json_decode() not working - php

Question

I am using ajax to send data with JSON and it keeps returning null. Here is the string I'm sending:
{"username":"HittmanA","code":"%601234567890-%3D~!%40%23%24%25%5E%26*()_%2Bqwertyuiop%5B%5D%5CQWERTYUIOP%7B%7D%7Casdfghjkl%3B'ASDFGHJKL%22zxcvbnm%2C%2FZXCVBNM%3C%3E%3F","name":"Untitled-1"}
It is sent via post. Here is the code I send it with:
function slash(strr){
var re = /([^a-zA-Z0-9])/g;
var str = strr;
var subst = '\$1';
var st = encodeURIComponent(str.replace(re,subst));
console.log("st");
return st;
}
function create() {
var info = {};
var code=editor.getValue();
info.username=username;
info.code=slash(code);
var name=document.getElementById('projectName').value;
name2=name;
info.name=slash(name2);
info=JSON.stringify(info);
console.log(info);
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (xhttp.readyState == 4 && xhttp.status == 200) {
document.getElementById("demo").innerHTML = xhttp.responseText;
}
};
xhttp.open("POST", "create_project.php", true);
xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhttp.send("info="+info);
}
When it gets received in the php file it is processed like this:
$info = $_POST['info'];
echo "<pre>".$info."</pre>";
//$info = urldecode($info);
$info = json_decode($info);
echo "<pre>".$info."</pre>";
However for some reason the json_decode() doest work. Again here is the JSON I'm sending:
{"username":"HittmanA","code":"%601234567890-%3D~!%40%23%24%25%5E%26*()_%2Bqwertyuiop%5B%5D%5CQWERTYUIOP%7B%7D%7Casdfghjkl%3B'ASDFGHJKL%22zxcvbnm%2C%2FZXCVBNM%3C%3E%3F","name":"Untitled-1"}
the first echo works correctly but the second one doesn't. How do I fix this?

Answer 1

json_decode() must be emitting an error which you are not checking. Functions like json_decode() and json_encode() do not display errors, you must use json_last_error and since PHP 5.5 there is also json_last_error_msg().
<?php
$str = '{"username":"HittmanA","code":"%601234567890-%3D~!%40%23%24%25%5E%26*()_%2Bqwertyuiop%5B%5D%5CQWERTYUIOP%7B%7D%7Casdfghjkl%3B\'ASDFGHJKL%22zxcvbnm%2C%2FZXCVBNM%3C%3E%3F","name":"Untitled-1"}';
var_dump($str);
var_dump(json_decode($str));
var_dump(json_last_error());
var_dump(json_last_error_msg());
The above outputs:
string(189) "{"username":"HittmanA","code":"%601234567890-%3D~!%40%23%24%25%5E%26*()_%2Bqwertyuiop%5B%5D%5CQWERTYUIOP%7B%7D%7Casdfghjkl%3B\'ASDFGHJKL%22zxcvbnm%2C%2FZXCVBNM%3C%3E%3F","name":"Untitled-1"}"
class stdClass#1 (3) {
public $username =>
string(8) "HittmanA"
public $code =>
string(136) "%601234567890-%3D~!%40%23%24%25%5E%26*()_%2Bqwertyuiop%5B%5D%5CQWERTYUIOP%7B%7D%7Casdfghjkl%3B\'ASDFGHJKL%22zxcvbnm%2C%2FZXCVBNM%3C%3E%3F"
public $name =>
string(10) "Untitled-1"
}
int(0)
string(8) "No error"
If we try to decode invalid JSON:
<?php
$str = 'foobar{';
var_dump($str);
var_dump(json_decode($str));
var_dump(json_last_error());
var_dump(json_last_error_msg());
The above prints:
string(7) "foobar{"
NULL
int(4)
string(16) "boolean expected"
There must be an error in the JSON when you try to decode it. Check for errors usings the json_* error message functions. The error message will tell you what's wrong and it will be straight to fix once you know what the error is.

Answer 2

hello mister if you echo in php is equal to return or print in some functional programming.
if your using ajax, ajax is one way communication.
$info = $_POST['info'];
//this code will be return
echo "<pre>".$info."</pre>";
//this also will not be triggered cause you already return the above code
//$info = urldecode($info);
$info = json_decode($info);
echo "<pre>".$info."</pre>";

Answer 3

Perhaps setting the xhttp content-type as json like
<?PHP
$data = /** whatever you're serializing **/;
header('Content-Type: application/json');
echo json_encode($data); ?>
As stated in this answer.

Answer 4

Looking at the object it looks like you have a ' inside your code parameter. I think that's invalid for encoding.

Answer 5

Using json_decode like this:
$info = json_decode($info);
Will return a PHP variable.
If you add the associative parameter as true (false by default) like this:
$info = json_decode($info, true);
Then it will return an associative array
http://php.net/manual/en/function.json-decode.php

Answer 6

I was struggling with this on my Windows 10 machine, PHP version 5.5.9 only to find that the php_json.dll file was not in the ext folder of my installation and obviously no extension to uncomment in php.ini file. I found the dll at http://originaldll.com/file/php_json.dll/31989.html. After copying it to my ext folder I added extension=php_json.dll to my php.ini file and restarted my apache server and it started working fine.