Introduction

Simple Data Objects is a lightweight PHP 8.4+ library for creating typed Data Transfer Objects (DTOs) using constructor property promotion and PHP attributes.

Why Simple Data Objects?

DTOs are ubiquitous in modern PHP applications — they carry data between layers, validate input from HTTP requests, and serialize to/from APIs. Yet most implementations involve a lot of repetitive plumbing code.

Simple Data Objects removes that plumbing:

use StdOut\SimpleDataObjects\BaseData;
use StdOut\SimpleDataObjects\Attributes\Rules;
use StdOut\SimpleDataObjects\Attributes\Cast;
use StdOut\SimpleDataObjects\Casts\DateTimeCast;

class CreateOrderData extends BaseData
{
    public function __construct(
        #[Rules(['required', 'string', 'max:200'])]
        public readonly string $title,

        #[Rules(['required', 'email'])]
        public readonly string $customerEmail,

        #[Cast(new DateTimeCast('Y-m-d'))]
        public readonly DateTime $deliveryDate,

        public readonly ?string $notes = null,
    ) {}
}

// Validate + hydrate in one step
$order = CreateOrderData::fromValidated($request->all());

$order->title;           // 'New laptop'
$order->deliveryDate;    // DateTime object
$order->toArray();       // ['title' => ..., 'customerEmail' => ..., 'deliveryDate' => '2025-01-15', ...]
$order->toJson();        // JSON string

Core Concepts

Hydration

from() is a universal factory: it accepts arrays, Eloquent models and any Arrayable, stdClass, JsonSerializable, any Traversable, JSON strings, and plain objects. Nested DTOs, enums, and collections are resolved automatically.

Serialization

toArray() and toJson() serialize the object back to its wire format. Casts apply in both directions — hydration reads them, serialization writes them.

Attributes

All behaviour is declared on the constructor parameters:

• #[Cast(...)] — type conversion for dates, booleans, JSON, encryption, …
• #[Rules([...])] — Laravel validation rules
• #[Hidden] — exclude from toArray() output
• #[IgnoreIfNull] — omit null fields from output
• #[Flatten] — inline nested DTO fields into the parent array
• #[MapPropertyName] / #[TransformKeys] — key remapping

Performance

Reflection runs once per class per process, results are cached in memory. Enable file-based cache with MetadataRegistry::setStoragePath() to have opcache pre-compile all metadata across requests.

Requirements

Dependency	Version
PHP	^8.4
illuminate/contracts	^10 | ^11 | ^12 | ^13
illuminate/support	^10 | ^11 | ^12 | ^13
illuminate/validation	^10 | ^11 | ^12 | ^13

Works standalone — no Laravel application required. Validation uses the library's own minimal validator bootstrap when no container is available.