# Template Functions Reference

URL: /bengal/docs/0.5.1/reference/template-functions/
Section: template-functions
Tags: reference, templates, filters, kida, hugo

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Bengal provides powerful template filters for querying, filtering, and transforming content collections. Many filters are inspired by Hugo for easy migration. Info Important Implementation Maturity: Bengal currently ships with over 80+ native template functions and filters. While our documentation is being expanded to provide exhaustive examples for every edge case, the core implementation for Math, Strings, Collections, SEO, and Autodoc is fully production-ready and registered in the engine. Functions vs Filters: Understanding the Difference Bengal provides two types of template capabilities: functions and filters. Understanding when to use each helps you write clearer, more efficient templates. Filters: Transform Values Filters transform a value using the pipe operator (| or |>). The value on the left becomes the first argument to the filter. Syntax: {{ value | filter }} {{ value | filter(arg1, arg2) }} {{ value |> filter1 |> filter2 }} When to use: When you have a value to transform. Examples: {# Transform text #} {{ page.title | upper }} {{ page.content | markdown | safe }} {# Transform collections #} {{ site.pages | where('draft', false) | sort_by('date') }} {# Chain transformations #} {{ text |> slugify |> truncate(50) }} Registered in: env.filters (available via pipe operator) Functions: Standalone Operations Functions are called directly without a value to transform. They perform operations or retrieve data. Syntax: {{ function() }} {{ function(arg1, arg2) }} When to use: When performing an operation that doesn't transform an existing value. Examples: {# Retrieve data #} {{ get_page('docs/about') }} {{ get_data('data/authors.json') }} {# Generate references #} {{ ref('docs/getting-started') }} {{ get_section('blog') }} {# Check conditions #} {{ page_exists('path/to/page') }} Registered in: env.globals (available as direct function calls) Quick Decision Guide Use Case Type Example Transform text Filter {{ text \| upper }} Transform a collection Filter {{ pages \| where('draft', false) }} Chain transformations Filter {{ data \|> filter1 \|> filter2 }} Retrieve a page Function {{ get_page('path') }} Load data file Function {{ get_data('file.json') }} Generate cross-reference Function {{ ref('docs/page') }} Check if page exists Function {{ page_exists('path') }} Why This Matters Filters are designed for data transformation pipelines: Read left-to-right: data |> transform |> format |> output Chain multiple operations: pages |> filter |> sort |> limit Functional programming style Functions are designed for operations and lookups: No implicit left operand Direct calls: get_page('path') not | get_page('path') Procedural style Common Patterns Pattern 1: Filter a collection, then use a function {% let blog_posts = site.pages |> where('type', 'blog') |> sort_by('date', reverse=true) %} {% for post in blog_posts %} {# Use function to get related page #} {% let related = get_page(post.metadata.related) %} {% if related %} <a href="{{ related.url }}">Related: {{ related.title }}</a> {% end %} {% end %} Pattern 2: Function to get data, filter to transform {% let authors = get_data('data/authors.json') %} {% let active_authors = authors |> where('active', true) |> sort_by('name') %} Pattern 3: Function result used in filter chain {% let section = get_section('blog') %} {% let recent = section.pages |> sort_by('date', reverse=true) |> limit(5) %} Note Note Can't remember which is which? Ask: "Do I have a value to transform?" Yes → Use a filter (| or |>) No → Use a function (direct call) Topics Collection Filters Filter, sort, group, and transform collections of pages or items Navigation Functions Functions for navigating sections and checking page existence Linking Functions Generate links to pages, headings, and external documentation Internationalization Functions Translation, language detection, and localized formatting Template Functions Reference (Generated) Auto-generated index of all template filters and functions String & Date Filters Text transformation and date calculation filters Page & Section Properties Properties available on page and section objects Math & Data Functions Mathematical operations and data file manipulation Content Filters HTML and content manipulation filters View Filters Convert pages to normalized view objects for easier templating SEO, Image & Theme Functions SEO meta tags, image manipulation, icons, and theme features Debug Filters Development helpers for debugging templates

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Metadata:
- Author: lbliii
- Word Count: 651
- Reading Time: 3 minutes