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47 lines
1.5 KiB
Markdown
47 lines
1.5 KiB
Markdown
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---
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title: collections.Union
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description: Given two arrays or slices, returns a new array that contains the elements that belong to either or both arrays/slices.
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categories: []
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keywords: []
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action:
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aliases: [union]
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related:
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- functions/collections/Complement
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- functions/collections/Intersect
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- functions/collections/SymDiff
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- functions/collections/Union
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returnType: any
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signatures: [collections.Union SET1 SET2]
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aliases: [/functions/union]
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---
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Given two arrays (or slices) A and B, this function will return a new array that contains the elements or objects that belong to either A or to B or to both.
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```go-html-template
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{{ union (slice 1 2 3) (slice 3 4 5) }}
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<!-- returns [1 2 3 4 5] -->
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{{ union (slice 1 2 3) nil }}
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<!-- returns [1 2 3] -->
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{{ union nil (slice 1 2 3) }}
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<!-- returns [1 2 3] -->
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{{ union nil nil }}
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<!-- returns an error because both arrays/slices have to be of the same type -->
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```
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## OR filter in where query
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This is also very useful to use as `OR` filters when combined with where:
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```go-html-template
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{{ $pages := where .Site.RegularPages "Type" "not in" (slice "page" "about") }}
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{{ $pages = $pages | union (where .Site.RegularPages "Params.pinned" true) }}
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{{ $pages = $pages | intersect (where .Site.RegularPages "Params.images" "!=" nil) }}
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```
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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 parameters.
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See [intersect](/functions/collections/intersect) for `AND`.
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