How can I sort this array of objects with many properties in PHP?

Question

I have an array that contains multiple objects with many properties.

I want to sort it in PHP base on two object properties

Here's a sample array of objects to give you an idea of what data i'm dealing with:

Array (
    [0] => stdClass Object (
        [username] => user98
        [sender_id] => 98
        [date_sent] => 2012-07-25 00:52:11
        [not_read] => 0
    )
    [1] => stdClass Object (
        [username] => user87
        [sender_id] => 87
        [date_sent] => 2012-07-25 00:59:15
        [not_read] => 1
    )
    [2] => stdClass Object (
        [username] => user93
        [sender_id] => 93
        [date_sent] => 2012-07-25 00:52:13
        [not_read] => 2
    )
    [3] => stdClass Object (
        [username] => user5
        [sender_id] => 5
        [date_sent] => 2012-07-25 00:52:16
        [not_read] => 0
    )
)

I need to sort it resulting to this array:

Array (
    [1] => stdClass Object (
        [username] => user87
        [sender_id] => 87
        [date_sent] => 2012-07-25 00:59:15
        [not_read] => 1
    )
    [2] => stdClass Object (
        [username] => user93
        [sender_id] => 93
        [date_sent] => 2012-07-25 00:52:13
        [not_read] => 2
    )
    [3] => stdClass Object (
        [username] => user5
        [sender_id] => 5
        [date_sent] => 2012-07-25 00:52:16
        [not_read] => 0
    )

    [0] => stdClass Object (
        [username] => user98
        [sender_id] => 98
        [date_sent] => 2012-07-25 00:52:11
        [not_read] => 0
    )


)

The sorting is based on the date property and the not_read property of the object, the not_read > 0 is prioritized first in the sorting, then it will look at the date_sent property and sort it on the latest date_sent. Note that it is not based on who has the higher not_read property.

Then those with 0 not_read property will be sorted by latest date_sent.

Can anyone help me with this program?

thanks a lot of looking!

Patrick · Accepted Answer · 2012-07-24 17:27:17Z

4

You need to use a user-defined sort function:

function sortByDate($a, $b)
{
    if($a->not_read > $b->not_read)
        return 1;
    if($a->not_read < $b->not_read)
        return -1;
    if(strtotime($a->date_sent) > strtotime($b->date_sent))
        return 1;
    if(strtotime($a->date_sent) < strtotime($b->date_sent))
        return -1;
    return 0;
}

Then call it with usort:

usort($array_to_sort, 'sortByDate');

The array passed in will now be sorted.

answered Jul 24, 2012 at 17:27

Patrick

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2 Comments

Kevin Lee Over a year ago

i got confused from this code, i mean if the if statement in the $a->not_read returns already, then how will the code reach to the strtotime?

Patrick Over a year ago

@KevinLee since your first sorting criteria is for the not_read property, the date_sent doesn't matter. Only for the objects where the not_read property are the same would you need to worry about the date_sent property.

Matthew Scragg · Accepted Answer · 2012-07-24 17:47:02Z

1

function sortByDate($a, $b)
{
    if($a->not_read > 0 && $b->not_read == 0)
        return -1;
    if($b->not_read > 0 && $a->not_read == 0)
        return 1;
    if ($a->not_read == 0 && $b->not_read == 0 || $a->not_read > 0 && $b->not_read > 0){
        if(strtotime($a->date_sent) > strtotime($b->date_sent))
            return -1;
        if(strtotime($a->date_sent) < strtotime($b->date_sent))
            return 1;
    }

    return 0;
}

usort($array_to_sort, 'sortByDate');

Note: I would of made an edit to Patrick's but I wasn't sure if mine even worked. He was on the right track.

edited Jul 24, 2012 at 17:47

answered Jul 24, 2012 at 17:41

Matthew Scragg

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3 Comments

Patrick Over a year ago

@MatthewScragg the conditional isn't correct for the not_read property in your sort function. You checking only if the two comparing objects have a not_read property of > 0 and the other MUST have a not_read property of 0, in the example the OP gives there are three values given for not_read: 0,1,2. The sort function will not sort those objects properly.

Matthew Scragg Over a year ago

@Patrick Read the OP again, it appears he doesn't care what the not_read is, just as long not_read > 0 is in front AND still sorted by date.

Patrick Over a year ago

@MatthewScragg ah, missed that part.

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