PHP loop through array of objects (JSON)

Question

PHP receives this via AJAX in JSON format (let's call it $json_string):

[{"pid":"284","qty":"1","sn":"12"},{"pid":"284","qty":"1","sn":"23"},{"pid":"276","qty":"1","sn":"34"},{"pid":"276","qty":"1","sn":"45"},{"pid":"276","qty":"1","sn":"56"},{"pid":"281","qty":"1","sn":"57"},{"pid":"281","qty":"1","sn":"67"},{"pid":"281","qty":"1","sn":"78"}]

I wish to loop through the arrays, like so:

$out = '<table>';
$arr = json_decode($json_string);
foreach ($arr AS $row){
    $out .= '<tr><td>'.$row['pid'].'</td><td>'.$row['qty'].'</td><td>'.$row['sn'].'</td></tr>';
}
$out .= '</table>';

I am getting an error: Fatal error: Cannot use object of type stdClass as array

Doesn't that mean that json_decode returns something that is NOT an array? — qwerty_so
– qwerty_so, Commented Jan 24, 2015 at 0:41
@ThomasKilian No, but $arr = json_decode($json_string, true) results in an associative array: $pid = $arr['pid']; -- whereas just $arr = json_decode($json_string) results in a simple array: $pid = $arr[0]; Depends on the data, not just the desired output. Above is assoc data. — crashwap
– crashwap, Commented Jan 24, 2015 at 1:05

prodigitalson · Accepted Answer · 2015-01-24 00:28:39Z

8

You need to force it to use an associative array:

$arr = json_decode($json_string, true);

Or modify your code to use object notation for the objects:

foreach ($arr AS $row){
    $out .= '<tr><td>'.$row->pid.'</td><td>'.$row->qty.'</td><td>'.$row->sn.'</td></tr>';
}

Personally I prefer forcing it all to an associative array because its easier to work with, especially when you get into complex nested structures.

answered Jan 24, 2015 at 0:28

prodigitalson

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1 Comment

ILikeTacos Over a year ago

It's stated pretty clear in json_decode documentation: php.net/manual/en/function.json-decode.php

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