Custom xml element - with default value getter

usage.php

<?php

$document = '
<document>
   <users>
      <id>1</id>
      <salary>120</salary>
      <is_admin>0</is_admin>
      <invalid-key/>
      <name>John Doe</name>
      <email>jdoe@example.com</email>
      <created_at>2018-07-12 17:06:13</created_at>
      <updated_at></updated_at>
   </users>
   <users>
      <id>2</id>
      <salary>120</salary>
      <is_admin></is_admin>
      <invalid-key>Test</invalid-key>
      <name>Gary Plant</name>
      <email>gplant@example.com</email>
      <created_at>2018-07-12 18:02:26</created_at>
      <updated_at>2018-07-13 11:22:44</updated_at>
   </users>
</document>';

$manifest = simplexml_load_string($document, XmlElement::class);

foreach($manifest->users as $user) {
    print_r([
        'id' => (int) $user->id,
        'salary' => $user->get('salary', 0),
        'is_admin' => (bool) $user->is_admin,
        // 'invalid_key' => $user->{"invalid-key"},
        'invalid_key' => $user->get('invalid-key'),
        'name' => $user->name,
        'email' => $user->email,
        // 'created_at' => $user->created_at, // Default = ''
        'created_at' => $user->get('created_at'), // Default = null
        'updated_at' => $user->get('updated_at'),
    ]);
}

XMLElement.php

<?php

/**
 * Custom XML element.
 */
class XMLElement extends \SimpleXMLElement
{
    /**
     * Provides access to element's children.
     *
     * With chance for default value.
     *
     * @param string $attr    Attribute
     * @param mixed  $default Default Value
     *
     * @return mixed
     */
    public function get($attr, $default = null)
    {
        if (empty($this->{$attr})) {
            return $default;
        }

        return $this->{$attr};
    }
}