Sort object(SimpleXMLElement) php

Question

I'm trying to find a way to sort my array from SimpleXMLElement. I'd like to sort by start time which I can get from event_start_dt. I'd also like to sort by room ID as a separate process. Currently the array is in order by object(SimpleXMLElement) #. Here is the var_dump($array):

    object(SimpleXMLElement)#275 (1) { 
["reservation"]=> array(3) 
    { 
    [0]=> object(SimpleXMLElement)#287 (28) { 
        ["reservation_id"]=> string(7) "8644894" 
        ["event_start_dt"]=> string(25) "2013-12-02T12:00:00-08:00" 
        ["event_end_dt"]=> string(25) "2013-12-02T13:00:00-08:00" 
        ["event_id"]=> string(6) "314147" 
        ["event_name"]=> string(24) "Practice" 
        ["room_id"]=> string(3) "202"
    }
    [1]=> object(SimpleXMLElement)#288 (28) { 
        ["reservation_id"]=> string(7) "8595185" 
        ["event_start_dt"]=> string(25) "2013-12-02T08:00:00-08:00" 
        ["event_end_dt"]=> string(25) "2013-12-02T09:00:00-08:00" 
        ["event_id"]=> string(6) "314005"
        ["event_name"]=> string(24) "Meeting" 
        ["room_id"]=> string(3) "207"
    }
    [2]=> object(SimpleXMLElement)#289 (28) { 
        ["reservation_id"]=> string(7) "8718654" 
        ["event_start_dt"]=> string(25) "2013-12-02T10:00:00-08:00" 
        ["event_end_dt"]=> string(25) "2013-12-02T11:00:00-08:00" 
        ["event_id"]=> string(6) "315811" 
        ["event_name"]=> string(20) "Maintenance" 
        ["room_id"]=> string(3) "202"
    }
} }

I've tried usort and asort but haven't gotten it to work with either method.

usort method:

function sortByTime($a, $b){
    $a = strtotime($array->event_start_dt);
    $b = strtotime($array->event_start_dt);
        if ($a==$b) return 0;
        return ($a < $b) ?-1 : 1;
        }

        usort($arrTimes, 'sortByTime');

        var_dump($arrTimes);

Trying the code below gives me warning: usort() expects parameter 1 to be array, object given.

foreach ($rez->reservation as $value){ 
    $var1 = $value->space_reservation->space_name;
    $var2 = substr($value->event_start_dt,11,5);
}
sort_obj_arr($value,$var1,SORT_DESC);

echo "<pre>SORTED ";
print_r($value);
echo "</pre>";

function sort_obj_arr(& $arr, $sort_field, $sort_direction)
{
    $sort_func = function($obj_1, $obj_2) use ($sort_field, &$sort_direction)
    {
        if ($sort_direction == SORT_ASC) {
            return strnatcasecmp($obj_1->$sort_field, $obj_2->$sort_field);
        } else {
            return strnatcasecmp($obj_2->$sort_field, $obj_1->$sort_field);
        }
    };
    usort($arr, $sort_func);

}

I have an array from my controler but cannot get usort working: I get either: usort() expects parameter 1 to be array, object given or null.

$array = array($this->data);
print_r($array);

array(1) { 
[0]=> object(SimpleXMLElement)#280 (1) { ["reservation"]=> array(3) { 
        [0]=> object(SimpleXMLElement)#287 (28) { 
            ["reservation_id"]=> string(7) "8644894" 
            ["event_start_dt"]=> string(25) "2013-12-02T12:00:00-08:00" 
            ["event_end_dt"]=> string(25) "2013-12-02T13:00:00-08:00" 
            ["event_id"]=> string(6) "314147" 
            ["event_name"]=> string(24) "Practice" 
            ["room_id"]=> string(3) "202"
        }
        [1]=> object(SimpleXMLElement)#288 (28) { 
            ["reservation_id"]=> string(7) "8595185" 
            ["event_start_dt"]=> string(25) "2013-12-02T08:00:00-08:00" 
            ["event_end_dt"]=> string(25) "2013-12-02T09:00:00-08:00" 
            ["event_id"]=> string(6) "314005"
            ["event_name"]=> string(24) "Meeting" 
            ["room_id"]=> string(3) "207"
        }
        [2]=> object(SimpleXMLElement)#289 (28) { 
            ["reservation_id"]=> string(7) "8718654" 
            ["event_start_dt"]=> string(25) "2013-12-02T10:00:00-08:00" 
            ["event_end_dt"]=> string(25) "2013-12-02T11:00:00-08:00" 
            ["event_id"]=> string(6) "315811" 
            ["event_name"]=> string(20) "Maintenance" 
            ["room_id"]=> string(3) "202"
        }
    } }

Request for print_r:

SimpleXMLElement Object
(
    [reservation] => Array(3)
        (
            [0] => SimpleXMLElement Object
                (
                    [reservation_id] => 8604174
                    [event_start_dt] => 2013-12-31T06:00:00-08:00
                    [event_end_dt] => 2013-12-31T08:00:00-08:00
                    [event_id] => 314147
                    [event_name] => Practice
                    [room_id] => 202
                 )
         [1] => SimpleXMLElement Object
                (
                    [reservation_id] => 8604177
                    [event_start_dt] => 2013-12-31T05:00:00-08:00
                    [event_end_dt] => 2013-12-31T06:00:00-08:00
                    [event_id] => 314150
                    [event_name] => Meeting
                    [room_id] => 216
                 )
         [2] => SimpleXMLElement Object
                (
                    [reservation_id] => 8604189
                    [event_start_dt] => 2013-12-31T10:00:00-08:00
                    [event_end_dt] => 2013-12-31T11:00:00-08:00
                    [event_id] => 314150
                    [event_name] => Maintenance
                    [room_id] => 220
                 )
)
)

$arrTimes = xml2array($array->reservation);

var_dump($arrTimes)

array(5) { 
["reservation_id"]=> string(7) "8604175" 
["event_start_dt"]=> string(25) "2014-01-02T06:00:00-08:00" 
["event_end_dt"]=> string(25) "2014-01-02T08:00:00-08:00" 
["event_id"]=> string(6) "314147" 
["event_name"]=> string(24) "Practice" 
}

Answer 1

Before you can sort the data, you need to create an array which contains as its values the separate items you want to sort. From your debug outputs, these are multiple <reservation> nodes in the input XML, which are children of the element represented by $array/$this->data in those samples (it doesn't matter if it's the root of the document or not, SimpleXML has no Document object).

Your print_r and var_dump output shows that you do not currently have such an array, only a SimpleXML object:

• Your first example shows var_dump($array) giving output beginning object(SimpleXMLElement)#275 (1) { - ignore the word array further in, that's just how var_dump is rendering the insides of the object.
• Later, you have a print_r($array); beginning array(1) { - but this is only because you've wrapped the real data in a single-element array on the line above ($array = array($this->data);) and that one element ($array[0]) shows as object(SimpleXMLElement)#280 (1) { ....

Note that there's no need to go further and convert all the inner SimpleXML objects into arrays - you just need a list that is sortable, containing the items you are interested in. I would personally use a simple and explicit foreach loop, for maximum code readability, although "cleverer" solutions are available.

Once you have a sortable list, you need a callback function for usort which compares its two parameters. The attempt you've made is along the right lines, but refers to the non-existent (in that function) variable $array; the values you need to compare are the function's arguments, which you've called $a and $b - specifically, you want to compare strtotime($a->event_start_dt) with strtotime($b->event_start_dt).

You can also make the function much simpler, because it follows the common misconception that the return value of the callback should be -1, 0, or 1. In fact, it can be any integer, and only its sign matters - returning -42 will have the same effect as returning -999, namely placing item $a before $b in the resulting array.

I can't easily give a tested example, because you haven't provided the underlying XML to reproduce your input (e.g. echo $this->data->asXML();), but the basic approach I would take would be this:

// Start with an empty array, and add all the items we're interested in to it
$sortable_array = array();
// Loop over all <reservation> children of the SimpleXML object $this->data
// See http://php.net/manual/en/simplexml.examples-basic.php
foreach ( $this->data->reservation as $reservation_node )
{
    // Add the individual node to our array
    $sortable_array[] = $reservation_node;
}

// Now let's sort out the callback function for the sorting
// This could also be an anonymous function passed directly to usort
function sort_callback_event_start($a, $b)
{
    // $a and $b are both items in our $sortable_array, and therefore
    // <reservation> nodes which we expect to each have a child
    // called <event_start_dt>

    // If we convert both dates to Unix timestamps, we have two integers 
    // to compare, and a simple subtraction gives the desired result
    // of <0, 0, or >0 as documented at http://php.net/usort

    return
        strtotime((string)$a->event_start_dt)
        -
        strtotime((string)$b->event_start_dt);
}

// Now, we have everything we need to do the actual sorting
usort($sortable_array, 'sort_callback_event_start');
// $sortable_array is now sorted as desired! :D

// Note that the items within it are still SimpleXML objects, 
// so you still need to access their properties to do something useful
// e.g. some HTML output with the names listed in order of their start date:
echo '<ol>';
foreach ( $sortable_array as $reservation_node )
{
    echo '<li>', (string)$reservation_node->event_name, '</li>';
}
echo '</ol>';

Answer 2

I would just cast it as an array using this function (example function from php.net). But note that this will not sort the XML, rather sort the new array

/**
* function xml2array
*
* This function is part of the PHP manual.
*
* The PHP manual text and comments are covered by the Creative Commons 
* Attribution 3.0 License, copyright (c) the PHP Documentation Group
*
* @author  k dot antczak at livedata dot pl
* @date    2011-04-22 06:08 UTC
* @link    http://www.php.net/manual/en/ref.simplexml.php#103617
* @license http://www.php.net/license/index.php#doc-lic
* @license http://creativecommons.org/licenses/by/3.0/
* @license CC-BY-3.0 <http://spdx.org/licenses/CC-BY-3.0>
*/
function xml2array ( $xmlObject, $out = array () )
{
  foreach ( (array) $xmlObject as $index => $node )
    $out[$index] = ( is_object ( $node ) ) ? xml2array ( $node ) : $node;

   return $out;
 }

and pass it the XMLObject

$arrTimes = xml2array(YourSimpleXMLElement);

and then use your original usort function on the new array

 function sortByTime($a, $b){
    $a = strtotime($a['event_start_dt']);
    $b = strtotime($b['event_start_dt']);
    if ($a==$b) 
       return 0;
    return ($a < $b) ? -1 : 1;
 }

Finally

usort($arrTimes, 'sortByTime');

Answer 3

Use array_multisort

            foreach ($rez->reservation as $value)
            { 
                     $dateTime[] = $value->event_start_dt;
            }

           array_multisort($dateTime,SORT_ASC,SORT_STRING,$rez->reservation);   
           echo "<pre>";
           print_r($rez->reservation);

Check it. this is my code

<?php
        $myarray=array(
                    0 => array
                        (
                            'dateTime' => '2013-12-02T10:00:00-08:00',
                            'chanl1' => '20.10',
                            'chanl2' => '45.4',
                            'chanl3' => '',
                        ),

                    1 => array
                        (
                            'dateTime' => '2013-12-02T11:00:00-08:00',
                            'chanl1' => '20.11',
                            'chanl2' => '45.4',
                            'chanl3' => '',
                        ),
                  2 => array
                        (
                            'dateTime' => '2013-12-02T12:00:00-08:00',
                            'chanl1' => '20.12',
                            'chanl2' => '33.8',
                            'chanl3' => '',
                        ),

                    3 => array
                        (
                            'dateTime' => '2013-12-02T09:00:00-08:00',
                            'chanl1' => '20.9',
                            'chanl2' => '33.9',
                            'chanl3' => ''
                        ));

            foreach($myarray as $c=>$key) {
                    $dateTime[] = $key['dateTime'];                      
            }           


        array_multisort($dateTime,SORT_ASC,SORT_STRING,$myarray);   
        echo "<pre>";
        print_r($myarray);
        ?>

Output is :

Array
(
    [0] => Array
        (
            [dateTime] => 2013-12-02T09:00:00-08:00
            [chanl1] => 20.9
            [chanl2] => 33.9
            [chanl3] => 
        )

    [1] => Array
        (
            [dateTime] => 2013-12-02T10:00:00-08:00
            [chanl1] => 20.10
            [chanl2] => 45.4
            [chanl3] => 
        )

    [2] => Array
        (
            [dateTime] => 2013-12-02T11:00:00-08:00
            [chanl1] => 20.11
            [chanl2] => 45.4
            [chanl3] => 
        )

    [3] => Array
        (
            [dateTime] => 2013-12-02T12:00:00-08:00
            [chanl1] => 20.12
            [chanl2] => 33.8
            [chanl3] => 
        )

)

FIDDLE

Answer 4

You have to convert frist in to xml to array using json encode decode

$xml_array = json_decode(json_encode((array)$xml), TRUE);

u will get list of array....than u can sory according to date using strtotime function.