PHP check whether property exists in object or class
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
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
}
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
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';