XmlResponseFormatter useObjectTags

Module.php

<?php
namespace api\modules\v0;

use Yii;

class Module extends \yii\base\Module
{
    public function init()
    {
        parent::init();

        Yii::$app->response->on('beforeSend', function ($event) {
            /** @var \yii\web\Response $response */
            $response = $event->sender;
            if ($response->data && $response->getStatusCode() == 200) {
                $response->formatters['xml'] = [
                    'class' => 'api\components\XmlResponseFormatter',
                    'rootTag' => 'contacts',
                    'useObjectTags' => 'contact',
                ];
            }
        });
    }
}

XmlResponseFormatter.php

<?php

namespace api\components;

class XmlResponseFormatter extends \yii\web\XmlResponseFormatter
{
    /**
     * @var bool|string if object tags should be added
     * @since 2.0.11
     */
    public $useObjectTags = true;


    /**
     * @param DOMElement $element
     * @param mixed $data
     */
    protected function buildXml($element, $data)
    {
        if (is_array($data) ||
            ($data instanceof \Traversable && $this->useTraversableAsArray && !$data instanceof Arrayable)
        ) {
            foreach ($data as $name => $value) {
                if (is_int($name) && is_object($value)) {
                    $this->buildXml($element, $value);
                }

                $child = new DOMElement(is_int($name) ? $this->itemTag : $name);
                $element->appendChild($child);

                if (is_array($value) || is_object($value)) {
                    $this->buildXml($child, $value);
                } else {
                    $child->appendChild(new DOMText($this->formatScalarValue($value)));
                }
            }
        } elseif (is_object($data)) {
            if ($this->useObjectTags === true) {
                $child = StringHelper::basename(get_class($data));
            } else {
                $child = $this->useObjectTags;
            }
            
            $child = new DOMElement($child);
            $element->appendChild($child);

            if ($data instanceof Arrayable) {
                $this->buildXml($child, $data->toArray());
            } else {
                $array = [];
                foreach ($data as $name => $value) {
                    $array[$name] = $value;
                }
                $this->buildXml($child, $array);
            }
        } else {
            $element->appendChild(new DOMText($this->formatScalarValue($data)));
        }
    }
}