UFO Event Sourcing

A lightweight and modern Event Sourcing library for PHP 8.3+

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🚀 Features

• Stores domain events instead of the current state
• Rebuilds aggregate state through event replay
• Supports projections for building read models
• Provides interfaces for custom event stores and dispatchers

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📖 Core Concepts

• Resolver — module for generating differences between old and new state.
• Restorer — module for rebuilding an object from changes.
• Merger — service for step-by-step application of changes to an object.
• ContextDTO — DTO for passing context during change analysis (path, collection type, attributes).
• Attributes — PHP 8.3 attributes for controlling change detection behavior.

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🛠 Installation

composer require ufo-tech/event-sourcing

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📦 Components

Resolver

Class	Description
MainResolver	Delegates change detection to appropriate resolver
ObjectResolver	Handles objects via Reflection API
CollectionResolver	Supports associative arrays
ArrayResolver	Handles indexed arrays
ScalarResolver	Compares scalar values

Restorer & Merger

Class	Description
Merger	Merges changes into the base state
ObjectRestorer	Rebuilds an object from a collection of changes via DTOTransformer
ObjectDefinition	Defines the object type to restore from change history

Interfaces

Interface	Purpose
ResolverInterface	Detects changes between states
MergerInterface	Merges changes into a state
RestorerInterface	Restores an object from change history
MainResolverInterface	Encapsulates multiple resolvers
MainResolverFactoryInterface	Factory for creating the main resolver

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🟠 Attributes

Attribute	Purpose
#[ChangeIgnore]	Ignores a field during change detection
#[AsCollection]	Marks a field as a key-based collection

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🟢 Contexts

ContextDTO allows passing additional metadata during resolving:

• Current path (path)
• Type (collection/array/scalar)
• Special delete placeholder (__DELETED__)
• Supports nested paths for objects and collections

ContextDTO Rules

• ContextDTO::create() creates a base context with root path root.
• forPath(string $param) adds a path segment (e.g., root.products).
• makeAssocByPath(string $path) marks a path as associative (e.g., products, root.products.*).
• Supports pattern paths with $ that converts to * for nested collections.
• Delete placeholder can be customized via ContextDTO::create(deletePlaceholder: '__DELETED__').

Examples:

use Ufo\EventSourcing\Resolver\ContextDTO;

// Single path
$context = new ContextDTO(assocPaths: ['products']);
$context = new ContextDTO(assocPaths: 'products');

// Multiple paths
$context = new ContextDTO(assocPaths: ['products', 'items.subitems']);

// Custom delete placeholder
$context = new ContextDTO(deletePlaceholder: '__DELETED__', assocPaths: ['products']);

Using patterns:

// All subitems inside any items are treated as collections
$context = ContextDTO::create()
    ->makeAssocByPath('items.$.subitems');

// products.*.discounts.*.details are treated as associative
$context = ContextDTO::create()
    ->makeAssocByPath('products.$.discounts.$.details');

// Root-level collection
$context = ContextDTO::create(assocPaths: ['']);

📝 Note: $ automatically converts to * for wildcard path matching.

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📝 Usage Examples

Detecting Changes

$mainResolver = (new DefaultResolverFactory())->create();
$diff = $mainResolver->resolve($oldObject, $newObject);

Using context for associative collection

$context = ContextDTO::create()->makeAssocByPath('products');
$diff = $mainResolver->resolve($old, $new, $context);

Restoring an object from change history

$restorer = new ObjectRestorer(new Merger());
$restored = $restorer->restore(
    (new ObjectDefinition(MyDto::class))
        ->addChanges($firstChange)
        ->addChanges($secondChange)
);

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📚 Use Cases

• Event Sourcing and CQRS architectures
• Domain-Driven Design (DDD) based projects
• Service-oriented systems with event-based persistence

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📖 Documentation

Full documentation available at docs.ufo-tech.space

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📜 License

MIT © UFO Tech