PHP check whether property exists in object or class
PhpClassVariablesObjectParametersPhp Problem Overview
I understand PHP does not have a pure object variable, but I want to check whether a property is in the given object or class.
$ob = (object) array('a' => 1, 'b' => 12);
or
$ob = new stdClass;
$ob->a = 1;
$ob->b = 2;
In JS, I can write this to check if variable a
exists in an object:
if ('a' in ob)
In PHP, can anything like this be done?
Php Solutions
Solution 1 - Php
property_exists( mixed $class , string $property )
if (property_exists($ob, 'a'))
isset( mixed $var [, mixed $... ] )
NOTE : Mind that isset() will return false if property is null
if (isset($ob->a))
Example 1:
$ob->a = null
var_dump(isset($ob->a)); // false
Example 2:
class Foo
{
public $bar = null;
}
$foo = new Foo();
var_dump(property_exists($foo, 'bar')); // true
var_dump(isset($foo->bar)); // false
Solution 2 - Php
To check if the property exists and if it's null too, you can use the function property_exists()
.
Docs: http://php.net/manual/en/function.property-exists.php
As opposed with isset(), property_exists() returns TRUE even if the property has the value NULL.
>bool property_exists ( mixed $class , string $property )
Example:
if (property_exists($testObject, $property)) {
//do something
}
Solution 3 - Php
Neither isset or property_exists work for me.
- isset returns false if the property exists but is NULL.
- property_exists returns true if the property is part of the object's class definition, even if it has been unset.
I ended up going with:
$exists = array_key_exists($property, get_object_vars($obj));
Example:
class Foo {
public $bar;
function __construct() {
$property = 'bar';
isset($this->$property); // FALSE
property_exists($this, $property); // TRUE
array_key_exists($property, get_object_vars($this)); // TRUE
unset($this->$property);
isset($this->$property); // FALSE
property_exists($this, $property); // TRUE
array_key_exists($property, get_object_vars($this)); // FALSE
$this->$property = 'baz';
isset($this->$property); // TRUE
property_exists($this, $property); // TRUE
array_key_exists($property, get_object_vars($this)); // TRUE
}
}
Solution 4 - Php
Solution
echo $person->middleName ?? 'Person does not have a middle name';
To show how this would look in an if statement for more clarity on how this is working.
if($person->middleName ?? false) {
echo $person->middleName;
} else {
echo 'Person does not have a middle name';
}
Explanation
The traditional PHP way to check for something's existence is to do:
if(isset($person->middleName)) {
echo $person->middleName;
} else {
echo 'Person does not have a middle name';
}
OR for a more class specific way:
if(property_exists($person, 'middleName')) {
echo $person->middleName;
} else {
echo 'Person does not have a middle name';
}
These are both fine in long form statements but in ternary statements they become unnecessarily cumbersome like so:
isset($person->middleName) ? echo $person->middleName : echo 'Person does not have a middle name';
You can also achieve this with just the ternary operator like so:
echo $person->middleName ?: 'Person does not have a middle name';
But... if the value does not exist (is not set) it will raise an E_NOTICE
and is not best practise. If the value is null
it will not raise the exception.
Therefore ternary operator to the rescue making this a neat little answer:
echo $person->middleName ?? 'Person does not have a middle name';
Solution 5 - Php
If you want to know if a property exists in an instance of a class that you have defined, simply combine property_exists()
with isset()
.
public function hasProperty($property)
{
return property_exists($this, $property) && isset($this->$property);
}
Solution 6 - Php
Usually I use kind of custom helper
/**
* @param Object $object
* @param string $property as a string with nested properties 'prop1.nesterdProp.deepvalue'
* @param mixed $default
* @return mixed
*/
function getPropertyOrDefault(Object $object, string $property, $default = null)
{
$value = $object;
$path = explode('.', $property);
foreach ($path as $prop) {
if (is_object($value) && property_exists($value, $prop)) {
$value = $value->{$prop};
} else {
return $default;
}
}
return $value;
}
Keep in mind that if property is empty you will get empty value and no default value.
BTW the similar helper works in JS as well.
Solution 7 - Php
To check if something exits, you can use the PHP function isset() see php.net. This function will check if the variable is set and is not NULL.
Example:
if(isset($obj->a))
{
//do something
}
If you need to check if a property exists in a class, then you can use the build in function property_exists()
Example:
if (property_exists('class', $property)) {
//do something
}
Solution 8 - Php
Using array_key_exists() on objects is Deprecated in php 7.4
Instead either isset() or property_exists() should be used
reference : php.net
Solution 9 - Php
Just putting my 2 cents here.
Given the following class:
class Foo
{
private $data;
public function __construct(array $data)
{
$this->data = $data;
}
public function __get($name)
{
return $data[$name];
}
public function __isset($name)
{
return array_key_exists($name, $this->data);
}
}
the following will happen:
$foo = new Foo(['key' => 'value', 'bar' => null]);
var_dump(property_exists($foo, 'key')); // false
var_dump(isset($foo->key)); // true
var_dump(property_exists($foo, 'bar')); // false
var_dump(isset($foo->bar)); // true, although $data['bar'] == null
Hope this will help anyone