Experiment to decouple Entity from Eloquent

This experiment is based on Laracast Enforcement, Entities, and Eloquent video tutorial.

objective:

• to keep Entity as Plain Old PHP Object (POPO)
• to use Eloquent to persist and load entity without having to expose all fields via getters and setters
• to implement repository that use POPO entity for persistent and return POPO entity for query.

Approach

Student Entity

Student entity is just a simple PHP class with all attributes set as protected

namespace Acme;


class Student {

	protected $name;
	/**
	 * @var EmailAddress
	 */
	protected $email;
	/**
	 * @var Score
	 */
	protected $score;

	protected $id;

	protected function __construct($name, EmailAddress $email)
	{
		$this->name = $name;
		$this->email = $email;
		$this->score = new Score(100);
	}

	public static function register($name, $email){
		return new static($name, $email);
	}

	public function changeEmail(EmailAddress $email){
		$this->email = $email;
	}

	public function getId(){
		return $this->id;
	}
} 

StudentsRepository

Students repository explicitly define Student entity class.

interface StudentsRepository {
	/**
	 * @param Student $student
	 * @return mixed
	 */
	public function save(Student $student);

	/**
	 * @param $id
	 * @return Student
	 */
	public function find($id);

	/**
	 * @return Collection
	 */
	public function all();
} 

Eloquent implementation for StudentsRepository

Eloquent repository use an EloquentStudentProxy to map Student entity to eloquent model vice versa

<?php


namespace Acme\Adapter;

use Acme\Student;
use Acme\StudentsRepository;

class EloquentStudentsRepository implements StudentsRepository {

	public function save(Student $student)
	{
		$model = EloquentStudentProxy::toEloquent($student);
		$model->save();
	}

	public function find($id)
	{
		$model = EloquentStudent::find($id);
		return EloquentStudentProxy::toEntity($model);
	}

	public function all()
	{
		return EloquentStudent::all()->map(function($model){
			return EloquentStudentProxy::toEntity($model);
		});
	}
}

EloquentStudentProxy

Actually I not sure what to name this class and just call it as proxy. The main idea for this class is to map Student entity to eloquent model and create Student entity from eloquent model.

Since EloquentStudentProxy extends Student class, the class able to access all protected fields in Student class. This is to elinate needs for getter and setter and leave our entity with business logic only.

namespace Acme\Adapter;


use Acme\EmailAddress;
use Acme\Score;
use Acme\Student;

class EloquentStudentProxy extends Student{

	public static function toEloquent($student)
	{
		$model =  EloquentStudent::findOrNew($student->id);

		$model->fill([
			"name" => $student->name,
			"email" => (string) $student->email,
			"score" => (string) $student->score
		]);

		return $model;
	}

	public static function toEntity($model)
	{
		$student = new Student($model->name, new EmailAddress($model->email));
		$student->score = new Score($model->score);
		$student->id = $model->id;
		return $student;
	}
}

The Rest

Eloquent Model

So this is the eloquent model that used to persist the entity

namespace Acme\Adapter;


use Eloquent;

class EloquentStudent  extends Eloquent{
	protected $table = "students";
	protected $fillable = ["name", "email", "score"];

} 

The Controller

Register Student

public function store(){
	$student = Student::register(
		"John Doe",
		new EmailAddress("john.doe@email.com")
	);

	$this->repository->save($student);
}

Controller will use Student class to register student.

Retrieve student

public function show($id){
	$student = $this->repository->find($id);
	dd($student);
}

guess the output is:

object(Acme\Student)[137]
  protected 'name' => string 'John Doe' (length=8)
  protected 'email' => 
    object(Acme\EmailAddress)[146]
      private 'email' => string 'john.doe@email.com' (length=18)
  protected 'score' => 
    object(Acme\Score)[149]
      protected 'score' => string '100' (length=3)
  protected 'id' => string '1' (length=1)

change student email

public function update($id){
	$student = $this->repository->find($id);
	$student->changeEmail(new EmailAddress("changed@email.com"));

	$this->repository->save($student);
}

list all students

public function index(){
	dd($this->repository->all());
}