hugo/content/functions/intersect.md
Bjørn Erik Pedersen ba45da9d03 Squashed 'docs/' changes from 44fe0285..32356e4e
32356e4e Fix typo in header of shortcode-templates.md
c8f1a2d2 Correct code example for index template function
bfa6a55d Escape code fencing
ff8b2f99 Fix typos in deployment with wercker tutorial
557c36e8 theme: Merge commit '7fbb4bed25001182bfeb91f79db0f0c1936582ee'
7fbb4bed Squashed 'themes/gohugoioTheme/' changes from 7dd8a302..ca53082d
ce31cee0 Add "See Also" config
158cee1b Make the tags into keywords
61600be6 Add a note to the related section
49edb5a2 Relase 0.27.1
c9bbc001 releaser: Add release notes to /docs for release of 0.27.1
213c6c3b Add bugs poster
8b4590cd Add KeyCDN integration tutorial
2b277859 Add tutorial videos to several docs pages
950fef1f Update roadmap to link to the correct milestones page
496f5bf6 Rename relnotes
d6f9378d Bump Netlify versions to 0.27
087fde7f Update 0.27 release notes
603f94ae docs: Document Related Content
3790f6a3 releaser: Bump versions for release of 0.27
0948868c releaser: Add release notes to /docs for release of 0.27

git-subtree-dir: docs
git-subtree-split: 32356e4eabe357ae914f4d1d59e8ae31ce936723
2017-09-21 19:03:00 +02:00

56 lines
1.8 KiB
Markdown

---
title: intersect
linktitle: intersect
description: Returns the common elements of two arrays or slices.
godocref:
date: 2017-02-01
publishdate: 2017-02-01
lastmod: 2017-02-01
categories: [functions]
menu:
docs:
parent: "functions"
keywords: []
signature: ["intersect SET1 SET2"]
workson: []
hugoversion:
relatedfuncs: []
deprecated: false
aliases: []
---
The elements supported are strings, integers, and floats (only float64).
A useful example of `intersect` functionality is a "related posts" block. `isset` allows us to create a list of links to other posts that have tags that intersect with the tags in the current post.
The following is an example of a "related posts" [partial template][partials] that could be added to a [single page template][single]:
{{< code file="layouts/partials/related-posts.html" download="related-posts.html" >}}
<ul>
{{ $page_link := .Permalink }}
{{ $tags := .Params.tags }}
{{ range .Site.Pages }}
{{ $page := . }}
{{ $has_common_tags := intersect $tags .Params.tags | len | lt 0 }}
{{ if and $has_common_tags (ne $page_link $page.Permalink) }}
<li><a href="{{ $page.Permalink }}">{{ $page.Title }}</a></li>
{{ end }}
{{ end }}
</ul>
{{< /code >}}
This is also very useful to use as `AND` filters when combined with where:
```
{{ $pages := where .Site.RegularPages "Type" "not in" (slice "page" "about") }}
{{ $pages := $pages | union (where .Site.RegularPages "Params.pinned" true) }}
{{ $pages := $pages | intersect (where .Site.RegularPages "Params.images" "!=" nil) }}
```
The above fetches regular pages not of `page` or `about` type unless they are pinned. And finally, we exclude all pages with no `images` set in Page params.
See [union](/functions/union) for `OR`.
[partials]: /templates/partials/
[single]: /templates/single-page-templates/