passing JavaScript object to PHP not working

Question

I'm trying to send my javascript object to PHP via JSON.stringify()

Javascript:

$('#save').on('click touch', function(){
 obj = {
 "1" : {
 "1" : "hey",
 "2" : "hay"
 }, 
 "2" : {
 "1" : "hey",
 "2" : "hay"
 }
 }
 var json = JSON.stringify( obj );
 console.log(json)
 $.ajax({
 type: 'POST',
 url: 'ajax.php',
 success: function(data) {
 alert(data);
 $("p").text(data);
 }
 });
});

ajax.php:

<?php 
 $obj = json_decode($json);
 echo $obj;
?> 

But this code returns an error saying that $json is not defined. I have no idea why this is not working.

• Henrique Barcelos: You have not set the data attribute on $.ajax options.
• csum: POST data will be available in the $_POST variable in PHP
• Marc B: @csum: only if OP actually bothers to tell jquery to USE that json var in the ajax call...
• csum: @MarcB yup, true. It was more of a general statement. POST data is in $_POST
• Joost Hobma: I have fixed the issue. Thank you all

Answer 1

There are 2 problems.

1. You are not sending any data with the request
2. That's not the way you'll get the value from a request in PHP

First, add this*:

$.ajax({
 type: 'POST',
 url: 'ajax.php',
 data : { json: json }, // <---------------------
 ...

_{^{* this works just because jQuery implementation will automatically convert any non-string data argument into a form-urlencoded query string. See the docs.}}

Then, in your PHP, you should do:

$jsonStr = $_POST['json'];
$json = json_decode($jsonStr);

---

Edit:

Another possible way:

$.ajax({
 type: 'POST',
 url: 'ajax.php',
 data : json , // <---------------------
 ...

This way, your data will not be a valid form-urlencoded input, so PHP will not parse it into $_POST, but you still can get the contents of your input doing this:

$jsonStr = file_get_contents("php://input");
$json = json_decode($jsonStr);

• csum: Can you explain the reason behind the 2nd option not being a valid form-urlencoded input? Is it due to the contents of the json variable? The keys being numeric?
• Henrique Barcelos: form-urlencoded values are in the form param1=value1&param2=value2&param3=value3...
• Henrique Barcelos: Basically, it's a query string.
• csum: So then wrapping your var in {json: ___ } solves this?
• Henrique Barcelos: Solves because jQuery will automatically convert any object into a form-urlencoded string. Might not work in other Ajax libs.

Answer 2

Well - you never pass your data in the AJAX request!

$.ajax({
 type: 'POST',
 url: 'ajax.php',
 data: json //<---- RIGHT HERE
 success: function(data) {
 alert(data);
 $("p").text(data);
 }
});

• Steve: Thats half the problem
• Henrique Barcelos: In addition, OP should assing $json = $_POST['json'] unless OP has register_globals=On
• csum: don't forget the comma after json
• Marc B: @HenriqueBarcelos: uh, php has no idea what json is. a json string is just a plain text string to php. php expects key=value pairs in POST, value by itself is utterly meaningless. register_globals never did, and never will,decode json...
• Henrique Barcelos: I meant this part: $obj = json_decode($json). If register_globals=On and the data is passed under the 'json' key, like json={"foo":"bar"}, it would work.

Answer 3

You have to send the obj with the ajax request

 $.ajax({
 type: 'POST',
 url: 'ajax.php',
 data : json,
 dataType : 'json' // for json response
 ...

• Henrique Barcelos: dataType refers to the expected response, no the request.
• samleurs: @HenriqueBarcelos in the comment is says 'for json response'

Answer 4

Check here for reference jQuery ajax

Data parameter: Specifies data to be sent to the server.

Try this:

$('#save').on('click touch', function(){
 obj = {
 "1" : {
 "1" : "hey",
 "2" : "hay"
 }, 
 "2" : {
 "1" : "hey",
 "2" : "hay"
 }
}
var json = JSON.stringify( obj );
$.ajax({
 data : json,
 type: 'POST',
 url: 'ajax.php',
 success: function(data) {
 alert(data);
 $("p").text(data);
 }
});
});

• Henrique Barcelos: dataType refers to the expected response, no the request.

Answer 5

Replace your ajax code with this.

$.ajax({
 type: 'POST',
 url: 'ajax.php',
 data: json
 success: function(data) {
 alert(data);
 $("p").text(data);
 }
});

For ajax php

<?php 
 $obj = json_decode($_POST['data']);
 echo $obj;
?>