json_decode() 不起作用

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

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 4

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 5

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

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.