SATE-EasyReceipt/app/Rules/ZipCode.php

<?php

namespace App\Rules;

class ZipCode extends BaseRule
{
    /**
     * Create a new rule instance.
     *
     * @return void
     */
    public function __construct()
    {
        //
    }


    public function check($value) : bool
    {
        return preg_match("/^\d{7}$/", $value) !== 0;
    }

    /**
     * Get the validation error message.
     *
     * @return string
     */
    public function message()
    {
        return '正しい郵便番号を入力してください';
    }
}