Reorganization of Yii2 REST HAL implementation

model\User.php

<?php
namespace app\models;

use Yii;
use yii\web\Link;
use yii\web\Linkable;
use yii\helpers\Url;

// Use HAL trait
use yii\rest\hal\ArrayableTrait;


class User extends ActiveRecord implements IdentityInterface, Linkable
{
    use ArrayableTrait;

    public function extraFields()
    {
        return ['profile'];
    }

    public function getLinks()
    {
        return [
            Link::REL_SELF => Url::to(['user/view', 'id' => $this->id], true),
        ];
    }

    public function getProfile()
    {
        return $this->hasOne(Profile::className(), ['user_id' => 'id']);
    }
}

yii\base\ArraybleTrait.php

<?php
// Only showing the modifications in this class

// Removed the Link/Linkable 'use' on top
trait ArrayableTrait
{
    // ...
    public function toArray(array $fields = [], array $expand = [], $recursive = true)
    {
        $data = [];
        foreach ($this->resolveFields($fields, $expand) as $field => $definition) {
            $data[$field] = is_string($definition) ? $this->$definition : call_user_func($definition, $this, $field);
        }
        
        // Remove the Linkable stuff
        
        return $recursive ? ArrayHelper::toArray($data) : $data;
    }

    // Method required to be public
    public function resolveFields(array $fields, array $expand)
    {

yii\rest\hal\ArraybleTrait.php

<?php
use yii\helpers\ArrayHelper;
use yii\web\Link;
use yii\web\Linkable;

trait ArrayableTrait
{
    public function toArray(array $fields = [], array $expand = [], $recursive = true)
    {
        $data = [];
        foreach ($this->resolveFields($fields, $expand) as $field => $definition) {
            $value = is_string($definition) ? $this->$definition : call_user_func($definition, $this, $field);
            if (is_object($value)) {
                if ($recursive) {
                    $value = ($value instanceof Arrayable) ? $value->toArray() : ArrayHelper::toArray($value);
                }
                if (!isset($data['_embedded'])) {
                    $data['_embedded'] = [];
                }
                $data['_embedded'][$field] = $value;
            } elseif (is_array($value) && count($value)) {
                // If the first element is an object we assume a list of objects
                $first = current($value);
                if (is_object($first)) {
                    if (!isset($data['_embedded'])) {
                        $data['_embedded'] = [];
                    }
                    if (!isset($data['_embedded'][$field])) {
                        $data['_embedded'][$field] = [];
                    }
                    foreach($value as $k => $v) {
                        if ($recursive) {
                            $v = ($v instanceof Arrayable) ? $v->toArray() : ArrayHelper::toArray($v);
                        }
                        $data['_embedded'][$field][$k] = $value;
                    }
                } else {
                    $data[$field] = $value;
                }
            } else {
                $data[$field] = $value;
            }
        }

        if ($this instanceof Linkable) {
            $data['_links'] = Link::serialize($this->getLinks());
        }

        return $data;
    }
}