Laravel/Eloquent Single Table Inheritance Trait

example.php

<?php

class Category extends Eloquent {
  
  use EloquentSingleTableInheritenceTrait;
  
  protected function singleTableInheritanceMpa()
  {
    return [
      1 => 'InventoryCategory',
      2 => 'PhotoCategory',
      3 => 'BrochureCategory',
    ];
  }
  
}

class InventoryCategory extends Category {
  
}

class PhotoCategory extends Category {
  
}

class BrochureCategory extends Category {
  
}

// usage:

$product->category_id; // 1
$product->category; // InventoryCategory

library.php

// EloquentSingleTableInheritenceTrait.php

<?php

trait EloquentSingleTableInheritenceTrait {

	protected function singleTableInheritanceKey()
	{
		return 'id';
	}

	protected function singleTableInheritanceMap()
	{
		return [];
	}

	public function newFromBuilder($attributes = array())
	{

		$inheritanceKey = $this->singleTableInheritanceKey();
		$inheritanceMap = $this->singleTableInheritanceMap();

		$key = $attributes->$inheritanceKey;

		if (array_key_exists($key, $inheritanceMap))
		{
			$instance = (new $inheritanceMap[$key])->newInstance([], true);

			$instance->setRawAttributes((array) $attributes, true);

			return $instance;
		}

		return parent::newFromBuilder($attributes);
	}

}