README

The objective of this library is to centralize the logic in charge of transforming objects (usually models) into arrays in order to expose them through JSON. Eralda can transform any type of object (PHP standard objects, Laravel Eloquent models...) into an array by just indicating the desired property mapping.

Eralda also offers the possibility of transforming property values as well as embedding related elements (e.g. author → books).

Installation

You can install the package via composer:

composer require sportuondo/eralda

Usage

Given the following objects:

$tolkien = new Author();
$tolkien->id = 1;
$tolkien->name = 'J.R.R. Tolkien';
$tolkien->isFreelance = false;
$tolkien->birthDate = Carbon::createFromFormat('Y-m-d', '1892-01-03');

$hobbit = new Book();
$hobbit->id = 1;
$hobbit->author = $tolkien;
$hobbit->title = 'The Hobbit';
$hobbit->year = 1937;

$lotr = new Book();
$lotr->id = 2;
$lotr->author = $tolkien;
$lotr->title = 'The Lord of the Rings';
$lotr->year = 1968;

$this->tolkien->books = [
    $hobbit,
    $lotr
];

We can define the following Transformer:

class AuthorArrayTransformer extends ArrayTransformerAbstract
{
    protected $keysMap = [
        'id'          => 'id',
        'name'        => 'name',
        'isFreelance' => 'is_freelance',
        'birthDate'   => 'birth_date',
    ];
    
    protected function presentBirthDate($author)
    {
        return $author->birthDate->format('Y-m-d');
    }
}

The $keysMap property is used to define the mapping between the properties of the source object and the keys of the resulting array.

On the other hand, we have included a presenter to modify the resulting value of a property of the original object on the fly. The nomenclature to define presenters is composed of the keyword present followed by the property name of the original object in Camel Case format.

To execute the transformation we would do the following:

$authorTransformer = new AuthorArrayTransformer();
$authorArray = $authorTransformer->transformItem($tolkien);

json_encode($authorArray)

The resulting array would look like this:

{
  "id": 1,
  "name": "J.R.R. Tolkien",
  "is_freelance": false,
  "birth_date": "1892-01-03"
}

Transforming collections

In the same way that we transform a single object we can also transform a collection of them. Since we have an array of authors we could do the following:

$authorTransformer = new AuthorArrayTransformer();
$authorsArray = $authorTransformer->transformCollection($authors);

json_encode($authorsArray)

To get something like this:

{
  [
    {
      "id": 1,
      "name": "J.R.R. Tolkien",
      "is_freelance": false,
      "birth_date": "1892-01-03"
    },
    {
      "id": 2,
      "name": "Isaac Asimov",
      "is_freelance": false,
      "birth_date": "1920-01-02"
    }
  ]
}

Embedding additional elements

We can indicate the elements that we want to embed making use of the property $embeds:

Given the following book transformer:

class BookArrayTransformer extends ArrayTransformerAbstract
{
    protected $keysMap = [
        'id'     => 'id',
        'title'  => 'title',
        'author' => 'author',
        'year'   => 'year',
    ];

    protected function presentAuthor($book)
    {
        return $book->author->name;
    }
}

We could modify our transformer of authors in the following way:

class AuthorArrayTransformer extends ArrayTransformerAbstract
{
    protected $embeds = [
        'books',
    ];

    protected $keysMap = [
        'id'          => 'id',
        'name'        => 'name',
        'isFreelance' => 'is_freelance',
        'birthDate'   => 'birth_date',
    ];

    protected function presentBirthDate($author)
    {
        return $author->birthDate->format('Y-m-d');
    }

    protected function embedBooks($author)
    {
        $bookTransformer = new BookArrayTransformer();
        return $bookTransformer->transformCollection($author->books);
    }
}

In this case we want to embed the books belonging to the author. The nomenclature to define embeds is composed of the keyword embed followed by the name of the element we want to embed in Camel Case format.

The result would be something like this:

{
  [
    {
      "id": 1,
      "name": "J.R.R. Tolkien",
      "is_freelance": false,
      "birth_date": "1892-01-03",
      "books": [
        {
          "id": 1,
          "title": "The Hobbit",
          "author": "J.R.R. Tolkien",
          "year": 1937
        },
        {
          "id": 2,
          "title": "The Lord of the Rings",
          "author": "J.R.R. Tolkien",
          "year": 1968
        }
      ]
    },
    {
      "id": 2,
      "name": "Isaac Asimov",
      "is_freelance": false,
      "birth_date": "1920-01-02",
      "books": [
        {
          "id": 3,
          "title": "The Caves of Steel",
          "author": "Isaac Asimov",
          "year": 1954
        }
      ]
    }
  ]
}

Testing

composer test

Credits

• Sendoa Portuondo

License

The MIT License (MIT). Please see License File for more information.