Reading Attributes with the Reflection API
To access attributes from classes, methods, functions, parameters, properties,
and class constants, use the getAttributes() method provided
by the Reflection API. This method returns an array of ReflectionAttribute
instances. These instances can be queried for the attribute name, arguments, and
can be used to instantiate an instance of the represented attribute.
Separating the reflected attribute representation from its actual instance provides more
control over error handling, such as missing attribute classes, mistyped arguments,
or missing values. Objects of the attribute class are instantiated only after calling
ReflectionAttribute::newInstance(), ensuring that argument validation
occurs at that point.
Example #1 Reading Attributes using Reflection API
<?php
#[Attribute]
class MyAttribute
{
public $value;
public function __construct($value)
{
$this->value = $value;
}
}
#[MyAttribute(value: 1234)]
class Thing
{
}
function dumpAttributeData($reflection) {
$attributes = $reflection->getAttributes();
foreach ($attributes as $attribute) {
var_dump($attribute->getName());
var_dump($attribute->getArguments());
var_dump($attribute->newInstance());
}
}
dumpAttributeData(new ReflectionClass(Thing::class));
/*
string(11) "MyAttribute"
array(1) {
["value"]=>
int(1234)
}
object(MyAttribute)#3 (1) {
["value"]=>
int(1234)
}
*/
Instead of iterating over all attributes on the reflection instance,
you can retrieve only those of a specific attribute class by passing
the attribute class name as an argument.
Example #2 Reading Specific Attributes using Reflection API
<?php
function dumpMyAttributeData($reflection) {
$attributes = $reflection->getAttributes(MyAttribute::class);
foreach ($attributes as $attribute) {
var_dump($attribute->getName());
var_dump($attribute->getArguments());
var_dump($attribute->newInstance());
}
}
dumpMyAttributeData(new ReflectionClass(Thing::class));
Hirusha Sharma ¶4 years ago
Fetch properties from functions:
----------------------------------------
Function definition with attributes:
----------------------------------------
#[ReadOnly]
#[Property(type: 'function', name: 'Hello')]
function Hello()
{
return "Hello";
}
-----------------------------------------
Gather attributes from the function
-----------------------------------------
function getAttributes(Reflector $reflection)
{
$attributes = $reflection->getAttributes();
$result = [];
foreach ($attributes as $attribute)
{
$result[$attribute->getName()] = $attribute->getArguments();
}
return $result;
}
$reflection = new ReflectionFunction("Hello");
print_r(getAttributes($reflection));
-----------------------------
OUTPUT
-----------------------------
Array
(
[ReadOnly] => Array
(
)
[Property] => Array
(
[type] => function
[name] => Hello
)
)
