sorting json using php

Question

I'll try to sort a json format file by date and time

I try this method.

    function sortFunction( $a, $b ) {
        return strtotime($a["date"]) - strtotime($b["date"]);
    }

 $inp = file_get_contents('del.json');
$tempArray = json_decode($inp);
usort($tempArray, "sortFunction");
var_dump($tempArray);

del.json

[{"date":"2013-09-01 00:00:02","content":"1"},{"date":"2013-09-01 00:00:09","content":"5"},{"date":"2013-09-01 00:00:01","content":"3"}]

and ill get this error Cannot use object of type stdClass as array Thanks in advance!

I use this method and its work thanks to all your comment sorry i'm new bie hehe!

   function my_sort($a, $b)
    {
        if ($a->date < $b->date) {
            return -1;
        } else if ($a->date > $b->date) {
            return 1;
        } else {
            return 0; 
        }
    }

    usort($users, 'my_sort');

Your code is wrong here. PHP will not allow json-like direct declaration. Post your actual code, please. — Alma Do
– Alma Do, Commented Sep 9, 2013 at 8:30
I cannot reproduce it. As far as I know, your code triggers a parse error even in PHP 5.5. Is this your real code? — Álvaro González
– Álvaro González, Commented Sep 9, 2013 at 8:30
If you are getting json then use json_decode($data) before processing it — 웃웃웃웃웃
– 웃웃웃웃웃, Commented Sep 9, 2013 at 8:31
The array is malformed. AS @ÁlvaroG.Vicario said you should have a parse error. Take a look at error_reporting level — David Level
– David Level, Commented Sep 9, 2013 at 8:31
Whatever, I guess it's duplicate of Access JSON object name in PHP. Please have a look at it. — Álvaro González
– Álvaro González, Commented Sep 9, 2013 at 8:32

Fu Xu · Accepted Answer · 2013-09-09 10:07:34Z

0

two changes will make sence:

function sortFunction( $a, $b ) {
    return strtotime($a->date) > strtotime($b->date) ? 1 : -1;
}

or

$tempArray = json_decode($inp, TRUE);

answered Sep 9, 2013 at 10:07

Fu Xu

7562 gold badges6 silver badges21 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Daniel W. · Accepted Answer · 2013-09-09 08:45:41Z

The problem is that you don't understand the sort callback.

It's return value increases or decreases the index of the actual element (by +1 or -1).

http://php.net/usort

The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.

The second thing is, your json array gets decoded with an numeric array which is sorted by default

$tempArray[0] = ...
$tempArray[1] = ...
$tempArray[2] = ...

Important for the sorting callback is the KEY, not the values of your array.

Steps to make it work:

Decode the JSON array into PHP array
Put the Date, converted to DateTime object into the key

// Pseudo code:

$tempArray[DateTime Object] = Array(values);
use the usort with callback comparing the Date (>,<) instead of subtracting one by another (this is a semantical / logical error you have).

Tho, it would be easier to convert the Dates into unix timestamp and simply use natsort() on the array.

Collectives™ on Stack Overflow

sorting json using php

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related