PHP Array sorting by parent

Question

I got a complex array to be sorted, it looks like this:

Array
(
    [0] => Array
        (
            [id] => 1171409310
            [parent] => 1171287657
            [createdAt] => 2013-12-20T12:42:19
        )

    [1] => Array
        (
            [id] => 1171360372
            [parent] => 1171313704
            [createdAt] => 2013-12-20T11:18:46
        )

    [2] => Array
        (
            [id] => 1171313704
            [parent] => 1171304353
            [createdAt] => 2013-12-20T10:14:46
        )

    [3] => Array
        (
            [id] => 1171304353
            [parent] => 1171287657
            [createdAt] => 2013-12-20T09:55:34
        )

    [4] => Array
        (
            [id] => 1171303539
            [parent] => 1171014482
            [createdAt] => 2013-12-20T09:53:54
        )

    [5] => Array
        (
            [id] => 1171287657
            [parent] => 1170597579
            [createdAt] => 2013-12-20T09:29:34
        )

    [6] => Array
        (
            [id] => 1171264520
            [parent] => 1169354287
            [createdAt] => 2013-12-20T08:58:26
        )

    [7] => Array
        (
            [id] => 1171014482
            [parent] => 
            [createdAt] => 2013-12-20T02:51:24
        )

    [8] => Array
        (
            [id] => 1170700661
            [parent] => 1170597579
            [createdAt] => 2013-12-19T21:30:31
        )

    [9] => Array
        (
            [id] => 1170597579
            [parent] => 
            [createdAt] => 2013-12-19T20:22:40
        )

    [10] => Array
        (
            [id] => 1169362457
            [parent] => 
            [createdAt] => 2013-12-18T22:27:28
        )

    [11] => Array
        (
            [id] => 1169354287
            [parent] => 
            [createdAt] => 2013-12-18T22:20:08
        )

    [12] => Array
        (
            [id] => 1169315244
            [parent] => 
            [createdAt] => 2013-12-18T21:52:59
        )

)

I want the array to be first sorted by date (oldest on the top) and then each child after its parent (oldest on the top as well). The problem is that children can also be parents who have children as well so there are multiple dimensions. If possible I want also add the dimension.

I hope that my problem is clear.

EDIT: I get the array from the disqus API and want it to be sorted like it is on a website.

EDIT: It has to end like this:

Array
(
    [12] => Array
        (
            [id] => 1169315244
            [parent] => 
            [createdAt] => 2013-12-18T21:52:59
        )

    [11] => Array
        (
            [id] => 1169354287
            [parent] => 
            [createdAt] => 2013-12-18T22:20:08
        )

    [6] => Array
        (
            [id] => 1171264520
            [parent] => 1169354287
            [createdAt] => 2013-12-20T08:58:26
        )

    [10] => Array
        (
            [id] => 1169362457
            [parent] => 
            [createdAt] => 2013-12-18T22:27:28
        )

    [9] => Array
        (
            [id] => 1170597579
            [parent] => 
            [createdAt] => 2013-12-19T20:22:40
        )

    [8] => Array
        (
            [id] => 1170700661
            [parent] => 1170597579
            [createdAt] => 2013-12-19T21:30:31
        )

    [5] => Array
        (
            [id] => 1171287657
            [parent] => 1170597579
            [createdAt] => 2013-12-20T09:29:34
        )

    [3] => Array
        (
            [id] => 1171304353
            [parent] => 1171287657
            [createdAt] => 2013-12-20T09:55:34
        )

    [2] => Array
        (
            [id] => 1171313704
            [parent] => 1171304353
            [createdAt] => 2013-12-20T10:14:46
        )

    [1] => Array
        (
            [id] => 1171360372
            [parent] => 1171313704
            [createdAt] => 2013-12-20T11:18:46
        )

    [0] => Array
        (
            [id] => 1171409310
            [parent] => 1171287657
            [createdAt] => 2013-12-20T12:42:19
        )

    [7] => Array
        (
            [id] => 1171014482
            [parent] => 
            [createdAt] => 2013-12-20T02:51:24
        )


    [4] => Array
        (
            [id] => 1171303539
            [parent] => 1171014482
            [createdAt] => 2013-12-20T09:53:54
        )

)

Answer 1

uasort($array, function($a, $b) {   
    // sort by date first
    if (@$a["createdAt"] == @$b["createdAt"]){
        return 0;
    }
    return (@$a["createdAt"] > @$b["createdAt"]) ? 1 : -1;
});
$array_asc = array();
foreach($array as $key => $val){ 
    // create an array with ids as keys and children
    // with the assumption that parents are created earlier. 
    // store the original key
    $array_asc[$val['id']] = array_merge($val, array('org_key' => $key)); 
    if ($val['parent']){
        $array_asc[$val['parent']]['children'][] = $val['id'];
    }
}
$array_out = array();

// get a flat array again

foreach($array_asc as $val){
    if ($val['parent']){
        continue;         
    }
    add_to_output($array_out, $val, $array_asc);
}

function add_to_output(&$array_out, $val, $array_asc){ 
    $array_out[$val['org_key']] = $val;
    if (sizeof($val['children'])){
        foreach($val['children'] as $id){
            add_to_output($array_out, $array_asc[$id], $array_asc);
        }
    }
    unset($array_out[$val['org_key']]['children'], $array_out[$val['org_key']]['org_key']);
}

not tested.

Answer 2

I'm building a comment system myself, currently. Just ordering the comments like this is not going to really give you a strong relationship between comments (a parent-child relationship).

In this case, I'd do the following:

$comments = array();
foreach ($results as $result) {
    if ($result["parent"]) {
        $result["children"] = array();
        $comments[$result["id"]] = $result;
    }
}

// Have yet to do this a better way. Second loop is there for a reason.
foreach ($results as $result) {
    if ($result["parent"])
        $comments[$result["parent"]]["children"] = $result;
}

var_dump($comments);
// you can now sort on createdAt using uasort(array $array, callable $func)

uasort($comments, function ($a, $b) {
    if ($a["createdAt"] == $b["createdAt"])
        return 0;
    return ($a["createdAt"] > $b["createdAt"]) ? 1 : -1;
    // reverse this to change sort order
});

Answer 3

you can user the php array_multisort

you probably want to build your array like this

<?php
function array_orderby()
{
    $args = func_get_args();
    $data = array_shift($args);
    foreach ($args as $n => $field) {
        if (is_string($field)) {
            $tmp = array();
            foreach ($data as $key => $row)
                $tmp[$key] = $row[$field];
            $args[$n] = $tmp;
            }
    }
    $args[] = &$data;
    call_user_func_array('array_multisort', $args);
    return array_pop($args);
}
?>


<?php
$data[] = array('createdAt' => 67, 'parent' => 2);
$data[] = array('createdAt' => 86, 'parent' => 1);
$data[] = array('createdAt' => 85, 'parent' => 6);
$data[] = array('createdAt' => 98, 'parent' => 2);
$data[] = array('createdAt' => 86, 'parent' => 6);
$data[] = array('createdAt' => 67, 'parent' => 7);

// Pass the array, followed by the column names and sort flags
$sorted = array_orderby($name_of_array, 'createdAt', SORT_DESC, 'parent', SORT_ASC);
?>