After that, the parameters to the applied function are provided, with the string `"."` standing in for each element of the sequence the function is to be applied against.
|
||
|
||
Here is an example of a content file with `names:` as a front matter field:
|
||
|
||
```
|
||
+++
|
||
names: [ "Derek Perkins", "Joe Bergevin", "Tanner Linsley" ]
|
||
+++
|
||
```
|
||
|
||
You can then use `apply` as follows:
|
||
|
||
```
|
||
{{ apply .Params.names "urlize" "." }}
|
||
```
|
||
|
||
Which will result in the following:
|
||
|
||
```
|
||
"derek-perkins", "joe-bergevin", "tanner-linsley"
|
||
```
|
||
|
||
This is *roughly* equivalent to using the following with [range]:
|
||
|
||
```
|
||
{{ range .Params.names }}{{ . | urlize }}{{ end }}
|
||
```
|
||
|
||
However, it is not possible to provide the output of a range to the [`delimit` function][delimit], so you need to `apply` it.
|
||
|
||
If you have `post-tag-list.html` and `post-tag-link.html` as [partials], you *could* use the following snippets, respectively:
|
||
|
||
{{< code file="layouts/partials/post-tag-list.html" copy="false" >}}
|
||
{{ with .Params.tags }}
|
||
<div class="tags-list">
|
||
Tags:
|
||
{{ $len := len . }}
|
||
{{ if eq $len 1 }}
|
||
{{ partial "post-tag-link.html" (index . 0) }}
|
||
{{ else }}
|
||
{{ $last := sub $len 1 }}
|
||
{{ range first $last . }}
|
||
{{ partial "post-tag-link.html" . }},
|
||
{{ end }}
|
||
{{ partial "post-tag-link.html" (index . $last) }}
|
||
{{ end }}
|
||
</div>
|
||
{{ end }}
|
||
{{< /code >}}
|
||
|
||
{{< code file="layouts/partials/post-tag-link.html" copy="false" >}}
|
||
<a class="post-tag post-tag-{{ . | urlize }}" href="/tags/{{ . | urlize }}">{{ . }}</a>
|
||
{{< /code >}}
|
||
|
||
This works, but the complexity of `post-tag-list.html` is fairly high. The Hugo template needs to perform special behavior for the case where there’s only one tag, and it has to treat the last tag as special. Additionally, the tag list will be rendered something like `Tags: tag1 , tag2 , tag3` because of the way that the HTML is generated and then interpreted by a browser.
|
||
|
||
This first version of `layouts/partials/post-tag-list.html` separates all of the operations for ease of reading. The combined and DRYer version is shown next:
|
||
|
||
```
|
||
{{ with .Params.tags }}
|
||
<div class="tags-list">
|
||
Tags:
|
||
{{ $sort := sort . }}
|
||
{{ $links := apply $sort "partial" "post-tag-link.html" "." }}
|
||
{{ $clean := apply $links "chomp" "." }}
|
||
{{ delimit $clean ", " }}
|
||
</div>
|
||
{{ end }}
|
||
```
|
||
|
||
Now in the completed version, you can sort the tags, convert the tags to links with `layouts/partials/post-tag-link.html`, [chomp] off stray newlines, and join the tags together in a delimited list for presentation. Here is an even DRYer version of the preceding example:
|
||
|
||
{{< code file="layouts/partials/post-tag-list.html" download="post-tag-list.html" >}}
|
||
{{ with .Params.tags }}
|
||
<div class="tags-list">
|
||
Tags:
|
||
{{ delimit (apply (apply (sort .) "partial" "post-tag-link.html" ".") "chomp" ".") ", " }}
|
||
</div>
|
||
{{ end }}
|
||
{{< /code >}}
|
||
|
||
{{% note %}}
|
||
`apply` does not work when receiving the sequence as an argument through a pipeline.
|
||
{{% /note %}}
|
||
|
||
[chomp]: /functions/chomp/ "See documentation for the chomp function"
|
||
[delimit]: /functions/delimit/ "See documentation for the delimit function"
|
||
[functions]: /functions/ "See the full list of Hugo functions to see what can be passed as an argument to the apply function."
|
||
[partials]: /templates/partials/
|
||
[range]: /functions/range/ "Learn the importance of the range function, a fundamental keyword in both Hugo templates and the Go programming language."
|