Php ajax call for same php script response null

Question

I am developing a single page script i.e. category.php for category management.

1. This script have an input button to invoke AJAX call.

<input type="button" id="btn" />

1. Jquery code to bind click event and call ajax. I want json response.

   $(document).ready(function(e) {
   $('#btn').click(function(e) {
           id=1;
           jQuery.ajax({
           type: 'post',
           url: 'category.php',
           success: function(data) {
               if(data.rstatus==1){
               alert(data.text);   
           }else
           alert(data);
       },
           data:{'id':id}
   
   
       }); 
       }); 
   });
   

2. A php code to entertain AJAX call.

   if(!empty($_SERVER['HTTP_X_REQUESTED_WITH']) &&
     strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest') {
       $jsonResponse=array('rstatus'=>1,'id'=>$_POST['id']);
       header("Content-type: application/json");   
       json_encode($jsonResponse);
       die(); 
    }
   

Problem:

This ajax call is unable to produce correct response in call back function, and cause error in firebug console. TypeError: data is null

In FIREBUG Headers are as follow:

Response Headers

> Cache-Control no-cache, must-revalidate Connection    Keep-Alive
> Content-Length    0 Content-Type  application/json Date   Tue, 26 Mar 2013
> 12:45:52 GMT Expires  Mon, 26 Jul 1997 05:00:00 GMT
> Keep-Alive    timeout=5, max=98 Last-Modified Tue, 26 Mar 2013
> 12:45:52GMT Pragma    no-cache Server Apache/2.4.3 (Win32) OpenSSL/1.0.1c
> PHP/5.4.7 X-Powered-By    PHP/5.4.7

Request Headers

> > Accept  */* Accept-Encoding gzip, deflate
>     > Accept-Language en-US,en;q=0.5 Content-Length   4
>     > Content-Type    application/x-www-form-urlencoded; charset=UTF-8
>     > Cookie  __gads=ID=39701a3d85dce702:T=1350383638:S=ALNI_MY_rHGVQ-qNxH4UGmbY_G-IuVcDkA;
>     > __utma=141011373.593047819.1350426838.1364292528.1364295112.314;PHPSESSID=1s73cho6ildjt80jtudt8nq0f5 Host   abc.com Referer http://www.abc.com/category.php
>     > User-Agent  Mozilla/5.0 (Windows NT 5.1; rv:19.0) Gecko/20100101
>     > Firefox/19.0 X-Requested-With   XMLHttpRequest

Answer 1

It's look like your response content is empty. You forgot an echo.

if(!empty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest') {
    $jsonResponse=array('rstatus'=>1,'id'=>$_POST['id']);
    header("Content-type: application/json"); 
    echo json_encode($jsonResponse); 
    die(); 
}

If you want to response a json, you must put it in the response content. In Php, you just have to use echo to put something in the response content.