Examples for how a __toArray() magic method could be useful in PHP.

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Examples for how a __toArray() magic method could be useful in PHP.

In a nutshell, __toArray() would not be as useful when you have full control over the entire codebase.

But where __toArray() would be extremely useful is in interfacing with existing code that expects arrays and wants those arrays to be a specific format. Using classes and type-hinted methods allow to encapsulate the intelligence into the class, and using __toArray() makes for a nature use-case.

use-with-mustache-php.php

<?php
//
// Use with https://github.com/bobthecow/mustache.php
//
class SaleableItem {
   private $id = false;
   private $mode = 'edit';
   
   // Other properties go here
   
   function __construct($id) {
      $this->id = $id;
   }
   function load() {
      // load data from DB
   }
   function __toArray():array {
      return array(
         'id' => 'add' === $this->mode ? null : $this->id,
         // Other properties go here
      );
   }
   function forAdd():self {
      $this->mode = 'add';
      return $this;
   }
   function forEdit():self {
      $this->mode = 'edit';
      return $this;
   }
}
$item = new SaleableItem('abc123');
$item->load();
$engine = new Mustache_Engine();
echo $engine->render( 'item-form', $item->forAdd() );

use-with-php-built-ins.php

<?php

class SaleableItemList {
   private $items = array();
   function load() {
      $items = DB::select("select * from items");
      foreach( $items as $item) {
         $this->items[] = new SaleableItem($item);
      }
   }
   function __toArray():array {
      return $this->items;
   }
}
$items = new SaleableItemList();
$items->load();
$names = array_column($items,'name');
$diff_0_vs_1 = array_diff_assoc($items[0],$items[1]);
$intersect_0_vs_1 = array_intersect_assoc($items[0],$items[1]);
$non_empty_props = array_filter($items[0]);
$empty_initial_values = array_fill_keys($items[0],null);
$elementa = array_keys($items[0]);
$sanitized = array_map(['Santizier','sanitize'],$items[0]);
$merged = array_merge_recursive($items[0],$items[1]);
$values = array_values($items[0]);

use-with-wordpress-1.php

<?php

class WP_Post {
   // Everything that is already in WP_Post
   private $mode = 'edit';
   function __toArray():array {
      $array = get_object_vars($this);
      if ('add'===$this->mode) {
         $array['ID'] = null;
      }
      return $array;
   }
   function forAdd():self {
      $this->mode = 'add';
      return $this;
   }
}
$post = new WP_Post();
// Get $post values from $_POST
wp_insert_post($post->forAdd());

use-with-wordpress-2.php

<?php

class Resource {
   private $url;
   private $params;
   function __construct(string $url, array $params) {
      $this->url = $url;
      $this->params = $params;
   }
   function __toString():string {
      return $this->url;
   }
   function __toArray():array {
      return $this->params;
   }
}
class Response {
   private $response;
   function __construct(string $response) {
      $this->response = !is_wp_error($response)
         ? $response
         : array();
   }
   function __toString():string {
      return wp_remote_retrieve_body($this);
   }
   function __toArray():array {
      return (array)$this;
   }
   function toJson():array {
      return json_decode($this);
   }
}

$resource = new Resource('http://api.acme.com/widget',['id'=>'abc123']);
$response = new Response( wp_remote_get($resource,$resource) );
echo $response->toJson();

use-with-wordpress-3.php

<?php
class AllowedHtml {
	private $allowed = array();
	public $default = array();
	function __construct( $allowed = array() ) {
		$this->default = $allowed;
	}
	function add_tag( string $tag, $attributes = array() ) {
		if ( isset( $this->allowed[ $tag ] ) ) {
			$attributes = array_merge( $this->allowed[ $tag ], $attributes );
		}
		$this->allowed[ $tag ] = new AllowedHtml($attributes);
	}
	function add_tags( array $tags ) {
		foreach( $tags as $key => $value ) {
			if ( is_array( $value ) ) {
				$allowed[ $key ] = new AllowedHtml( $value );
			} else {
				$allowed[ $value ] = new AllowedHtml();
			}
		}
	}
	function __toArray():array {
		return array_merge(
			$this->default, $this->allowed
		);
	}
}

/**
 * @See The following (mostly) replicates a much longer example from: 
 *      https://wp-mix.com/wordpress-basic-allowed-html-wp_kses/
 */
$allowed_html = new AllowedHtml( [ 'id', 'class', 'title', 'style', 'data' ] );
$allowed_html->add_tags( [ 'abbr', 'b', 'code', 'strike', 'strong', 'em', 'i' ] );
$allowed_html->add_tags( [ 'div', 'span', 'p' ] );
$allowed_html->add_tags( [ 'dd', 'dl', 'dt', 'li', 'ol', 'ul' ] );
$allowed_html->add_tags( [ 'h1', 'h2', 'h3', 'h4', 'h5', 'h6' ] );
$allowed_html->add_tag( 'a', [ 'rel' => [], 'href' => array( '_blank', '_top' ) ] );
$allowed_html->add_tag( 'blockquote', [ 'cite' ] );
$allowed_html->add_tag( 'q', [ 'cite' ] );
$allowed_html->add_tag( 'del', [ 'datetime' ] );
$allowed_html->add_tag( 'img', [ 'alt', 'height', 'width', 'src' ] );

$clean_html = wp_kses(
	$_POST[ 'content' ] ?? null,
	$allowed_html
);