hugo/content/en/functions/go-template/range.md
Bjørn Erik Pedersen 9b0050e9aa Squashed 'docs/' content from commit 5c085a37b
git-subtree-dir: docs
git-subtree-split: 5c085a37b297bf12f59efeaae591418ec025c10d
2024-01-27 10:48:33 +01:00

199 lines
3.9 KiB
Markdown

---
title: range
description: Iterates over a non-empty collection, binds context (the dot) to successive elements, and executes the block.
categories: []
keywords: []
action:
aliases: []
related:
- functions/go-template/break
- functions/go-template/continue
- functions/go-template/else
- functions/go-template/end
returnType:
signatures: [range COLLECTION]
aliases: [/functions/range]
toc: true
---
{{% include "functions/go-template/_common/truthy-falsy.md" %}}
```go-html-template
{{ $s := slice "foo" "bar" "baz" }}
{{ range $s }}
{{ . }} → foo bar baz
{{ end }}
```
Use with the [`else`] statement:
```go-html-template
{{ $s := slice "foo" "bar" "baz" }}
{{ range $s }}
<p>{{ . }}</p>
{{ else }}
<p>The collection is empty</p>
{{ end }}
```
Within a range block:
- Use the [`continue`] statement to stop the innermost iteration and continue to the next iteration
- Use the [`break`] statement to stop the innermost iteration and bypass all remaining iterations
## Understanding context
At the top of a page template, the [context] (the dot) is a `Page` object. Within the `range` block, the context is bound to each successive element.
With this contrived example that uses the [`seq`] function to generate a slice of integers:
```go-html-template
{{ range seq 3 }}
{{ .Title }}
{{ end }}
```
Hugo will throw an error:
can't evaluate field Title in type int
The error occurs because we are trying to use the `.Title` method on an integer instead of a `Page` object. Within the `range` block, if we want to render the page title, we need to get the context passed into the template.
{{% note %}}
Use the `$` to get the context passed into the template.
{{% /note %}}
This template will render the page title three times:
```go-html-template
{{ range seq 3 }}
{{ $.Title }}
{{ end }}
```
{{% note %}}
Gaining a thorough understanding of context is critical for anyone writing template code.
{{% /note %}}
[`seq`]: functions/collections/seq/
[context]: /getting-started/glossary/#context
## Array or slice of scalars
This template code:
```go-html-template
{{ $s := slice "foo" "bar" "baz" }}
{{ range $s }}
<p>{{ . }}</p>
{{ end }}
```
Is rendered to:
```html
<p>foo</p>
<p>bar</p>
<p>baz</p>
```
This template code:
```go-html-template
{{ $s := slice "foo" "bar" "baz" }}
{{ range $v := $s }}
<p>{{ $v }}</p>
{{ end }}
```
Is rendered to:
```html
<p>foo</p>
<p>bar</p>
<p>baz</p>
```
This template code:
```go-html-template
{{ $s := slice "foo" "bar" "baz" }}
{{ range $k, $v := $s }}
<p>{{ $k }}: {{ $v }}</p>
{{ end }}
```
Is rendered to:
```html
<p>0: foo</p>
<p>1: bar</p>
<p>2: baz</p>
```
## Array or slice of maps
This template code:
```go-html-template
{{ $m := slice
(dict "name" "John" "age" 30)
(dict "name" "Will" "age" 28)
(dict "name" "Joey" "age" 24)
}}
{{ range $m }}
<p>{{ .name }} is {{ .age }}</p>
{{ end }}
```
Is rendered to:
```html
<p>John is 30</p>
<p>Will is 28</p>
<p>Joey is 24</p>
```
## Array or slice of pages
This template code:
```go-html-template
{{ range where site.RegularPages "Type" "articles" }}
<h2><a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a></h2>
{{ end }}
```
Is rendered to:
```html
<h2><a href="/articles/article-3/">Article 3</a></h2>
<h2><a href="/articles/article-2/">Article 2</a></h2>
<h2><a href="/articles/article-1/">Article 1</a></h2>
```
## Maps
This template code:
```go-html-template
{{ $m := dict "name" "John" "age" 30 }}
{{ range $k, $v := $m }}
<p>key = {{ $k }} value = {{ $v }}</p>
{{ end }}
```
Is rendered to:
```go-html-template
<p>key = age value = 30</p>
<p>key = name value = John</p>
```
Unlike ranging over an array or slice, Hugo sorts by key when ranging over a map.
{{% include "functions/go-template/_common/text-template.md" %}}
[`else`]: /functions/go-template/else
[`break`]: /functions/go-template/break
[`continue`]: /functions/go-template/continue