Template Functions

Gozzi provides extensive template functions beyond Go's built-ins for content manipulation, string operations, dates, collections, and more.

Content Functions

get_section

Get section data by name:

<!-- Get blog section -->
{{ $blog := get_section "blog" }}

<!-- Show recent posts -->
<h2>Recent Posts</h2>
{{ range first 5 (reverse $blog.Children) }}
  <a href="{{ .Permalink }}">{{ .Config.title }}</a>
{{ end }}

markdown

Render markdown inline:

{{ $markdown := "**Bold text** and _italic_" }}
{{ markdown $markdown }}
<!-- Output: <strong>Bold text</strong> and <em>italic</em> -->

load

Load external files:

<!-- Load SVG icon -->
{{ $svg := load "static/icon/arrow.svg" }}
{{ $svg }}

<!-- Load CSS inline -->
{{ $styles := load "static/css/critical.css" }}
<style>{{ $styles }}</style>

load_attribute

Load file as HTML attribute:

{{ $icon := load_attribute "static/icon/menu.svg" }}
<div data-icon="{{ $icon }}">Menu</div>

String Functions

urlize

Convert string to URL-safe slug:

{{ $slug := "My Great Post Title" | urlize }}
<!-- Output: my-great-post-title -->

<a href="/tags/{{ . | urlize }}">{{ . }}</a>

upper / lower

Change case:

{{ "hello world" | upper }}  <!-- HELLO WORLD -->
{{ "HELLO WORLD" | lower }}  <!-- hello world -->

trim

Remove whitespace:

{{ "  trim me  " | trim }}   <!-- trim me -->

split

Split string by delimiter:

{{ "one,two,three" | split "," }}
<!-- Output: ["one", "two", "three"] -->

{{ range split "a,b,c" "," }}
  <span>{{ . }}</span>
{{ end }}

contains

Check if string contains substring:

{{ if contains .Page.Config.tags "go" }}
  <span class="go-post">Go Related</span>
{{ end }}

has_prefix / has_suffix

Check string start/end:

{{ if has_prefix .Page.URL "/blog/" }}
  <nav>Blog Navigation</nav>
{{ end }}

{{ if has_suffix .Page.URL ".html" }}
  <!-- HTML page -->
{{ end }}

replace

Replace substring:

{{ replace "hello world" "world" "gozzi" }}
<!-- Output: hello gozzi -->

printf

Format strings:

{{ $author := "John Doe" }}
{{ $title := "My Post" }}
{{ printf "%s by %s" $title $author }}
<!-- Output: My Post by John Doe -->

{{ $url := printf "/tags/%s" (. | urlize) }}
<a href="{{ $url }}">{{ . }}</a>

Date Functions

date

Format dates:

<!-- Various formats -->
{{ date .Page.Config.date "January 2, 2006" }}
<!-- Output: January 15, 2025 -->

{{ date .Page.Config.date "2006-01-02" }}
<!-- Output: 2025-01-15 -->

{{ date .Page.Config.date "Jan 2" }}
<!-- Output: Jan 15 -->

{{ date .Page.Config.date "Monday, Jan 2, 2006" }}
<!-- Output: Wednesday, Jan 15, 2025 -->

now

Get current time:

{{ $now := now }}
{{ date $now "2006-01-02 15:04:05" }}
<!-- Output: 2025-01-15 14:30:45 -->

<!-- Copyright with current year -->
<p>© {{ date now "2006" }} My Site</p>

to_date

Parse date strings:

{{ $parsed := to_date "2025-01-15" }}
{{ date $parsed "January 2, 2006" }}
<!-- Output: January 15, 2025 -->

Collection Functions

limit

Limit number of items:

<!-- Show first 10 posts -->
{{ $posts := limit 10 .Section.Children }}
{{ range $posts }}
  <article>{{ .Config.title }}</article>
{{ end }}

first / last

Get first/last N items:

<!-- Latest 3 posts -->
{{ $latest := first 3 (reverse .Section.Children) }}
{{ range $latest }}
  <div>{{ .Config.title }}</div>
{{ end }}

<!-- Oldest 3 posts -->
{{ $oldest := last 3 .Section.Children }}

reverse

Reverse array order:

<!-- Newest first -->
{{ range reverse .Section.Children }}
  <article>{{ .Config.title }}</article>
{{ end }}

where

Filter collection:

<!-- Only published posts -->
{{ $published := where .Section.Children "Config.draft" false }}

<!-- Only featured posts -->
{{ $featured := where .Section.Children "Config.featured" true }}
{{ range $featured }}
  <div class="featured">{{ .Config.title }}</div>
{{ end }}

group_by

Group items by field:

<!-- Group posts by tags -->
{{ $groups := group_by .Section.Children "Config.tags" }}
{{ range $groups }}
  <h3>Tag: {{ .Key }}</h3>
  {{ range .Items }}
    <p>{{ .Config.title }}</p>
  {{ end }}
{{ end }}

sort

Sort collection:

<!-- Sort by date descending -->
{{ range sort .Section.Children ".Config.date" "desc" }}
  <article>{{ .Config.title }}</article>
{{ end }}

<!-- Sort by title ascending -->
{{ range sort .Section.Children ".Config.title" "asc" }}
  <li>{{ .Config.title }}</li>
{{ end }}

len

Get length:

<p>{{ len .Section.Children }} posts</p>
<p>{{ len .Page.Config.tags }} tags</p>

{{ if gt (len .Section.Children) 10 }}
  <!-- Show pagination -->
{{ end }}

Logic Functions

and / or / not

Boolean logic:

<!-- AND condition -->
{{ if and .Page.Config.featured (eq .Page.Config.draft false) }}
  <span class="featured-published">Featured & Published</span>
{{ end }}

<!-- OR condition -->
{{ if or (eq .Section.Name "blog") (eq .Section.Name "notes") }}
  <div class="content-section">Content</div>
{{ end }}

<!-- NOT condition -->
{{ if not .Page.Config.draft }}
  <div>Published content</div>
{{ end }}

eq / ne / lt / le / gt / ge

Comparisons:

<!-- Equal -->
{{ if eq .Section.Name "blog" }}
  <div>Blog section</div>
{{ end }}

<!-- Not equal -->
{{ if ne .Page.Config.template "home.html" }}
  <nav>Secondary Navigation</nav>
{{ end }}

<!-- Greater than -->
{{ if gt .Page.WordCount 1000 }}
  <span class="long-read">Long read</span>
{{ end }}

<!-- Less than or equal -->
{{ if le (len .Page.Config.tags) 3 }}
  <!-- Few tags -->
{{ end }}

default

Provide default value:

{{ $author := default "Anonymous" .Page.Config.extra.author }}
<p>By {{ $author }}</p>

{{ $description := default "No description" .Page.Config.description }}
<meta name="description" content="{{ $description }}">

with

Check existence and assign:

{{ with .Page.Config.description }}
  <p>{{ . }}</p>
{{ else }}
  <p>No description available</p>
{{ end }}

{{ with .Page.Config.extra.author }}
  <span class="author">By {{ . }}</span>
{{ end }}

Asset Functions

asset

Generate asset path with cache busting:

{{ asset "/css/main.css" . }}
<!-- Output: /css/main.css?v=abc123 -->

{{ asset "/js/app.js" . }}
<!-- Output: /js/app.js?v=def456 -->

<link rel="stylesheet" href="{{ asset "/css/main.css" . }}">
<script src="{{ asset "/js/app.js" . }}"></script>

Math Functions

Arithmetic

<!-- Addition -->
{{ add 5 3 }}  <!-- 8 -->

<!-- Subtraction -->
{{ sub 10 3 }}  <!-- 7 -->

<!-- Multiplication -->
{{ mul 4 5 }}  <!-- 20 -->

<!-- Division -->
{{ div 15 3 }}  <!-- 5 -->

<!-- Modulo -->
{{ mod 10 3 }}  <!-- 1 -->

Use Cases

<!-- Calculate percentage -->
{{ $total := len .Section.Children }}
{{ $featured := len (where .Section.Children "Config.featured" true) }}
{{ $percent := div (mul $featured 100) $total }}
<p>{{ $percent }}% of posts are featured</p>

<!-- Pagination math -->
{{ $totalPages := div (len .Section.Children) 10 }}
<p>Page 1 of {{ $totalPages }}</p>

Utility Functions

dict

Create dictionary:

<!-- Pass data to partial -->
{{ template "partials/_pagination.html" (dict "items" .Section.Children "per_page" 10 "current" 1) }}

<!-- Inside partial -->
<p>Showing {{ .per_page }} items per page</p>

slice

Create array:

{{ $colors := slice "red" "blue" "green" }}
{{ range $colors }}
  <span style="color: {{ . }}">{{ . }}</span>
{{ end }}

index

Access array/dict element:

{{ $tags := .Page.Config.tags }}
{{ index $tags 0 }}  <!-- First tag -->
{{ index $tags 1 }}  <!-- Second tag -->

{{ $data := dict "name" "John" "age" 30 }}
{{ index $data "name" }}  <!-- John -->

Pipeline and Chaining

Combine functions with pipes:

<!-- Chain string operations -->
{{ "  My Title  " | trim | upper | urlize }}
<!-- Output: my-title -->

<!-- Chain collection operations -->
{{ $recent := .Section.Children | reverse | first 5 }}
{{ range $recent }}
  <article>{{ .Config.title }}</article>
{{ end }}

<!-- Complex pipeline -->
{{ range .Section.Children | where "Config.featured" true | reverse | first 3 }}
  <div class="featured">{{ .Config.title }}</div>
{{ end }}

Custom Function Patterns

Reusable Variables

<!-- Define reusable filtered collections -->
{{ $published := where .Section.Children "Config.draft" false }}
{{ $featured := where $published "Config.featured" true }}
{{ $recent := first 5 (reverse $published) }}

<section class="featured">
  {{ range $featured }}
    <article>{{ .Config.title }}</article>
  {{ end }}
</section>

<section class="recent">
  {{ range $recent }}
    <article>{{ .Config.title }}</article>
  {{ end }}
</section>

Conditional Rendering

<!-- Show different content based on data -->
{{ $posts := .Section.Children }}
{{ if gt (len $posts) 0 }}
  <div class="posts-list">
    {{ range $posts }}
      <article>{{ .Config.title }}</article>
    {{ end }}
  </div>
{{ else }}
  <p>No posts yet. Check back soon!</p>
{{ end }}

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Related:

• Template Variables
• Template Functions Reference
• Advanced Patterns