CascadiaPHP 2024

property_exists

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

property_exists Comprueba si el objeto o la clase tienen una propiedad

Descripción

property_exists(mixed $class, string $property): bool

Esta función comprueba si la propiedad dada por property existe en la clase especificada.

Nota:

A diferencia de isset(), property_exists() devuelve true incluso si la propiedad tiene el valor null.

Parámetros

class

El nombre de la clase o un objeto de la clase a comprobar

property

El nombre de la propiedad

Valores devueltos

Devuelve true si la propiedad existe, false si no existe, o null en caso de error.

Notas

Nota:

Esta función cargará cualquier autocargador registrado si la clase todavía no existe.

Nota:

La función property_exists() no puede detectar propiedades que son accesibles de forma mágica usando el método mágico __get.

Historial de cambios

Versión Descripción
5.3.0 Esta función comprueba la existencia de una propiedad independientemente de su accesibilidad.

Ejemplos

Ejemplo #1 Un ejemplo de property_exists()

<?php

class miClase {
public
$mía;
private
$xpto;
static protected
$prueba;

static function
prueba() {
var_dump(property_exists('miClase', 'xpto')); //true
}
}

var_dump(property_exists('miClase', 'mía')); //true
var_dump(property_exists(new miClase, 'mía')); //true
var_dump(property_exists('miClase', 'xpto')); //true, desde PHP 5.3.0
var_dump(property_exists('miClase', 'bar')); //false
var_dump(property_exists('miClase', 'prueba')); //true, desde PHP 5.3.0
miClase::prueba();

?>

Ver también

add a note

User Contributed Notes 6 notes

up
68
g dot gentile at parentesigraffe dot com
9 years ago
The function behaves differently depending on whether the property has been present in the class declaration, or has been added dynamically, if the variable has been unset()

<?php

class TestClass {

public
$declared = null;

}

$testObject = new TestClass;

var_dump(property_exists("TestClass", "dynamic")); // boolean false, as expected
var_dump(property_exists($testObject, "dynamic")); // boolean false, same as above

$testObject->dynamic = null;
var_dump(property_exists($testObject, "dynamic")); // boolean true

unset($testObject->dynamic);
var_dump(property_exists($testObject, "dynamic")); // boolean false, again.

var_dump(property_exists($testObject, "declared")); // boolean true, as espected

unset($testObject->declared);
var_dump(property_exists($testObject, "declared")); // boolean true, even if has been unset()
up
26
Stefan W
10 years ago
If you are in a namespaced file, and you want to pass the class name as a string, you will have to include the full namespace for the class name - even from inside the same namespace:

<?
namespace MyNS;

class A {
public $foo;
}

property_exists("A", "foo"); // false
property_exists("\\MyNS\\A", "foo"); // true
?>
up
14
Nanhe Kumar
10 years ago
<?php

class Student {

protected
$_name;
protected
$_email;


public function
__call($name, $arguments) {
$action = substr($name, 0, 3);
switch (
$action) {
case
'get':
$property = '_' . strtolower(substr($name, 3));
if(
property_exists($this,$property)){
return
$this->{$property};
}else{
echo
"Undefined Property";
}
break;
case
'set':
$property = '_' . strtolower(substr($name, 3));
if(
property_exists($this,$property)){
$this->{$property} = $arguments[0];
}else{
echo
"Undefined Property";
}

break;
default :
return
FALSE;
}
}

}

$s = new Student();
$s->setName('Nanhe Kumar');
$s->setEmail('nanhe.kumar@gmail.com');
echo
$s->getName(); //Nanhe Kumar
echo $s->getEmail(); // nanhe.kumar@gmail.com
$s->setAge(10); //Undefined Property
?>
up
6
ewisuri [gmail]
10 years ago
As of PHP 5.3.0, calling property_exists from a parent class sees private properties in sub-classes.

<?php
class P {
public function
test_prop($prop) { return property_exists($this, $prop); }
}

class
Child extends P {
private
$prop1;
}

$child = new Child();
var_dump($child->test_prop('prop1')); //true, as of PHP 5.3.0
up
4
saurabh dot agarwal89 at gmail dot com
9 years ago
$a = array('a','b'=>'c');
print_r((object) $a);
var_dump( property_exists((object) $a,'0'));
var_dump( property_exists((object) $a,'b'));

OUTPUT:
stdClass Object
(
[0] => a
[b] => c
)
bool(false)
bool(true)
up
-2
biziclop
8 months ago
I needed a method for finding out if accessing a property outside a class is possible without errors/warnings, considering that the class might use the magic methods __isset/__get to simulate nonexistent properties.

<?php
// returns true if property is safely accessible publicly by using $obj->$prop
// Tested with PHP 5.1 - 8.2, see https://3v4l.org/QBTd1
function public_property_exists( $obj, $prop ){
// allow magic $obj->__isset( $prop ) to execute if exists
if( isset( $obj->$prop )) return true;

// no public/protected/private property exists with this name
if( ! property_exists( $obj, $prop )) return false;

// the property exists, but is it public?
$rp = new ReflectionProperty( $obj, $prop );
return
$rp->isPublic();
}

//// Test/demo
class C {
public
$public = "I’m public!";
protected
$protected = "I’m public!";
private
$private = "I’m public!";
function
__isset( $k ){
return
substr( $k, 0, 5 ) === 'magic';
}
function
__get( $k ){
if(
$k === 'magic_isset_but_null') return null;
return
"I’m {$k}!";
}
}

$o = new C();
foreach( array(
'public', 'protected', 'private',
'magic', 'magic_isset_but_null',
'missing'
) as $prop ){
if(
public_property_exists( $o, $prop ))
echo
"\$o->{$prop} is a public property, its value is: ",
var_export( $o->$prop, true ), "\n";
else echo
"\$o->{$prop} is not a public property.\n";
}
/*
$o->public is a public property, its value is: 'I’m public!'
$o->protected is not a public property.
$o->private is not a public property.
$o->magic is a public property, its value is: 'I’m magic!'
$o->magic_isset_but_null is a public property, its value is: NULL
$o->missing is not a public property.
*/
To Top