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 php5. 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

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)