Exemplo de Helper. Campo input+request

CepHelper.php

<?php
App::import('Helper', 'AppHelper');

/**
 * Created by PhpStorm.
 * User: Ederlo Rodrigo de Oliveira
 * Date: 14/12/15
 * Time: 13:52
 */
class CepHelper extends AppHelper
{
    /**
     * @var array
     */
    public $helpers = array('Html', 'Form');

    /**
     * @var array
     */
    public $compoments = array('LocateMe');

    public function input($name, $data = array(), $others = array())
    {
        $class = ['class' => 'cep'];
        $input = $this->Form->input($name, array_merge($class, $data), $others)
        . '<script>'
        .'$(document).ready(function(){
            window.JSON_CEP = "";
            $(".'.$class['class'].'").on("change", function(){
                $.post("'.$this->Html->url('/',true).'user/users/api_locate.json",{cep : $(".'.$class['class'].'").val()} ,function(data){
                    window.JSON_CEP = data;
                    console.log(data);
                });
            });

        });'
        . '</script>';
        return ($input);
    }
}

Exemplo de Helper compatível com cake 2.x

para usar:

echo $this->Cep->input('nome');