ldc-crm/app/Http/Requests/Api/V4/SingleOptinRequest.php

<?php

namespace App\Http\Requests\Api\V4;

class SingleOptinRequest extends BaseApiRequest
{
    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    public function rules(): array
    {
        return [
            'email'       => 'required|email:rfc,dns,spoof,filter',
            'opt_in'      => 'required|boolean',
            'answer_id'   => 'sometimes|array|min:1',
            'answer_id.*' => 'sometimes|integer|exists:answers,id',
        ];
    }
}