mirror of
https://github.com/gohugoio/hugo.git
synced 2024-11-30 07:48:47 -05:00
60 lines
2 KiB
Markdown
60 lines
2 KiB
Markdown
|
---
|
||
|
|
title: len
|
||
|
|
linktitle: len
|
||
|
|
description: Returns the length of a variable according to its type.
|
||
|
|
godocref: https://golang.org/pkg/builtin/#len
|
||
|
|
date: 2017-02-01
|
||
|
|
publishdate: 2017-02-01
|
||
|
|
lastmod: 2017-04-18
|
||
|
|
categories: [functions]
|
||
|
|
#tags: []
|
||
|
|
signature: ["len INPUT"]
|
||
|
|
workson: [lists,taxonomies,terms]
|
||
|
|
hugoversion:
|
||
|
|
relatedfuncs: []
|
||
|
|
deprecated: false
|
||
|
|
toc: false
|
||
|
|
aliases: []
|
||
|
|
---
|
||
|
|
|
||
|
|
`len` is a built-in function in Golang that returns the length of a variable according to its type. From the Golang documentation:
|
||
|
|
|
||
|
|
> Array: the number of elements in v.
|
||
|
|
>
|
||
|
|
> Pointer to array: the number of elements in *v (even if v is nil).
|
||
|
|
>
|
||
|
|
> Slice, or map: the number of elements in v; if v is nil, len(v) is zero.
|
||
|
|
>
|
||
|
|
> String: the number of bytes in v.
|
||
|
|
>
|
||
|
|
> Channel: the number of elements queued (unread) in the channel buffer; if v is nil, len(v) is zero.
|
||
|
|
|
||
|
|
`len` is also considered a [fundamental function for Hugo templating][].
|
||
|
|
|
||
|
|
## `len` Example 1: Longer Headings
|
||
|
|
|
||
|
|
You may want to append a class to a heading according to the length of the string therein. The following templating checks to see if the title's length is greater than 80 characters and, if so, adds a `long-title` class to the `<h1>`:
|
||
|
|
|
||
|
|
{{< code file="check-title-length.html" >}}
|
||
|
|
<header>
|
||
|
|
<h1{{if gt (len .Title) 80}} class="long-title"{{end}}>{{.Title}}</h1>
|
||
|
|
</header>
|
||
|
|
{{< /code >}}
|
||
|
|
|
||
|
|
## `len` Example 2: Counting Pages with `where`
|
||
|
|
|
||
|
|
The following templating uses [`where`][] in conjunction with `len` to figure out the total number of content pages in a `posts` [section][]:
|
||
|
|
|
||
|
|
{{< code file="how-many-posts.html" >}}
|
||
|
|
{{ $posts := (where .Site.RegularPages "Section" "==" "post") }}
|
||
|
|
{{ $postCount := len $posts }}
|
||
|
|
{{< /code >}}
|
||
|
|
|
||
|
|
Note the use of `.RegularPages`, a [site variable][] that counts all regular content pages but not the `_index.md` pages used to add front matter and content to [list templates][].
|
||
|
|
|
||
|
|
|
||
|
|
[fundamental function for Hugo templating]: /templates/introduction/
|
||
|
|
[list templates]: /templates/lists/
|
||
|
|
[section]: /content-management/sections/
|
||
|
|
[site variable]: /variables/site/
|
||
|
|
[`where`]: /functions/where/
|