Convert JSON list to php array - php

Question

I am passing a list of numbers from a page to PHP serialized in JSON
{"items":"[1,2,3,4]"}
in my URL it is just
...&items={"items":[1,2,3,4]}
I decode this in PHP
$json = $_GET["items"];
$arr = json_decode($json, true);
I get an array
Array ( [items] => [1,2,4] )
But when I try a foreach on arr["items"] and print out each value, all I get is a single value
[1,2,4]
This is the code I am using to iterate
foreach($res["items"] as $value)
echo $value;
How come I am not getting something like
1
2
4

Answer 1

Look closely at your json string:
{"items":"[1,2,3,4]"}
Look closer:
"[1,2,3,4]"
You are saying that items is a string containing:
"[1,2,3,4]"
Remove the " and you'll be fine.

Answer 2

Your serialization is wrong. Should be:
{"items":[1,2,3]}
To get rid of problems like that use JSON.stringify in JS:
var myData = {"items" : [1,2,3]},
queryString = 'data='+encodeURIComponent(JSON.stringify(myData));
for IE < 8 it has to be included from external script (see here) :
<!--[if lt IE 8]><script src="/js/json2.js"></script><![endif]-->
Anyway much easier would be to send it already as an array:
items[0]=1&items[1]=2&items[2]=3
This way you can send also more complex structures:
data[items][0]=1&data[items][1]=2
// on PHP side will become
$_GET['data'] = array('items' => array(1,2))