json_decode returns NULL (php)

Question

There is a strange behaviour with json_encode and json_decode and I can't find a solution:

My php application calls a php web service. The webservice returns json that looks like this:

var_dump($foo):
string(62) "{"action":"set","user":"123123123123","status":"OK"}"

now I like to decode the json in my application:

$data = json_decode($foo, true)

but it returns NULL:

var_dump($data):
NULL

I use php 5. The Content-Type of the response from the webservice: "text/html; charset=utf-8" (also tried to use "application/json; charset=utf-8")

What could be the reason?

Answer 1

Try this

$foo = utf8_encode($foo);
$data = json_decode($foo, true);

Answer 2

"{"action":"set","user":"123123123123","status":"OK"}"

This little apostrophe in the beginning - what is it? First symbol after the doublequote.

Answer 3

EDIT: Just did some quick inspection of the string provided by the OP. The small "character" in front of the curly brace is a UTF-8 B(yte) O(rder) M(ark) 0xEF 0xBB 0xBF. I don't know why this byte sequence is displayed as  here.

Essentially the system you aquire the data from sends it encoded in UTF-8 with a BOM preceding the data. You should remove the first three bytes from the string before you throw it into json_decode() (a substr($string, 3) will do).

string(62) "{"action":"set","user":"123123123123","status":"OK"}"
            ^
            |
            This is the UTF-8 BOM

As Kuroki Kaze discovered, this character surely is the reason why json_decode fails. The string in its given form is not correctly a JSON formated structure (see RFC 4627)

Answer 4

Well, i had a similar issue and the problems was the PHP magic quotes in the server... here is was my solution:

if(get_magic_quotes_gpc()){
  $d = stripslashes($_POST['param']);
}else{
  $d = $_POST['param'];
}
$d = json_decode($d,true);

Answer 5

Print the last json error when debugging.

json_decode( $so, true, 9 )
$json_errors = array(
    JSON_ERROR_NONE => 'No error has occurred',
    JSON_ERROR_DEPTH => 'The maximum stack depth has been exceeded',
    JSON_ERROR_CTRL_CHAR => 'Control character error, possibly incorrectly encoded',
    JSON_ERROR_SYNTAX => 'Syntax error',
);
 echo 'Last error : ', $json_errors[json_last_error()], PHP_EOL, PHP_EOL;

Also use the json.stringify() function to double check your JSON syntax.

Answer 6

i had a similar problem, got it to work after adding '' (single quotes) around the json_encode string. Following from my js file:

var myJsVar  = <?php echo json_encode($var); ?> ;    -------> NOT WORKING  
var myJsVar = '<?php echo json_encode($var); ?>' ;    -------> WORKING

just thought of posting it in case someone stumbles upon this post like me :)