Front-Office Development

Thelia 3 builds its front office on Twig templates and Symfony UX components. Components are reactive, and most of the UI logic stays on the server.

Technology stack

Technology	Purpose
Twig	Template engine
Symfony UX LiveComponents	Reactive UI components
Symfony UX TwigComponent	Static reusable components
Stimulus	JavaScript controllers
Webpack Encore	Asset management
DataAccessService	API data fetching

Architecture overview

Front-Office Request Flow
┌─────────────────────────────────────────────────────────────────┐
│                        Browser Request                          │
└─────────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────────┐
│                    Symfony Controller                           │
│              (renders Twig template)                            │
└─────────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────────┐
│                      Twig Template                              │
│    ┌─────────────────────────────────────────────────────┐      │
│    │  resources('/api/front/products')                   │      │
│    │  → DataAccessService → API Platform → Propel        │      │
│    └─────────────────────────────────────────────────────┘      │
│    ┌─────────────────────────────────────────────────────┐      │
│    │  {{ component('Flexy:ProductCard', {...}) }}        │      │
│    │  → LiveComponent (reactive)                         │      │
│    └─────────────────────────────────────────────────────┘      │
└─────────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────────┐
│                     HTML Response                               │
│              (with Stimulus controllers)                        │
└─────────────────────────────────────────────────────────────────┘

Key concepts

Data fetching with DataAccessService

Instead of running loops directly in templates, Thelia 3 uses DataAccessService to call API endpoints internally, without HTTP overhead:

{# Get current product ID from URL #}
{% set productId = attr('product', 'id') %}

{# Fetch product data via API #}
{% set product = resources('/api/front/products/' ~ productId) %}

{# Display product title #}
<h1>{{ product.i18ns.title }}</h1>

Reactive components with LiveComponents

LiveComponents give you reactive UI without writing JavaScript:

{# Render a reactive product component #}
{{ component('Flexy:Pages:Product', {product: product}) }}

The component automatically handles:

• Add to cart functionality
• Product variant selection
• Quantity updates
• Real-time price changes

JavaScript behavior with Stimulus

For custom JavaScript behavior, Stimulus controllers use a declarative approach:

<div data-controller="drawer">
    <button data-action="drawer#toggle">Open Menu</button>
    <div data-drawer-target="panel">...</div>
</div>

Theme structure

The front-office theme is a Symfony bundle (FlexyBundle). Its services are autoconfigured, and its TwigComponents/LiveComponents, Stimulus controllers and form theme all live inside the bundle, so there is no XML wiring to maintain.

The default Flexy theme shows the recommended structure:

templates/frontOffice/flexy/
├── base.html.twig              # Base layout
├── index.html.twig             # Homepage page template
├── category.html.twig          # Category page template
├── product.html.twig           # Product page template
├── checkout-*.html.twig        # Checkout page templates
├── account*.html.twig          # Customer account page templates
├── components/                 # Anonymous Twig components
│   ├── Atoms/                  # Smallest UI primitives (Icon, Font, ...)
│   ├── Molecules/              # Reusable UI elements
│   ├── Organisms/              # Complex components
│   ├── Layout/                 # Header, Footer, Hero, ...
│   └── Page/                   # Page-level building blocks
├── src/                        # PHP code (autoconfigured by FlexyBundle)
│   ├── Controller/             # Front-office controllers
│   ├── DTO/                    # Data Transfer Objects
│   ├── Event/                  # Front-office events
│   ├── EventListener/          # Event listeners (ViewListener)
│   ├── Form/                   # Symfony form types
│   ├── Service/                # Services (DeliveryService, FormService, ...)
│   ├── Twig/                   # Twig extensions (DataAccessExtension)
│   ├── UiComponents/           # Twig/Live components (.php + colocated .html.twig)
│   └── FlexyBundle.php         # Bundle class (loadExtension / prependExtension)
├── form/                       # Form theme (flexy_form_theme.html.twig + fields/)
├── assets/                     # JS, CSS, images
│   └── controllers/            # Stimulus controllers
├── config/                     # Bundle config (config/packages/*.yaml)
├── template.xml                # Theme manifest
└── webpack.config.js           # Webpack Encore build config

Components: anonymous vs. PHP-backed

components/ holds anonymous Twig components (Atoms/Molecules/Organisms/Layout/Page): pure .html.twig files with no PHP class. src/UiComponents/ holds PHP-backed TwigComponents and LiveComponents, where each one is a PHP class with a colocated .html.twig template in the same folder.

Section contents

Section	Description
Twig Basics	Twig templating in Thelia
Data Access	Fetching data with resources()
Flexy Theme	Default theme structure
LiveComponents	Creating reactive components
Stimulus	JavaScript controllers
Theme Hooks	Theme extension points for modules
Forms	Front-office forms

Quick example

A minimal category page that uses all of these concepts together:

{% extends 'base.html.twig' %}

{# Get category ID from URL parameters #}
{% set categoryId = attr('category', 'id') %}

{# Fetch category and products via API #}
{% set category = resources('/api/front/categories/' ~ categoryId) %}
{% set products = resources('/api/front/products', {
    'productCategories.category.id': categoryId,
    'visible': true,
    'itemsPerPage': 30
}) %}

{% block body %}
    <h1>{{ category.i18ns.title }}</h1>

    {# Use a LiveComponent for filtering #}
    {{ component('Flexy:CategoryFilters', {
        initialCategoryId: categoryId,
        initialPage: 1
    }) }}

    {# Or render products directly #}
    <div class="product-grid">
        {% for product in products %}
            {{ component('Flexy:ProductCard', {product: product}) }}
        {% endfor %}
    </div>
{% endblock %}

{% block stimulus_controller %}
    {{ stimulus_controller('drawer') }}
{% endblock %}

Comparison with the back office

Aspect	Front office	Back office
Template engine	Twig	Twig (default-twig bundle)
Data fetching	DataAccessService	Propel Repository classes
Components	LiveComponents	Twig and Live components
Hooks	Minimal use	Extensively used
JavaScript	Stimulus	Stimulus

Next steps

1. Twig Basics for the Twig templating fundamentals
2. Data Access for the resources() function
3. Flexy Theme for the default theme