How to receive data in php sent from javascript

Question

I am sending some data from my pain page to app.php using javascript

$(document).on('click', '.app' , function(){
        var data=$(this).attr("id");
        window.location="application/app.php?data="+data;   //data send in this statement
    });

my php code is this :

<?php
if($_GET['data'])
{
    echo $app_id=$_GET["data"]; receiving data 

}
?>

It works sometime but now it is giving Notice in an alert box: Undefined index data in app.php. But it is showing the echo.

I want to know how I can receive the data I need using $_POST or $_GET. like we receive by making an Ajax call. But I haven't specified something like this in Javascript. is there any way to this?

I want to clarify that the data exists and it is non empty because echo is successfully printing that on the page

*"It works sometime but now it is giving error"* Well... what did you change in the meantime? Is the problem that you don't receive the data at all or that you get this warning if you don't send data? — Felix Kling, Jul 03 '14 at 15:13
also check weather data variable is set or not before redirecting — NullPoiиteя, Jul 03 '14 at 15:19
@FelixKling I am receiving the data. But it is giving me notice in an alert box. I have done the same thing in my previous project exactly. But now is not working — stacky, Jul 03 '14 at 15:26
@NullPoiиteя if I am receiving the data from echo then what is the point in checking it before sending — stacky, Jul 03 '14 at 15:27

marty · Answer 1 · 2014-07-03T15:20:31.300

1

use isset() to first check if the key exists. data won't exist in $_GET when it's not passed via a parameter in the url

you probably want some logic that looks like this:

if (isset($_GET['data'])) {
    if (!empty($_GET['data'])) {
        $appId = $_GET['data'];
    }
    else {
        // data exists, but it's empty
    }
}
else {
    // data does not exist
}

and maybe you even want to check if it's a valid id, like being numeric or something

edited Jul 03 '14 at 15:20

answered Jul 03 '14 at 15:13

marty

651
7
13

using the examnple i added you can add some debug information in the if-else construct to track where it goes wrong – marty Jul 03 '14 at 15:21
`if (isset($_GET['data']) && !empty($_GET['data']))` will do the same – NullPoiиteя Jul 03 '14 at 15:21
also empty explicitly check isset – NullPoiиteя Jul 03 '14 at 15:21
the echo result is okay. it is showing the echo result. but there is an alert window also with showing the notice that "data" is an undefined index – stacky Jul 03 '14 at 15:22
@stacky Is that notice pointing to one of the lines in this answer? Sounds like you have something similar at another place in the code – kero Jul 03 '14 at 15:23
it is pointing only toward the data in the if condition @kingkero – stacky Jul 03 '14 at 15:25

szymanskilukasz · Accepted Answer · 2014-07-03T15:25:34.723

1

Try this:

<?php
if(!empty($_GET['data']))
{
    $app_id = $_GET['data']; // receiving data 
}
?>

Please be aware that passing data without validation is not secure. Reccomended reading: https://www.owasp.org/index.php/Category:OWASP_Top_Ten_Project

edited Jul 03 '14 at 15:25

answered Jul 03 '14 at 15:16

szymanskilukasz

463
3
13

"but there is an alert window" what alert window? You have some additional js code with alert? – szymanskilukasz Jul 03 '14 at 15:38
the answer is not correct. But u gave me the right direction. thanks man. The alert window was from a failed ajax call. thanks :) – stacky Jul 03 '14 at 15:45

How to receive data in php sent from javascript

2 Answers2