gistfile1.php

<?php

    public function zipcodeToRegion($zipcode, $zipcodeField = 'id', $regionField = 'id')
    {
        $result = $this
                        ->find()
                        ->select($regionField)
                        ->join([
                            [
                                'table' => 'provinces',
                                'type' => 'INNER',
                                'conditions' => 'provinces.region_id = Regions.id',
                            ],
                            [
                                'table' => 'cities',
                                'type' => 'INNER',
                                'conditions' => 'cities.province_id = provinces.id',
                            ],
                            [
                                'table' => 'zipcodes',
                                'type' => 'INNER',
                                'conditions' => [
                                    'zipcodes.city_id = cities.id',
                                    "zipcodes.$zipcodeField" => $zipcode
                                ]
                            ]
                        ])
                        ->first();
        
        if ($result)
        {
            return $result->id;
        }
        
        return null;
    }