Sort array of objects by object fields

Question

How can I sort this array of objects by one of its fields, like name or count ?

  Array
(
    [0] => stdClass Object
        (
            [ID] => 1
            [name] => Mary Jane
            [count] => 420
        )

    [1] => stdClass Object
        (
            [ID] => 2
            [name] => Johnny
            [count] => 234
        )

    [2] => stdClass Object
        (
            [ID] => 3
            [name] => Kathy
            [count] => 4354
        )

   ....

Answer 1

Use usort, here's an example adapted from the manual:

function cmp($a, $b) {
    return strcmp($a->name, $b->name);
}

usort($your_data, "cmp");

You can also use any callable as the second argument. Here are some examples:

• Using anonymous functions (from PHP 5.3)

    usort($your_data, function($a, $b) {return strcmp($a->name, $b->name);});
  

• From inside a class

    usort($your_data, array($this, "cmp")); // "cmp" should be a method in the class
  

• Using arrow functions (from PHP 7.4)

    usort($your_data, fn($a, $b) => strcmp($a->name, $b->name));
  

Also, if you're comparing numeric values, fn($a, $b) => $a->count - $b->count as the "compare" function should do the trick, or, if you want yet another way of doing the same thing, starting from PHP 7 you can use the Spaceship operator, like this: fn($a, $b) => $a->count <=> $b->count.

Answer 2

Heres a nicer way using closures

usort($your_data, function($a, $b)
{
    return strcmp($a->name, $b->name);
});

Please note this is not in PHP's documentation but if you using 5.3+ closures are supported where callable arguments can be provided.

Answer 3

If you want to sort integer values:

// Desc sort
usort($array,function($first,$second){
    return $first->number < $second->number;
});

// Asc sort
usort($array,function($first,$second){
    return $first->number > $second->number;
});

UPDATED with the string don't forget to convert to the same register (upper or lower)

// Desc sort
usort($array,function($first,$second){
    return strtolower($first->text) < strtolower($second->text);
});

// Asc sort
usort($array,function($first,$second){
    return strtolower($first->text) > strtolower($second->text);
});

Answer 4

if you're using php oop you might need to change to:

public static function cmp($a, $b) 
{
    return strcmp($a->name, $b->name);
}

//in this case FUNCTION_NAME would be cmp
usort($your_data, array('YOUR_CLASS_NAME','FUNCTION_NAME')); 

Answer 5

usort($array, 'my_sort_function');

var_dump($array);

function my_sort_function($a, $b)
{
    return $a->name < $b->name;
}

The same code will be with the count field.

More details about usort: http://ru2.php.net/usort

Btw, where did you get that array from? I hope that not from database?

Answer 6

You can use this function (works in PHP Version >= 5.3):

function sortArrayByKey(&$array,$key,$string = false,$asc = true){
    if($string){
        usort($array,function ($a, $b) use(&$key,&$asc)
        {
            if($asc)    return strcmp(strtolower($a{$key}), strtolower($b{$key}));
            else        return strcmp(strtolower($b{$key}), strtolower($a{$key}));
        });
    }else{
        usort($array,function ($a, $b) use(&$key,&$asc)
        {
            if($a[$key] == $b{$key}){return 0;}
            if($asc) return ($a{$key} < $b{$key}) ? -1 : 1;
            else     return ($a{$key} > $b{$key}) ? -1 : 1;

        });
    }
}

Example:

sortArrayByKey($yourArray,"name",true); //String sort (ascending order)
sortArrayByKey($yourArray,"name",true,false); //String sort (descending order)
sortArrayByKey($yourArray,"id"); //number sort (ascending order)
sortArrayByKey($yourArray,"count",false,false); //number sort (descending order)

Answer 7

If everything fails here is another solution:

$names = array(); 
foreach ($my_array as $my_object) {
    $names[] = $my_object->name; //any object field
}

array_multisort($names, SORT_ASC, $my_array);

return $my_array;

Answer 8

You can use usort, like this:

usort($array,function($first,$second){
    return strcmp($first->name, $second->name);
});

Answer 9

Downside of all answers here is that they use static field names, so I wrote an adjusted version in OOP style. Assumed you are using getter methods you could directly use this Class and use the field name as parameter. Probably someone find it useful.

class CustomSort{

    public $field = '';

    public function cmp($a, $b)
    {
        /**
         * field for order is in a class variable $field
         * using getter function with naming convention getVariable() we set first letter to uppercase
         * we use variable variable names - $a->{'varName'} would directly access a field
         */
        return strcmp($a->{'get'.ucfirst($this->field)}(), $b->{'get'.ucfirst($this->field)}());
    }

    public function sortObjectArrayByField($array, $field)
    {
        $this->field = $field;
        usort($array, array("Your\Namespace\CustomSort", "cmp"));;
        return $array;
    }
} 

Answer 10

if you want to sort dates

   usort($threads,function($first,$second){
        return strtotime($first->dateandtime) < strtotime($second->dateandtime);
    });

Answer 11

If you need local based string comparison, you can use strcoll instead of strcmp.

Remeber to first use setlocale with LC_COLLATE to set locale information if needed.

  usort($your_data,function($a,$b){
    setlocale (LC_COLLATE, 'pl_PL.UTF-8'); // Example of Polish language collation
    return strcoll($a->name,$b->name);
  });

Answer 12

A simple alternative that allows you to determine dynamically the field on which the sorting is based:

$order_by = 'name';
usort($your_data, function ($a, $b) use ($order_by)
{
    return strcmp($a->{$order_by}, $b->{$order_by});
});

This is based on the Closure class, which allows anonymous functions. It is available since PHP 5.3.

Answer 13

If you are using this inside Codeigniter, you can use the methods:

usort($jobs, array($this->job_model, "sortJobs"));  // function inside Model
usort($jobs, array($this, "sortJobs")); // Written inside Controller.

@rmooney thank you for the suggestion. It really helps me.

Answer 14

Thanks for the inspirations, I also had to add an external $translator parameter

usort($listable_products, function($a, $b) {
    global $translator;
    return strcmp($a->getFullTitle($translator), $b->getFullTitle($translator));
});

Answer 15

If you need to sort by only one field, then usort is a good choice. However, the solution quickly becomes messy if you need to sort by multiple fields. In this case, YaLinqo library* can be used, which implements SQL-like query syntax for arrays and objects. It has a pretty syntax for all cases:

$sortedByName         = from($objects)->orderBy('$v->name');
$sortedByCount        = from($objects)->orderBy('$v->count');
$sortedByCountAndName = from($objects)->orderBy('$v->count')->thenBy('$v->name');

Here, '$v->count' is a shorthand for function ($v) { return $v->count; } (either can be used). These method chains return iterators, but you can get arrays by adding ->toArray() in the end if you need it.

_{* developed by me}

Answer 16

You can use sorted function from Nspl:

use function \nspl\a\sorted;
use function \nspl\op\propertyGetter;
use function \nspl\op\methodCaller;

// Sort by property value
$sortedByCount = sorted($objects, propertyGetter('count'));

// Or sort by result of method call
$sortedByName = sorted($objects, methodCaller('getName'));

Answer 17

This is what I have for a utility class

class Util
{
    public static function sortArrayByName(&$arrayToSort, $meta) {
        usort($arrayToSort, function($a, $b) use ($meta) {
            return strcmp($a[$meta], $b[$meta]);
        });
    }
}

Call it:

Util::sortArrayByName($array, "array_property_name");

Answer 18

You can use usort like this

If you want to sort by number:

function cmp($a, $b)
{
    if ($a == $b) {
        return 0;
    }
    return ($a < $b) ? -1 : 1;
}

$a = array(3, 2, 5, 6, 1);

usort($a, "cmp");

Or Abc char:

function cmp($a, $b)
{
    return strcmp($a["fruit"], $b["fruit"]);
}

$fruits[0]["fruit"] = "lemons";
$fruits[1]["fruit"] = "apples";
$fruits[2]["fruit"] = "grapes";

usort($fruits, "cmp");

See more: https://www.php.net/manual/en/function.usort.php

Answer 19

reference answer of Demodave to eating multi key

 function array_sort_by(array $arr, $keys){

    if(!is_array($keys))
        $keyList = explode(',', $keys);
    $keyList = array_keys(array_flip($keyList)); // array_unique 
    $keyList = array_reverse($keyList);

    $result = &$arr;
    foreach ($keyList as $key) {
        if(array_key_exists($key, $arr))
            $result = usort($result, function($a, $b) use ($key) { return strcmp($a->{$key}, $b->{$key}); });
    }
    return $result;
}

Answer 20

$array[0] = array('key_a' => 'z', 'key_b' => 'c');
$array[1] = array('key_a' => 'x', 'key_b' => 'b');
$array[2] = array('key_a' => 'y', 'key_b' => 'a');

function build_sorter($key) {
    return function ($a, $b) use ($key) {
        return strnatcmp($a[$key], $b[$key]);
    };
}

usort($array, build_sorter('key_b'));