dnb-prospectus/src/Customer.php

<?php

namespace DNB;

class Customer extends AbstractPostSerializable implements PostSerializableInterface {
    public function __construct(
        private string $name,
        private ?string $email,
        private string $mobilePhone,
        private ?string $zipCode = null,
        private ?string $comment = null,
    ) {}

    public function toPostParams(): array {
        $arr = [];

        foreach (static::getClassVars() as $key)
            if (!is_null($this->{$key}))
                $arr[$key] = $this->{$key};

        return $arr;
    }

    protected static function getClassVars(): array {
        return array_keys(get_class_vars(__CLASS__));
    }
}