Twig Component Agent Skill

Symfony UX TwigComponent for reusable UI building blocks -- server-rendered components with PHP classes and Twig templates. Use when creating buttons, cards, alerts, badges, navbars, or any reusable UI element with props, blocks/slots, computed properties, or anonymous (template-only) components. Code triggers: AsTwigComponent, #[AsTwigComponent], ExposeInTemplate, PreMount, PostMount, <twig:Alert />, <twig:Button>, component(), computed properties, anonymous component, HTML syntax. Also trigger when the user asks "how to create a reusable component", "how to make a component library", "how to pass props to a component", "how to use slots/blocks in a component", "how to build a design system in Symfony", "what is the HTML syntax for components", "how to create a component without a PHP class". Do NOT trigger for components that re-render dynamically on user input (use live-component), for JS behavior (use stimulus), or for page navigation (use turbo).

9k tokens

context cost

the whole folder, loaded on every use

files

instructions only

copies elsewhere

how many repositories repackaged it

165

stars on the repo

on the repository, not the skill itself

Install

one command, takes just this skill from the repository

npx skills add https://github.com/smnandre/symfony-ux-skills --skill twig-component

The instruction itself

22 sections, as written by the author

TwigComponent

Reusable UI components with PHP classes + Twig templates. Think React/Vue components, but server-rendered with zero JavaScript.

Two flavors exist: class components (PHP class + Twig template) for components that need logic, services, or computed properties, and anonymous components (Twig-only, no PHP class) for simple presentational elements.

When to Use TwigComponent

Use TwigComponent when you need reusable markup with props but no server re-rendering after the initial render. If the component needs to react to user input (re-render via AJAX, data binding, actions), use LiveComponent instead.

Good candidates: buttons, alerts, cards, badges, icons, form widgets, layout sections, navigation items, table rows, modals (structure only).

Installation

composer require symfony/ux-twig-component

Class Component

A PHP class annotated with #[AsTwigComponent] paired with a Twig template.

// src/Twig/Components/Alert.php
namespace App\Twig\Components;

use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;

#[AsTwigComponent]
final class Alert
{
    public string $type = 'info';
    public string $message;
    public bool $dismissible = false;
}

{# templates/components/Alert.html.twig #}
<div class="alert alert-{{ type }}" {{ attributes }}>
    {{ message }}
    {% if dismissible %}
        <button type="button" class="close">&times;</button>
    {% endif %}
</div>

{# Usage #}
<twig:Alert type="success" message="Saved!" />
<twig:Alert type="danger" message="Error occurred" dismissible />

{# With block content instead of message prop #}
<twig:Alert type="warning">
    <strong>Warning:</strong> Check your input
</twig:Alert>

Anonymous Component (Twig Only)

No PHP class needed. Props are declared with {% props %} directly in the template. Use for simple presentational components with no logic.

{# templates/components/Button.html.twig #}
{% props variant = 'primary', size = 'md', disabled = false %}

<button
    class="btn btn-{{ variant }} btn-{{ size }}"
    {{ disabled ? 'disabled' }}
    {{ attributes }}
>
    {% block content %}{% endblock %}
</button>

<twig:Button variant="danger" size="lg">Delete</twig:Button>

Props

Public Properties (Class Components)

Public properties become props. Required props have no default value.

#[AsTwigComponent]
final class Card
{
    public string $title;           // Required
    public ?string $subtitle = null; // Optional
    public bool $shadow = true;      // Optional with default
}

mount() for Derived State

Use mount() to compute values from incoming props. The method runs once during component initialization.

#[AsTwigComponent]
final class UserCard
{
    public User $user;
    public string $displayName;

    public function mount(User $user): void
    {
        $this->user = $user;
        $this->displayName = $user->getFullName();
    }
}

<twig:UserCard :user="currentUser" />

Dynamic Props (Colon Prefix)

Prefix a prop with : to pass a Twig expression instead of a string literal.

{# Pass a variable #}
<twig:Alert :type="alertType" :message="flashMessage" />

{# Pass an expression #}
<twig:UserList :users="users|filter(u => u.active)" />

Blocks (Slots)

Blocks let parent templates inject content into specific areas of a component.

Default Block

Content between component tags goes to {% block content %}:

{# Component template #}
<div class="card">{% block content %}{% endblock %}</div>

{# Usage #}
<twig:Card><p>This is the card content</p></twig:Card>

Named Blocks

{# templates/components/Modal.html.twig #}
<dialog class="modal" {{ attributes }}>
    <header>{% block header %}Default Header{% endblock %}</header>
    <main>{% block content %}{% endblock %}</main>
    <footer>{% block footer %}{% endblock %}</footer>
</dialog>

<twig:Modal>
    <twig:block name="header"><h2>Confirm Action</h2></twig:block>
    <twig:block name="content"><p>Are you sure?</p></twig:block>
    <twig:block name="footer">
        <button>Cancel</button>
        <button>Confirm</button>
    </twig:block>
</twig:Modal>

Computed Properties

Methods prefixed with get become accessible as this.xxx in templates. They are computed on each access (not cached across re-renders -- for caching, see LiveComponent's computed).

#[AsTwigComponent]
final class ProductCard
{
    public Product $product;

    public function getFormattedPrice(): string
    {
        return number_format($this->product->getPrice(), 2) . ' EUR';
    }

    public function isOnSale(): bool
    {
        return $this->product->getDiscount() > 0;
    }
}

<div class="product">
    <span class="price">{{ this.formattedPrice }}</span>
    {% if this.onSale %}
        <span class="badge">Sale!</span>
    {% endif %}
</div>

Attributes

Extra HTML attributes passed to the component are available via {{ attributes }}. This is how you let consumers add custom classes, ids, data attributes, etc.

{# Usage #}
<twig:Alert type="info" message="Hello" class="my-class" id="main-alert" data-controller="alert" />

{# In component template -- renders class, id, data-controller #}
<div {{ attributes }}>...</div>

Attributes Methods

{# Merge with defaults #}
<div {{ attributes.defaults({class: 'alert'}) }}>

{# Exclude specific #}
<div {{ attributes.without('id', 'class') }}>

{# Only render specific #}
<div id="{{ attributes.render('id') }}">

{# Check existence #}
{% if attributes.has('disabled') %}

Components as Services

Components are Symfony services -- autowiring works naturally. Use the constructor for dependencies, public properties for props.

#[AsTwigComponent]
final class FeaturedProducts
{
    public function __construct(
        private readonly ProductRepository $products,
    ) {}

    public function getProducts(): array
    {
        return $this->products->findFeatured(limit: 6);
    }
}

{# templates/components/FeaturedProducts.html.twig #}
<div class="featured-products">
    {% for product in this.products %}
        <twig:ProductCard :product="product" />
    {% endfor %}
</div>

{# Usage -- no props needed, data comes from service #}
<twig:FeaturedProducts />

Lifecycle Hooks

use Symfony\UX\TwigComponent\Attribute\PreMount;
use Symfony\UX\TwigComponent\Attribute\PostMount;

#[AsTwigComponent]
final class DataTable
{
    public array $data;
    public string $sortBy = 'id';

    #[PreMount]
    public function preMount(array $data): array
    {
        // Modify/validate incoming data before property assignment
        $data['sortBy'] ??= 'id';
        return $data;
    }

    #[PostMount]
    public function postMount(): void
    {
        // Runs after all props are set
        $this->data = $this->sortData($this->data);
    }
}

Nested Components

Components compose naturally -- nest them like HTML elements:

<twig:Card>
    <twig:block name="header">
        <twig:Icon name="star" /> Featured
    </twig:block>
    <twig:block name="content">
        <twig:ProductList :products="featuredProducts">
            <twig:block name="empty">
                <twig:Alert type="info" message="No products found" />
            </twig:block>
        </twig:ProductList>
    </twig:block>
</twig:Card>

Configuration

# config/packages/twig_component.yaml
twig_component:
    anonymous_template_directory: 'components/'
    defaults:
        App\Twig\Components\: 'components/'

HTML vs Twig Syntax

{# HTML syntax (recommended -- better IDE support, more readable) #}
<twig:Alert type="success" message="Done!" />

{# Twig syntax (alternative -- useful in edge cases) #}
{% component 'Alert' with {type: 'success', message: 'Done!'} %}
{% endcomponent %}

Prefer HTML syntax (<twig:...>) in all cases. The Twig syntax ({% component %}) is legacy and less readable.

References

Full API (attribute options, hooks, configuration, all methods): references/api.md
Patterns (forms, tables, layouts, composition, real-world examples): references/patterns.md
Gotchas (attributes, naming, nested components, common pitfalls): references/gotchas.md

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