tonicforhealth/model-transformer

Simple abstraction for object transformations

v1.0.1 2017-05-18 08:45 UTC

Requires (Dev)

• phpspec/phpspec: ~2.3

MIT

• Dmytro Krasun

README

Simple abstraction for object transformations.

Installation

Require dependencies via composer:

$ composer require tonicforhealth/model-transformer

Usage

Possible use cases:

1. Separate domain model layer from view or presentation layer, but still keep objects.
2. Separate domain model from resource representations (in RESTful applications).

Suppose, there are two domain objects:

<?php 

class Product 
{
    /**
     * @var string
     */ 
    private $name; 
    
    /**
     * @var Category
     */
    private $category;
    
    // ... 
    
    /**
     * @return string
     */
    public function getName()
    {
        return $this->name;
    }
    
    /**
     * @return Category
     */
    public function getCategory()
    {
        return $this->category;
    }
}

class Category 
{
    /**
     * @var string
     */ 
    private $name; 
    
    // ... 
    
    /**
     * @return string
     */
    public function getName()
    {
        return $this->name;
    }
}

And one presentation object which can be used in presentation layer:

<?php 

class ProductPresentation
{
    /**
     * @var string
     */ 
    private $name;
     
    /**
     * @var string
     */
    private $categoryName;
    
    /**
     * @var int
     */
    private $purchasedCount;
    
    // ... 
    
    /**
     * @return string
     */
    public function getName()
    {
        return $this->name;
    }
    
    /**
     * @return string
     */
    public function getCategoryName()
    {
        return $this->categoryName;
    }
    
    /**
     * @return string
     */
    public function getPurchasedCount()
    {
        return $this->purchased;
    }    
}

There are lot of solutions for transforming Product and Category objects to ProductRepresentation:

• just create ProductRepresentation based Product and Category on at the needed place;
• create factory for ProductRepresentation;
• and so on.

This library provides simple and concise solution for this problem:

1. Create transformer for objects.
2. Register it in transformer manager or use it separately.

Possible transformer for ProductRepresentation:

<?php

class ProductToProductRepresentationModelTransformer implements ModelTransformerInterface
{
	/**
	 * @var ProductRepository
	 */
	private $productRepository;

	// ...

    /**
     * {@inheritdoc}
     */
    public function supports($object, $targetClass)
    {
        return ($object instanceof Product) && is_a($targetClass, ProductRepresentation::class, true);
    }

    /**
     * {@inheritdoc}
     */
    public function transform($object, $targetClass)
    {
    	/** @var Product $product */
    	$product = $object;

    	$purchasedCount = $this->productRepository->computePurchasedCount($product);

    	return new ProductRepresentation(
    		$product->getName(),
    		$product->getCategory()->getName(), 
    		$purchasedCount
    	);
    }
}

Register it:

<?php

$priority = 0;
$modelTransformer->addTransformer($productToProductRepresentationModelTransformer, $priority = 0);

With an optional priority integer (higher equals more important and therefore that the transformer will be triggered earlier) that determines when a transformer is triggered versus other transformers (defaults to 0).

Use it anywhere:

<?php

$productRepresentation = $modelTransformer->transform($product, ProductRepresentation::class);

If you have simple rules of transformation, you can use ObjectTransformerInterface instead. As bonus transformation will work much faster.

Specifications

All actual documentation is runnable library specifications at /spec directory.

And to ensure library is not broken, run (under library directory):

bin/phpspec run