method_exists
Note that before PHP 5.3.3, this function fails for private properties in base classes (which is fixed in 5.3.3)
<?php
class Base {
private $var = 1;
public function test() {
var_dump( property_exists( $this, 'var' ) );
}
}
class Derived extends Base {
}
$b = new Base();
$b->test();
$d = new Derived();
$d->test();
?>
Executing this code with PHP 5.0 <= x < 5.3 this script echoes (incorrect result):
bool(true)
bool(false)
Executing this code with PHP 5.3 this script echoes (correct result):
bool(true)
bool(true)
property_exists
(PHP 5 >= 5.1.0)
property_exists — Checks if the object or class has a property
Descrierea
This function checks if the given property exists in the specified class.
Notă:
As opposed with isset(), property_exists() returns TRUE even if the property has the value NULL.
Parametri
- class
-
The class name or an object of the class to test for
- property
-
The name of the property
Valorile întoarse
Returns TRUE if the property exists, FALSE if it doesn't exist or NULL in case of an error.
Note
Notă:
Utilizarea acestei funcții va duce la utilizarea oricărui autoîncărcător înregistrat dacă clasa nu este cunoscută deja.
Notă:
The property_exists() function cannot detect properties that are magically accessible using the __get magic method.
Istoria schimbărilor
| Versiunea | Descriere |
|---|---|
| 5.3.0 | This function checks the existence of a property independent of accessibility. |
Exemple
Example #1 A property_exists() example
<?php
class myClass {
public $mine;
private $xpto;
static protected $test;
static function test() {
var_dump(property_exists('myClass', 'xpto')); //true
}
}
var_dump(property_exists('myClass', 'mine')); //true
var_dump(property_exists(new myClass, 'mine')); //true
var_dump(property_exists('myClass', 'xpto')); //true, as of PHP 5.3.0
var_dump(property_exists('myClass', 'bar')); //false
var_dump(property_exists('myClass', 'test')); //true, as of PHP 5.3.0
myClass::test();
?>
add a note
User Contributed Notes
property_exists
foddex at foddex dot net
22-Dec-2010 01:56
webmaster at thedigitalorchard dot ca
24-Apr-2010 09:56
According to my tests, isset() is 4 times faster than property_exists(), so use a combination of these functions in your programming for best performance.
For example:
<?php
$fld = 'somevar';
if (isset($this->$fld) || property_exists($this, $fld)) {
}
?>
If your programming routinely checks a larger number of property names that are expected to exist, whereas a smaller number may not, then using isset(), as above, will result in faster execution of the programming.
peter at nonumber dot nl
27-Aug-2008 02:48
The above PHP4 function did not work for me. This does:
<?php
if ( !function_exists( 'property_exists' ) ) {
function property_exists( $class, $property ) {
if ( is_object( $class ) ) {
$vars = get_object_vars( $class );
} else {
$vars = get_class_vars( $class );
}
return array_key_exists( $property, $vars );
}
}
?>
rayro at gmx dot de
11-Nov-2007 04:49
To check the existance of a property from outside the scope (even if it's not accessible) try/consider the following:
<?php
function property_exists_safe($class, $prop)
{
$r = property_exists($class, $prop);
if (!$r) {
$x = new ReflectionClass($class);
$r = $x->hasProperty($prop);
}
return $r;
}
class myClass {
public $mine;
private $xpto;
static function test1() {
// true, it can be accessed from here
var_dump(property_exists('myClass', 'xpto'));
}
static function test2() {
// true, it can be accessed from everywhere!
var_dump(property_exists_safe('myClass', 'xpto'));
}
}
var_dump(property_exists('myClass', 'mine')); //true
var_dump(property_exists(new myClass, 'mine')); //true
var_dump(property_exists('myClass', 'xpto')); //false, isn't public
myClass::test1();
echo("\n");
var_dump(property_exists_safe('myClass', 'mine')); //true
var_dump(property_exists_safe(new myClass, 'mine')); //true
var_dump(property_exists_safe('myClass', 'xpto')); //true
myClass::test2(); //true
?>
bool(true)
bool(true)
bool(false)
bool(true)
bool(true)
bool(true)
bool(true)
bool(true)
caist at caist dot com
14-Oct-2007 06:19
A niet way to copy properties from one object to another avoiding stuff like:
$obj2 -> prop1 = $obj1 -> prop1;
$obj2 -> prop2 = $obj1 -> prop2;
$obj2 -> prop3 = $obj1 -> prop3;
...is this loop through all properties:
// copies all property values from obj1 to obj2
foreach ($obj1 as $prop_name => $prop_value)
{
if (property_exists(get_class($obj2), $prop_name))
$obj2 -> {$prop_name} = $prop_value;
}
K
13-Jul-2007 01:11
to ssettl2 at google's mail >
1) Use self:: in static methods : http://php.net/language.oop5.static
2) Under the description title of this page : "This function checks if the given property exists in the specified class (and if it is ACCESSIBLE FROM THE CURRENT SCOPE)."
This is normal behaviour in PHP5.
Regards
Alan71
07-Aug-2006 10:57
This function is case-sensitive, so :
<?php
class Test {
public $property;
public foo() { echo($property); }
}
property_exists('Test', 'property'); // will return true
property_exists('Test', 'Property'); // will return false
?>
(under PHP5.1.2)
jcaplan at bogus dot amazon dot com
08-Jun-2006 02:35
The documentation leaves out the important case of new properties you add to objects at run time. In fact, property_exists will return true if you ask it about such properties.
<?
class Y {}
$y = new Y;
echo isset( $y->prop ) ? "yes\n" : "no\n"; // no;
echo property_exists( 'Y', 'prop' ) ? "yes\n" : "no\n"; // no
echo property_exists( $y, 'prop' ) ? "yes\n" : "no\n"; // no
$y->prop = null;
echo isset( $y->prop ) ? "yes\n" : "no\n"; // no;
echo property_exists( 'Y', 'prop' ) ? "yes\n" : "no\n"; // no
echo property_exists( $y, 'prop' ) ? "yes\n" : "no\n"; // yes
?>
Pete W
01-Jun-2006 11:52
In a similar vein to the previous note, To check in PHP4 if an object has a property, even if the property is null:
<?php
if(array_key_exists('propertyName',get_object_vars($myObj)))
{
// ..the property has been defined
}
?>
timshel
14-Nov-2005 04:20
I haven't tested this with the exact function semantics of 5.1, but this code should implement this function in php < 5.1:
<?php
if (!function_exists('property_exists')) {
function property_exists($class, $property) {
if (is_object($class))
$class = get_class($class);
return array_key_exists($property, get_class_vars($class));
}
}
?>