yii2/tests/unit/data/ar/mongodb/CustomerOrder.php

<?php

namespace yiiunit\data\ar\mongodb;

class CustomerOrder extends ActiveRecord
{
    public static function collectionName()
    {
        return 'customer_order';
    }

    public function attributes()
    {
        return [
            '_id',
            'number',
            'customer_id',
            'items',
        ];
    }

    public function getCustomer()
    {
        return $this->hasOne(Customer::className(), ['_id' => 'customer_id']);
    }
}