Php exist object property

property_exists

Функция проверяет, существует ли атрибут property в указанном классе.

Замечание:

В противоположность isset() , property_exists() возвращает TRUE даже если свойство имеет значение NULL .

Список параметров

Имя класса или объекта класса для проверки

Возвращаемые значения

Возвращает TRUE , если свойство существует, FALSE — если оно не существует или NULL в случае ошибки.

Примечания

Замечание:

Вызов этой функции будет использовать все зарегистрированные функции автозагрузки, если класс еще не известен.

Замечание:

Функция property_exists() не определяет магически доступные свойства с помощью метода __get.

Список изменений

Версия	Описание
5.3.0	Эта функция проверяет существование свойства вне зависимости от его доступности.

Примеры

Пример #1 Пример использования property_exists()

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, начиная с версии PHP 5.3.0
var_dump ( property_exists ( ‘myClass’ , ‘bar’ )); //false
var_dump ( property_exists ( ‘myClass’ , ‘test’ )); //true, начиная с версии PHP 5.3.0
myClass :: test ();

Смотрите также

Источник

How to Check for Property Existence in PHP: Methods and Best Practices

Learn how to check if an object or class has a particular property in PHP using property_exists() and isset() methods. Explore best practices and tips for efficient property existence checks.

• Using the property_exists() method
• Using the isset() function
• Checking for class constants
• Checking object properties in JavaScript
• Best practices and tips for checking property existence
• Other quick PHP code examples for checking object property existence
• Conclusion
• How to check if a property exists in a PHP object?
• How to check if an object or class has a property?
• How to check if a variable is set or not PHP?
• What does hasOwnProperty check in JavaScript?

As a developer, it is essential to check whether an object or class has a particular property in PHP. There are several methods to do this, including the property_exists() and isset() functions. In this blog post, we will explore these methods and provide helpful tips and best practices for checking property existence in PHP.

Using the property_exists() method

The property_exists() method is used to check if an object or class has a particular property. This method takes two parameters: the object or class to be checked, and the name of the property. If the property exists, the method returns true. Otherwise, it returns false. It is important to note that the property_exists() method will return true even if the property has a null value.

Here is an example of how to use the property_exists() method:

class MyClass < public $myProperty; >$obj = new MyClass(); $result = property_exists($obj, 'myProperty'); if ($result) < echo 'Property exists'; >else

Using the isset() function

The isset() function can also be used to check whether a variable, including an object property, exists or not. This function returns true if the variable exists and is not null, and false otherwise.

Here is an example of how to use the isset() function:

class MyClass < public $myProperty; >$obj = new MyClass(); if (isset($obj->myProperty)) < echo 'Property exists'; >else

Checking for class constants

The property_exists() and isset() methods cannot be used to check for class constants. Instead, the defined() function can be used to check for the existence of a class constant.

Here is an example of how to use the defined() function:

class MyClass < const MY_CONSTANT = 'value'; >if (defined('MyClass::MY_CONSTANT')) < echo 'Constant exists'; >else

Checking object properties in JavaScript

In JavaScript, there are several ways to check if an object has a property . One way is to use the in operator to check if the property exists in the object’s prototype chain. Another way is to use the hasOwnProperty() method to check if the property exists in the object itself.

Here is an example of how to use the in operator and hasOwnProperty() method:

var obj = < myProperty: 'value' >;if ('myProperty' in obj) < console.log('Property exists'); >else < console.log('Property does not exist'); >if (obj.hasOwnProperty('myProperty')) < console.log('Property exists in object'); >else

Best practices and tips for checking property existence

1. Always double-check property names to avoid typos.
2. Use object-oriented programming principles to organize code and make it easier to work with objects and properties.
3. Use a cheatsheet for quick reference to PHP functions.
4. Consider the advantages and disadvantages of using the property_exists() and isset() methods, including their limitations in checking for class constants.
5. Use the hasOwnProperty() method in JavaScript to check if an object has its own property.

Other quick PHP code examples for checking object property existence

In Php , for instance, php check if object has attribute code sample

if(property_exists($car,color))< //$car->color exists >

property_exists( $object , "key1" ); // bool

In Php , php check if class exists code example

In Php , check if object has method php code example

In Php , for instance, php check if stdclass object has property code example

if(property_exists($sale, "gpps"))

Conclusion

Checking if an object or class has a particular property is an essential task in PHP and JavaScript. The property_exists() and isset() methods can be used in PHP, while the in operator and hasOwnProperty() method can be used in JavaScript. By following best practices and tips, developers can efficiently and effectively check property existence in their code.

Frequently Asked Questions — FAQs

What is the difference between property_exists() and isset() in PHP?

The property_exists() method checks if an object or class has a particular property, even if the property is null. The isset() function checks if a variable, including an object property, exists and is not null.

Can I use property_exists() and isset() for class constants in PHP?

How can I check for property existence in JavaScript?

In JavaScript, you can use the in operator to check if a property exists in the object’s prototype chain. You can also use the hasOwnProperty() method to check if the property exists in the object itself.

What are the best practices for checking property existence in PHP?

Double-check property names to avoid typos, use object-oriented programming principles to organize code, and use a cheatsheet for quick reference to PHP functions.

How can I efficiently and effectively check property existence in my code?

Consider the advantages and disadvantages of different methods, including their limitations in checking for class constants. Use the hasOwnProperty() method in JavaScript to check if an object has its own property.

Why is checking for property existence important in PHP and JavaScript?

Checking if an object or class has a particular property is an essential task in PHP and JavaScript as it helps to ensure the smooth functioning of the code and avoid runtime errors.

Источник

property_exists

This function checks if the given property exists in the specified class.

Note:

As opposed with isset() , property_exists() returns true even if the property has the value null .

Parameters

The class name or an object of the class to test for

Return Values

Returns true if the property exists, false if it doesn’t exist or null in case of an error.

Examples

Example #1 A property_exists() example

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 ();

Notes

Note:

Using this function will use any registered autoloaders if the class is not already known.

Note:

The property_exists() function cannot detect properties that are magically accessible using the __get magic method.

See Also

Источник