github.com/lyeb/hugo@v0.47.1/docs/content/en/functions/intersect.md (about)

     1  ---
     2  title: intersect
     3  linktitle: intersect
     4  description: Returns the common elements of two arrays or slices.
     5  godocref:
     6  date: 2017-02-01
     7  publishdate: 2017-02-01
     8  lastmod: 2017-02-01
     9  categories: [functions]
    10  menu:
    11    docs:
    12      parent: "functions"
    13  keywords: []
    14  signature: ["intersect SET1 SET2"]
    15  workson: []
    16  hugoversion:
    17  relatedfuncs: []
    18  deprecated: false
    19  aliases: []
    20  ---
    21  
    22  The elements supported are strings, integers, and floats (only float64).
    23  
    24  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.
    25  
    26  The following is an example of a "related posts" [partial template][partials] that could be added to a [single page template][single]:
    27  
    28  {{< code file="layouts/partials/related-posts.html" download="related-posts.html" >}}
    29  <ul>
    30  {{ $page_link := .Permalink }}
    31  {{ $tags := .Params.tags }}
    32  {{ range .Site.Pages }}
    33      {{ $page := . }}
    34      {{ $has_common_tags := intersect $tags .Params.tags | len | lt 0 }}
    35      {{ if and $has_common_tags (ne $page_link $page.Permalink) }}
    36          <li><a href="{{ $page.Permalink }}">{{ $page.Title }}</a></li>
    37      {{ end }}
    38  {{ end }}
    39  </ul>
    40  {{< /code >}}
    41  
    42  This is also very useful to use as `AND` filters when combined with where:
    43  
    44  ```
    45  {{ $pages := where .Site.RegularPages "Type" "not in" (slice "page" "about") }}
    46  {{ $pages := $pages | union (where .Site.RegularPages "Params.pinned" true) }}
    47  {{ $pages := $pages | intersect (where .Site.RegularPages "Params.images" "!=" nil) }}
    48  ```
    49  
    50  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.
    51  
    52  See [union](/functions/union) for `OR`.
    53  
    54  
    55  [partials]: /templates/partials/
    56  [single]: /templates/single-page-templates/