validation.php

<?php
        $fields = [
            'title' => 'Your listing needs a title',
            'insurer_id' => 'Please specify an Insurer'
        ];

        $rules = [];

        foreach($fields as $field => $message){
            $rules['location_' . $field] = [
                'rule' => 'validateNotEmpty',
                'on' => [$this, 'onNotDraftStatus'],
                'pass' => [$field],
                'message' => $message
            ];
        }


        return $rules;