Twig Coding Standards — Craft CMS 5

Coding conventions for Twig templates in Craft CMS 5 projects. These apply to all Twig code — atomic components, views, layouts, builders, partials.

Companion Skills — Always Load Together

When this skill triggers, also load:

• craft-site

  — Template architecture and component patterns. Required when creating or editing components, layouts, views, or builders.

• craft-content-modeling

  — Content architecture. Required when template code involves element queries, field access, or section decisions.

For Twig architecture patterns (atomic design, routing, builders), see the

craft-site

skill. For PHP coding standards, see

craft-php-guidelines

.

Documentation

• Twig in Craft: https://craftcms.com/docs/5.x/development/twig.html
• Template tags: https://craftcms.com/docs/5.x/reference/twig/tags.html
• Template functions: https://craftcms.com/docs/5.x/reference/twig/functions.html
• Twig 3 docs: https://twig.symfony.com/doc/3.x/

Use

WebFetch

on specific doc pages when something isn't covered here.

Variable Naming

Single-word, descriptive, lowercase preferred. When multi-word is needed, use camelCase.

{# Correct #}
{% set heading = entry.title %}
{% set image = entry.heroImage.one() %}
{% set items = navigation.links.all() %}
{% set element = props.get('url') ? 'a' : 'span' %}
{% set buttonText = entry.callToAction %}
{% set containerClass = 'max-w-3xl' %}

{# Wrong — abbreviations #}
{% set el = props.get('url') ? 'a' : 'span' %}
{% set btn = entry.callToAction %}
{% set nav = navigation.links.all() %}

{# Wrong — snake_case #}
{% set button_text = entry.callToAction %}
{% set container_class = 'max-w-3xl' %}

No abbreviations:

element

not

el

,

button

not

btn

,

navigation

not

nav

,

description

not

desc

.

Prefer single-word names when context makes the meaning clear (e.g.

heading

inside a component is better than

sectionHeading

). But multi-word camelCase is perfectly fine when needed for clarity.

Null Handling

??

is the default. Always safe, always portable.

???

(empty coalesce) is acceptable if the project already has

nystudio107/craft-empty-coalesce

or

nystudio107/craft-seomatic

installed — both provide the operator. But never install a plugin just for

???

. Check

composer.json

first.

{# Always correct #}
{% set heading = entry.heading ?? '' %}
{% set image = entry.heroImage.one() ?? null %}
{{ props.get('label') ?? 'Default' }}

{# OK if empty-coalesce or SEOmatic is installed — checks empty, not just null #}
{% set heading = entry.heading ??? '' %}

{# Wrong — verbose, unnecessary #}
{% if entry.heading is defined and entry.heading is not null %}
{% if entry.heading is not defined %}

Twig 3.21.x (Craft 5) does not have the nullsafe operator (

?.

). That requires Twig 3.23+. Use

??

and ternaries instead:

{# Can't do this yet #}
{{ entry?.author?.fullName }}

{# Do this instead #}
{{ entry.author.fullName ?? '' }}

Whitespace Control

Use

{%-

and

{{-

for whitespace trimming. Never use

{%- minify -%}

.

{# Correct — surgical whitespace control #}
{%- set heading = entry.title -%}
{%- if heading -%}
    {{- heading -}}
{%- endif -%}

{# Wrong — deprecated minification approach #}
{%- minify -%}
    {% set heading = entry.title %}
{%- endminify -%}

Apply whitespace control on tags that produce unwanted blank lines in output. Not every tag needs it — use where visible output whitespace matters.

Include Isolation

Every

{% include %}

MUST use

only

. No exceptions.

{# Correct — explicit, isolated #}
{%- include '_atoms/buttons/button--primary' with {
    text: entry.title,
    url: entry.url,
} only -%}

{# Wrong — ambient variables leak in #}
{%- include '_atoms/buttons/button--primary' with {
    text: entry.title,
    url: entry.url,
} -%}

Without

only

, a component can silently depend on variables from its parent scope, creating invisible coupling.

No Macros for Components

Never use

{% macro %}

for UI components. Macros don't support extends/block and their scoping model differs from includes.

{# Wrong — macro for a component #}
{% macro button(text, url) %}
    <a href="{{ url }}">{{ text }}</a>
{% endmacro %}

{# Correct — include with isolation #}
{%- include '_atoms/buttons/button--primary' with {
    text: text,
    url: url,
} only -%}

Macros are acceptable for utility functions that return strings (e.g., formatting helpers), not for rendering UI.

Comment Headers

Every component file gets a section header comment:

{# =========================================================================
   Component Name
   Brief description of what this component does.
   ========================================================================= #}

Props files, variant files, views, layouts — all get headers. The

=========

separator matches the PHP convention from

craft-php-guidelines

.

Craft Twig Helpers

{% tag %}

— Polymorphic Elements

Primary tool for rendering elements whose tag name depends on props.

{%- set element = props.get('url') ? 'a' : 'span' -%}

{%- tag element with {
    class: classes.implode(' '),
    href: props.get('url') ?? false,
    target: props.get('target') ?? false,
    rel: props.get('rel') ?? false,
    aria: {
        label: props.get('label') ?? false,
    },
} -%}
    {{ props.get('text') }}
{%- endtag -%}

Rules:

• Variable name must be descriptive:

  element

  ,

  heading

  ,

  wrapper

  . Never

  el

  ,

  hd

  .

• false

  omits an attribute entirely from the rendered HTML.

• null

  also omits. Use

  false

  when explicitly excluding,

  null

  when absent.

• class

  accepts arrays with automatic falsy filtering.

• aria

  and

  data

  accept nested hashes that expand to

  aria-*

  /

  data-*

  attributes.

tag()

— Inline Element Function

For simple elements without complex inner content:

{{ tag('span', { class: 'sr-only', text: '(opens in new window)' }) }}
{{ tag('img', { src: image.url, alt: image.title, loading: 'lazy' }) }}
{{ tag('i', { class: ['fa-solid', icon], aria: { hidden: 'true' } }) }}

• text:

  key = HTML-encoded content.

• html:

  key = raw HTML content (trusted input only).
• Self-closing elements (

  img

  ,

  input

  ,

  br

  ) handled automatically.

attr()

— Attribute Strings

For building attributes in non-tag contexts:

<div{{ attr({ class: ['card', active ? 'card--active'], data: { id: entry.id } }) }}>

Returns a space-prefixed attribute string. Same

false

-means-omit and class array filtering as

{% tag %}

.

|attr

Filter

For merging attributes onto existing HTML strings:

{{ svg('@webroot/icons/check.svg')|attr({ class: 'w-4 h-4', aria: { hidden: 'true' } }) }}

|parseAttr

Filter

For extracting attributes from an HTML string into a hash for manipulation:

{% set attributes = '<div class="foo" data-id="1">'|parseAttr %}
{# attributes = { class: 'foo', data: { id: '1' } } #}

|append

Filter

For adding content to an element string:

{{ svg('@webroot/icons/logo.svg')|append('<title>Company Logo</title>', 'replace') }}

svg()

Function

{{ svg('@webroot/icons/logo.svg') }}
{{ svg(entry.svgField.one()) }}

Combine with

|attr

for classes and aria attributes. Use

|append

for accessible labels inside the SVG.

collect()

Conventions

collect()

wraps a Twig hash into a Collection object. Primary use cases:

Props collection

{%- set props = collect({
    heading: heading ?? null,
    content: content ?? null,
    utilities: utilities ?? null,
}) -%}

{# Access with get() #}
{{ props.get('heading') }}
{{ props.get('size', 'text-base') }}

{# Merge additional props #}
{%- set props = props.merge({ icon: icon ?? null }) -%}

Class collection (named keys)

{%- set classes = collect({
    layout: 'flex items-center gap-2',
    color: 'bg-brand-primary text-white',
    hover: 'hover:bg-brand-accent',
    utilities: props.get('utilities'),
}) -%}

class="{{ classes.implode(' ') }}"

Null values in

collect()

produce harmless extra spaces when joined — browsers normalize whitespace in class attributes. Use

classes.filter(v => v).implode(' ')

if you want pristine output for devMode inspection, but plain

implode(' ')

is fine for production.

Entry queries as Collections

{# .collect instead of .all() when you need Collection methods #}
{%- set entries = craft.entries.section('blog').eagerly().collect -%}
{%- set featured = entries.filter(e => e.featured).first -%}

Common Pitfalls

1. ???

   operator without the plugin — requires

   nystudio107/craft-empty-coalesce

   or

   nystudio107/craft-seomatic

   . Check

   composer.json

   before using. Default to

   ??

   .
2. snake_case variables — use camelCase:

   heroImage

   not

   hero_image

   .
3. Missing

   only

   — silent variable leaking, invisible coupling.

4. {%- minify -%}

   — deprecated. Use

   {%-

   whitespace control.
5. Abbreviations —

   el

   ,

   btn

   ,

   nav

   ,

   desc

   ,

   ctr

   → spell it out.

6. is not defined

   — verbose null checking.

   ??

   handles it.
7. Macros as components — wrong scoping, no extends/block support.
8. Hardcoded colors in class strings —

   bg-yellow-600

   →

   bg-brand-accent

   .
9. String concatenation for classes —

   'flex ' ~ extraClass

   → use

   collect({})

   with named keys.

10. options.x

    pattern — old macro convention. Use direct variable names.