invoiceninja/app/Http/Requests/Expense/UploadExpenseRequest.php

<?php
/**
 * Invoice Ninja (https://invoiceninja.com).
 *
 * @link https://github.com/invoiceninja/invoiceninja source repository
 *
 * @copyright Copyright (c) 2023. Invoice Ninja LLC (https://invoiceninja.com)
 *
 * @license https://www.elastic.co/licensing/elastic-license
 */

namespace App\Http\Requests\Expense;

use App\Http\Requests\Request;

class UploadExpenseRequest extends Request
{
    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize() : bool
    {
        return auth()->user()->can('edit', $this->expense);
    }

    public function rules()
    {
        $rules = [];

        if($this->file('documents') && is_array($this->file('documents')))
            $rules['documents.*'] = $this->file_validation;
        elseif($this->file('documents'))
            $rules['documents'] = $this->file_validation;

        if ($this->file('file') && is_array($this->file('file'))) {
            $rules['file.*'] = $this->file_validation;
        } elseif ($this->file('file')) {
            $rules['file'] = $this->file_validation;
        }

        return $rules;
    }
}