How to sort a JSON array with PHP

Question

First of all i'm a complete newbie to this, i have searched for solutions but none seem to do the trick.

So I am trying to sort this JSON array by date but i don't really know i should tackle this, any tips in the right direction are much appreciated!

["info":[
{"id":1, "title":"original title", "name":"john doe", "date":"2010-05-15"}, 
{"id":2, "title":"another title", "name":"foo bar", "date":"2009-04-11"},
...

So i'm getting the data like this

$data=file_get_contents('jsondata...');
$d=json_decode($data,true);

I would like to sort the data by date, any ideas how i should approach this? Is it also possible to return the year value only? So the output would be 2009 instead of 2009-04-11?

Thanks in advance

Use strtotime to turn it into a number and then sort by that? — Madara's Ghost
– Madara's Ghost, Commented Mar 21, 2012 at 16:28
How deep have you tried to dig into this? It doesn't seem like you've really tried to do what you're asking us to help you with. — Brian Driscoll
– Brian Driscoll, Commented Mar 21, 2012 at 16:30
@BrianDriscoll i have been playing with it for the past 2 days, i have read and tried many of the solutions i found on others questioning the same issue but i've probably been applying it wrongly since i am still very new to this. Sorry for asking help. — xtoffer
– xtoffer, Commented Mar 21, 2012 at 17:21

Ry- · Accepted Answer · 2018-07-09 15:53:42Z

24

You can use usort and a custom comparison function:

$data = '{"info":[{"id":1, "title":"original title", "name":"john doe", "date":"2010-05-15"}, {"id":2, "title":"another title", "name":"foo bar", "date":"2009-04-11"}]}';

$info = json_decode($data, true)['info'];

usort($info, function ($a, $b) {
    return $a['date'] <=> $b['date'];
});

<=> works on strings here because a string comparison is also a date comparison when your dates are formatted as YYYY-MM-DD.

Then, to show the year value for an entry, you can parse the date into a DateTime and reformat it:

$date = DateTime::createFromFormat('Y-m-d', $item['date']);
$year = $date->format('Y');

Here's a demo.

edited Jul 9, 2018 at 15:53

answered Mar 21, 2012 at 16:36

Ry-♦

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5 Comments

xtoffer Over a year ago

Thank you so much for this, got it working now! Thanks for your effort to explain this! I really appreciate it

Laci Over a year ago

@xtoffer You should accept an answer as correct so you don't just appreciate their effort to help you, but you can also help someone like me who has the same issue as you and I try to find out which answer from here is the correct one! Thank you in advance!

joshuahedlund Over a year ago

Note: As of PHP 5.2.2, DateTime objects can be compared using comparison operators, so you should just be able to return ($dA > $dB)

Ry- Over a year ago

@joshuahedlund: usort doesn’t expect a boolean return, but you’re right, it doesn’t make much sense to compare only the year even if you only show the year.

user982853 Over a year ago

Does this work on large lists? or just lists of two?

Frank van Wijk · Accepted Answer · 2012-03-21 16:31:34Z

0

You have to convert the date to a sortable format first. I think that strtotime() does the job. After that you can output whatever with strftime().

answered Mar 21, 2012 at 16:31

Frank van Wijk

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1 Comment

AbraCadaver Over a year ago

No need to convert if they're in this format 2010-05-15

cypher · Accepted Answer · 2012-03-21 16:37:34Z

0

Use uasort to sort the array with user-defined function and strtotime to parse the date to timestamp.

$json = '
    {"info":[
        {"id":1, "title":"original title", "name":"john doe", "date":"2010-05-15"}, 
        {"id":2, "title":"another title", "name":"foo bar", "date":"2009-04-11"}
        ]
    }';

$arr = json_decode($json)->info;
uasort($arr, function($item1, $item2){
    return strtotime($item1->date) > strtotime($item2->date);
});

Will output

Array
(
    [1] => stdClass Object
        (
            [id] => 2
            [title] => another title
            [name] => foo bar
            [date] => 2009-04-11
        )

    [0] => stdClass Object
        (
            [id] => 1
            [title] => original title
            [name] => john doe
            [date] => 2010-05-15
        )

)

answered Mar 21, 2012 at 16:37

cypher

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8 Comments

Ry- Over a year ago

You also don't need uasort because the keys are numeric, and ordering them maintaining the numeric keys can be incredibly confusing (in your output, 0 comes after 1).

cypher Over a year ago

Yes, it does and does so because I want it to. I don't want to modify the array any more then it's necessary for no reason. What if the key is actually important?

Ry- Over a year ago

I'll bet you $50 that the OP does not want item 1 to come before item 0 in the array, especially since it wasn't associative to begin with ;)

cypher Over a year ago

You can bet me whatever you want, I'm not changing indexes just because I think that I can.

Ry- Over a year ago

Sigh I don't think you understand how ridiculous having an array in that order with those keys is. But whatever.

|

Andreas Wong · Accepted Answer · 2012-03-21 16:40:09Z

0

Something like the following should get you started:

<?php

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

$input = array('info' => array(array('id' => 2, 'date' => '2019-04-11'), array('id' => 1, 'date' => '2010-05-15')));

usort($input['info'], 'sortDate');
print_r($input);

answered Mar 21, 2012 at 16:40

Andreas Wong

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1 Comment

xtoffer Over a year ago

Thank you for your feedback andreas i really appreciate it

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