Domain concept in Extbase

The domain layer is where you define the core logic and structure of your application — things like entities, value objects, repositories, and validators.

See https://en.wikipedia.org/wiki/Domain-driven_design for more in-depth information.

The Classes/Domain/ folder contains the domain logic of your Extbase extension. This is where you model real-world concepts in your application and define how they behave.

While Domain-Driven Design (DDD) suggests putting business-related services in the Domain layer, in most TYPO3 extensions you will actually see service classes placed in: Classes/Service/. It is also possible to put them in Classes/Domain/Service/.

Table of contents

Basic example of a model with a repository in Extbase

This example shows a basic model (representing a scientific paper in real life) and its corresponding repository.

packages/my_extension/Classes/Domain/Model/Paper.php

<?php

declare(strict_types=1);

namespace MyVendor\MyExtension\Domain\Model;

use TYPO3\CMS\Extbase\DomainObject\AbstractEntity;

class Paper extends AbstractEntity
{
    protected string $title = '';
    protected string $author = '';

    public function getTitle(): string
    {
        return $this->title;
    }

    public function setTitle(string $title): void
    {
        $this->title = $title;
    }

    public function getAuthor(): string
    {
        return $this->author;
    }

    public function setAuthor(string $author): void
    {
        $this->author = $author;
    }
}

Properties that will be persisted must be declared as protected or public.

To make properties available in Fluid templates, you must provide either a public property or a public getter method (starting with get, has, or is).

This repository follows Extbase's naming conventions and may stay empty unless custom queries are needed.

packages/my_extension/Classes/Domain/Repository/PaperRepository.php

<?php

declare(strict_types=1);

namespace MyVendor\MyExtension\Domain\Repository;

use MyVendor\MyExtension\Domain\Model\Paper;
use TYPO3\CMS\Extbase\Persistence\Repository;

/**
 * @extends Repository<Paper>
 */
class PaperRepository extends Repository {}

Extbase automatically detects which model the repository belongs to based on the naming convention <ModelName>Repository. No registration is necessary.

The PHPDoc @extends Repository<Paper> annotation helps static analysis tools (like PHPStan or Psalm) and IDEs with type inference and autocompletion.

By default a model is persisted to a database table with the following naming scheme: tx_[extension]_domain_model_[model].php. To create and define the database table use TCA configuration:

packages/my_extension/Configuration/TCA/tx_myextension_domain_model_paper.php

<?php

return [
    'ctrl' => [
        'title' => 'Paper',
        'label' => 'title',
        'delete' => 'deleted',
    ],
    'columns' => [
        'title' => [
            'label' => 'Title',
            'config' => [
                'type' => 'input',
                'eval' => 'trim,required',
            ],
        ],
        'author' => [
            'label' => 'Author',
            'config' => [
                'type' => 'input',
                'eval' => 'trim',
            ],
        ],
    ],
    'types' => [
        '0' => [
            'showitem' => 'title, author',
        ],
    ],
];

Subfolders of `Classes/Domain/`

Typical subfolders include:

Domain concept in Extbase

Basic example of a model with a repository in Extbase

Subfolders of Classes/Domain/

Model

Repository

Validator

Subfolders of `Classes/Domain/`