property_exists
(PHP 5 >= 5.1.0, PHP 7, PHP 8)
property_exists — オブジェクトもしくはクラスにプロパティが存在するかどうかを調べる
説明
この関数は、与えられたプロパティ property が
指定されたクラスに存在するかどうかを確認します。
注意:
isset() とは対照的に、 プロパティの値が
nullの場合でも property_exists() はtrueを返します。
パラメータ
object_or_class-
確認するクラス名、もしくはクラスのオブジェクトを指定します。
property-
プロパティ名を指定します。
例
例1 property_exists() の例
<?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
var_dump(property_exists('myClass', 'bar')); //false
var_dump(property_exists('myClass', 'test')); //true
myClass::test();
?>注意
注意:
この関数を使うと、未知のクラスに対しては登録済みの autoloader を使用します。
注意:
property_exists() 関数は、マジックメソッド
__getを使ってアクセスするプロパティを検出することはできません。
＋add a note
User Contributed Notes 6 notes
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()
Stefan W ¶
11 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
?>
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
$s->setAge(10); //Undefined Property
?>
ewisuri [gmail] ¶
10 years ago
As of PHP 5.3.0, calling property_exists from a parent class sees private properties in sub-classes.
<?php
class P {
public function test_prop($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
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)
biziclop ¶
1 year 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.
*/
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