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PHP - Manual: get_object_vars

2024-11-15

get_object_vars

(PHP 4, PHP 5, PHP 7, PHP 8)

get_object_vars — 返回由对象属性组成的关联数组

说明

get_object_vars(object $obj): array

返回由 obj 指定的对象中定义的属性组成的关联数组。

注意:

在 PHP 4.2.0 之前的版本中，如果在 obj 对象实例中声明的变量没有被赋值，则它们将不会在返回的数组中。而在 PHP 4.2.0 之后，这些变量作为键名将被赋予 null 值。

示例 #1 使用 get_object_vars()

<?php
class Point2D {
    var $x, $y;
    var $label;

    function Point2D($x, $y)
    {
        $this->x = $x;
        $this->y = $y;
    }

    function setLabel($label)
    {
        $this->label = $label;
    }

    function getPoint()
    {
        return array("x" => $this->x,
                     "y" => $this->y,
                     "label" => $this->label);
    }
}

// "$label" is declared but not defined
$p1 = new Point2D(1.233, 3.445);
print_r(get_object_vars($p1));

$p1->setLabel("point #1");
print_r(get_object_vars($p1));

?>

以上例程会输出：

 Array
 (
     [x] => 1.233
     [y] => 3.445
     [label] =>
 )

 Array
 (
     [x] => 1.233
     [y] => 3.445
     [label] => point #1
 )

参见 get_class_methods() 和 get_class_vars()。

参数

object

An object instance.

返回值

Returns an associative array of defined object accessible non-static properties for the specified object in scope. If a property have not been assigned a value, it will be returned with a null value.

更新日志

版本 说明
5.3.0 This function now returns NULL if the object isn't an object.
prior to 5.3.0 If the object isn't an object, then get_object_vars() would return false
prior to 4.2.0 If the variables declared in the class of which the object is an instance, have not been assigned a value, those will not be returned in the array

范例

示例 #2 Use of get_object_vars()

<?php

class foo {
    private $a;
    public $b = 1;
    public $c;
    private $d;
    static $e;
   
    public function test() {
        var_dump(get_object_vars($this));
    }
}

$test = new foo;
var_dump(get_object_vars($test));

$test->test();

?>

以上例程会输出：

array(2) {
  ["b"]=>
  int(1)
  ["c"]=>
  NULL
}
array(4) {
  ["a"]=>
  NULL
  ["b"]=>
  int(1)
  ["c"]=>
  NULL
  ["d"]=>
  NULL
}

参见

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User Contributed Notes 4 notes

up
50
fmmarzoa at librexpresion dot org
17 years ago
You can still cast the object to an array to get all its members and see its visibility. Example:

<?php

class Potatoe {
    public $skin;
    protected $meat;
    private $roots;

    function __construct ( $s, $m, $r ) {
        $this->skin = $s;
        $this->meat = $m;
        $this->roots = $r;
    }
}

$Obj = new Potatoe ( 1, 2, 3 );

echo "<pre>\n";
echo "Using get_object_vars:\n";

$vars = get_object_vars ( $Obj );
print_r ( $vars );

echo "\n\nUsing array cast:\n";

$Arr = (array)$Obj;
print_r ( $Arr );

?>

This will returns:

Using get_object_vars:
Array
(
    [skin] => 1
)

Using array cast:
Array
(
    [skin] => 1
    [ * meat] => 2
    [ Potatoe roots] => 3
)

As you can see, you can obtain the visibility for each member from this cast. That which seems to be spaces into array keys are '\0' characters, so the general rule to parse keys seems to be:

Public members: member_name
Protected memebers: \0*\0member_name
Private members: \0Class_name\0member_name

I've wroten a obj2array function that creates entries without visibility for each key, so you can handle them into the array as it were within the object:

<?php

function obj2array ( &$Instance ) {
    $clone = (array) $Instance;
    $rtn = array ();
    $rtn['___SOURCE_KEYS_'] = $clone;

    while ( list ($key, $value) = each ($clone) ) {
        $aux = explode ("\0", $key);
        $newkey = $aux[count($aux)-1];
        $rtn[$newkey] = &$rtn['___SOURCE_KEYS_'][$key];
    }

    return $rtn;
}

?>

I've created also a <i>bless</i> function that works similar to Perl's bless, so you can further recast the array converting it in an object of an specific class:

<?php

function bless ( &$Instance, $Class ) {
    if ( ! (is_array ($Instance) ) ) {
        return NULL;
    }

    // First get source keys if available
    if ( isset ($Instance['___SOURCE_KEYS_'])) {
        $Instance = $Instance['___SOURCE_KEYS_'];
    }

    // Get serialization data from array
    $serdata = serialize ( $Instance );

    list ($array_params, $array_elems) = explode ('{', $serdata, 2);
    list ($array_tag, $array_count) = explode (':', $array_params, 3 );
    $serdata = "O:".strlen ($Class).":\"$Class\":$array_count:{".$array_elems;

    $Instance = unserialize ( $serdata );
    return $Instance;
}
?>

With these ones you can do things like:

<?php

define("SFCMS_DIR", dirname(__FILE__)."/..");
require_once (SFCMS_DIR."/Misc/bless.php");

class Potatoe {
    public $skin;
    protected $meat;
    private $roots;

    function __construct ( $s, $m, $r ) {
        $this->skin = $s;
        $this->meat = $m;
        $this->roots = $r;
    }

    function PrintAll () {
        echo "skin = ".$this->skin."\n";
        echo "meat = ".$this->meat."\n";
        echo "roots = ".$this->roots."\n";
    }
}

$Obj = new Potatoe ( 1, 2, 3 );

echo "<pre>\n";
echo "Using get_object_vars:\n";

$vars = get_object_vars ( $Obj );
print_r ( $vars );

echo "\n\nUsing obj2array func:\n";

$Arr = obj2array($Obj);
print_r ( $Arr );

echo "\n\nSetting all members to 0.\n";
$Arr['skin']=0;
$Arr['meat']=0;
$Arr['roots']=0;

echo "Converting the array into an instance of the original class.\n";
bless ( $Arr, Potatoe );

if ( is_object ($Arr) ) {
    echo "\$Arr is now an object.\n";
    if ( $Arr instanceof Potatoe ) {
        echo "\$Arr is an instance of Potatoe class.\n";
    }
}

$Arr->PrintAll();

?>
up
7
niemans at pbsolo dot nl
1 year ago
You can use an anonymous class to return public variables from inside the class:

public function getPublicVars () {
    $me = new class {
        function getPublicVars($object) {
            return get_object_vars($object);
        }
    };
    return $me->getPublicVars($this);
}

Test script:

class Test {
    protected $protected;
    public    $public;
    private   $private;
    public function getAllVars () {
        return call_user_func('get_object_vars', $this);
    }
    public function getPublicVars () {
        $me = new class {
            function getPublicVars($object) {
                return get_object_vars($object);
            }
        };
        return $me->getPublicVars($this);
    }
}

$test = new Test();
print_r(get_object_vars($test)); // array("public" => NULL)
print_r($test->getAllVars());   // array("protected" => NULL, "public" => NULL, "private" => NULL)
print_r($test->getPublicVars()); // array("public" => NULL)
up
3
Fabien Haddadi
10 years ago
It seems like there's no function that determines all the *static* variables of a class.

I've come out with this one as I needed it in a project:

<?php
function get_class_static_vars($object) {
     return array_diff(get_class_vars(get_class($object)), get_object_vars($object));
}
?>

It relies on an interesting property: the fact that get_object_vars only returns the non-static variables of an object.
up
2
marcus at marcusball dot me
1 year ago
When dealing with a very large quantity of objects, it is worth noting that using `get_object_vars()` may drastically increase memory usage.

If instantiated objects only use predefined properties from a class then PHP can use a single hashtable for the class properties, and small memory-efficient arrays for the object properties:

If a class is defined with three properties ($foo, $bar, and $baz), "PHP no longer has to store the data in a hashtable, but instead can say that $foo is proprety 0, $bar is proprety 1, $baz is property 2 and then just store the properties in a three-element C array. This means that PHP only needs one hashtable in the class that does the property-name to offset mapping and uses a memory-efficient C-array in the individual objects."

However, if you call `get_object_vars()` on an object like this, then PHP WILL build a hashtable for the individual object. If you have a large quantity of objects, and you call `get_object_vars()` on all of them, then a hashtable will be built for each object, resulting in a lot more memory usage. This can be seen in this bug report: https://bugs.php.net/bug.php?id=79392

The effects of this can be seen in this example:

<?php
class Example {
    public $foo;
    public $bar;
    public $baz;
}

function printMem($label) {
    $usage = memory_get_usage();
    echo sprintf('%s: %d (%.2f MB)', $label, $usage, $usage / 1000000) . PHP_EOL;
}

printMem('start');

$objects = [];
for ($i = 0; $i < 20000; $i++) {
    $obj = new Example;
    $obj->foo = bin2hex(random_bytes(5));
    $obj->bar = bin2hex(random_bytes(5));
    $obj->baz = bin2hex(random_bytes(5));
    $objects[] = $obj;
}

printMem('before get_object_vars');

// Clone each object, and get the vars on the clone
foreach ($objects as $obj) {
    $c = clone $obj;
    $vars = get_object_vars($c);

    // Accessing and modifying the original object is fine.
    foreach ($vars as $var => $val) {
        $obj->{$var} = strrev($val);
    }
}

printMem('get_object_vars using clone');

// Get the vars on each object directly
foreach ($objects as $obj) {
    $vars = get_object_vars($obj);

    // The memory is used even if you do not modify the object.
}

printMem('get_object_vars direct access');
?>

The output of this is:

    start: 405704 (0.41 MB)
    before get_object_vars: 6512416 (6.51 MB)
    get_object_vars using clone: 6033408 (6.03 MB)
    get_object_vars direct access: 13553408 (13.55 MB)

In short, if you are using classes to avoid additional memory usage associated with hashtables (like in associative arrays), be aware that `get_object_vars()` will create a hashtable for any object passed to it.

This appears to be present in all versions of PHP; I've tested it on PHP 5, 7, and 8.

Quotes are from Nikic's blog posts on arrays and hashtable memory usage, and Github gist "Why objects (usually) use less memory than arrays in PHP".
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官方地址：https://www.php.net/manual/en/function.get-object-vars.php

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