exposingdata.php

<?php

/*
 * Say you have an entity class which has no need to expose its internal data
 * fields in the business layer like so:
 */

class LibraryBook
{
    /** @var string */
    private $title;

    /** @var bool */
    private $isOnLoan;

    /** @var int */
    private $numberOfPages;

    /**
     * @param string $title
     * @param bool   $isOnLoan
     * @param int    $numberOfPages
     */
    public function __construct($title, $isOnLoan, $numberOfPages)
    {
        $this->title         = $title;
        $this->isOnLoan      = $isOnLoan;
        $this->numberOfPages = $numberOfPages;
    }

    public function checkOut()
    {
        $this->isOnLoan = true;
    }

    public function checkIn()
    {
        $this->isOnLoan = false;
    }

    /** @param int $numberOfPages */
    public function ripOutPages($numberOfPages)
    {
        $this->numberOfPages -= $numberOfPages;
    }
}

/*
 * How do you prefer to expose the internal fields for display & for your
 * storage layer to access them?
 */

// Option 1: Add getters

class LibraryBook
{
    // ...

    public function getTitle()
    {
        return $this->title;
    }

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

    public function getNumberOfPages()
    {
        return $this->numberOfPages;
    }
}

// Option 2: Return an array

class LibraryBook
{
    // ...

    public function asArray()
    {
        return [
            'title'         => $this->title,
            'onLoan'        => $this->isOnLoan,
            'numberOfPages' => $this->numberOfPages
        ];
    }
}

// Option 3: Return a DTO
// As Option 2 but return a BookDetails DTO object instead of a PHP array

class BookDetails
{
    /** @var string */
    private $title;

    /** @var bool */
    private $isOnLoan;

    /** @var int */
    private $numberOfPages;

    /**
     * @param string $title
     * @param bool   $isOnLoan
     * @param int    $numberOfPages
     */
    public function __construct($title, $isOnLoan, $numberOfPages)
    {
        $this->title         = $title;
        $this->isOnLoan      = $isOnLoan;
        $this->numberOfPages = $numberOfPages;
    }

    public function getTitle()
    {
        return $this->title;
    }

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

    public function getNumberOfPages()
    {
        return $this->numberOfPages;
    }
}

class LibraryBook
{
    // ...

    public function getDetails()
    {
        return new BookDetails(
            $this->title,
            $this->isOnLoan,
            $this->numberOfPages
        );
    }
}

// Option 4: Ask the entity to present it's data via an interface

interface BookDetailsReceiver
{
    /** @param $title string */
    public function setTitle($title);

    /** @param $isOnLoan bool */
    public function setOnLoanStatus($isOnLoan);

    /** @param $numPages int */
    public function setNumberOfPages($numPages);
}

class LibraryBook
{
    // ...

    public function presentDetails(BookDetailsReceiver $receiver)
    {
        $receiver->setTitle($this->title);
        $receiver->setOnLoanStatus($this->isOnLoan);
        $receiver->setNumberOfPages($this->numberOfPages);
    }
}

// Option 5: Some other way, please describe