PHP check whether property exists in object or class

Source: PHP check whether property exists in object or class

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?

---

property_exists( mixed $class , string $property )

if (property_exists($ob, 'a')) 

isset( mixed $var [, mixed $… ] )

if (isset($ob->a))

isset() will return false if property is null

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 in PHP 7

Null Coalescing Operator:

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';