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;
$ob->b = 2;
In JS, I can write this to check if variable a exists in an object:
if ('a' in ob)
In PHP, can anything like this be done?
if (property_exists($ob, 'a'))
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($foo->bar)); // false
empty() is a better solution? !empty($var) ?
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.
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 $person->middleName ?? 'Person does not have a middle name';
?:) does NOT check if the property exists! And ?? is the null coalescing operator.
?:.?: on this page, since the title explicitly says: PHP check whether property exists in object or classTo check if something exits, you can use the PHP function isset() see php.net. This function will check if the variable is set and is not NULL.
Example:
if(isset($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', $property)) {
//do something
}
If you want to know if a property exists in an instance of a class that you have defined, simply combine property_exists() with isset().
public function hasProperty($property)
{
return property_exists($this, $property) && isset($this->$property);
}
property_exists($this, $property) is kind of redundant here, since your code will always have the same result as isset($this->$property) alone.
isset() cannot tell you if a property is a true member of the class definition. I will look up again later to make sure.__get() and more importantly __isset() magic methods, the output will be different in some cases.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.
$ob is defined/null or not in this case. It has nothing to do with the property itself.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
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
