snipe-it/app/Http/Requests/SlackSettingsRequest.php

<?php

namespace App\Http\Requests;

class SlackSettingsRequest extends Request
{
    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize()
    {
        return true;
    }

    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    public function rules()
    {
        return [
            'slack_endpoint' => 'url|required_with:slack_channel|starts_with:https://hooks.slack.com|nullable',
            'slack_channel'                       => 'required_with:slack_endpoint|starts_with:#|nullable',
            'slack_botname'                       => 'string|nullable',

        ];
    }

    public function response(array $errors)
    {
        return $this->redirector->back()->withInput()->withErrors($errors, $this->errorBag);
    }
}