Accessing JSON elements in PHP

Question

PHP noob here. I am building an iPhone app that is sending JSON blobs to a web server. On the server side I am receiving the JSON and trying to access the 3 fields that the object contains.

Two weird things are happening to me that I could not figure out how to fix:

1. I am not getting anything back when printing out the decoded object($post_data below).
2. I am actually able to print the full object back in Xcode when printing the object without decoding ($content below) but have no idea how to access the various fields in the object.

My PHP code:

$con = mysql_connect("127.0.0.1","root", "") or die('Could not connect: ' . mysql_error());
$content = file_get_contents('php://input');
$post_data = json_decode($content , true);
echo $content; --> prints the object properly 
echo $post_data; --> does not print anything
echo $content->lat; --> does not print anything

My JSON object:

{
 "lat" : 37.33233141,
 "long" : -122.0312186,
 "speed" : 0
}

Any help would be greatly appreciated.

• β.εηοιτ.βε: possible duplicate of PHP json_decode return empty array

Answer 1

it's because json_decode($content, true) is returning an array, which has problems displaying if you echo the container.

Try doing echo $post_data['lat'];

you can also try using print_r($post_data); to have it output the actual contents of the variable so you can see if something isn't working properly

• moshikafya: Wow thanks so much! I tried literally every single option but this is working! Would you mind a follow up question? Can I use '$post_data['lat']' as is if I want to store this parameter in a database? Thanks!!
• iam-decoder: definitely. Because using $post_data['lat'] will essentially replace the variable with it's contents in place. So you could be doing something like "UPDATE TABLE current_location SET lat = '".$post_data['lat']."', long = '".$post_data['long']."' WHERE current_user = '".$user_id."' LIMIT 1";