ReflectionClass inspects the definition of a class, rather than running its constructor or calling its methods.
What Is ReflectionClass::getDefaultProperties in PHP?
Returns declared default property values, including non-public defaults, but not uninitialized typed properties.
ReflectionClass::getDefaultProperties()This operation does not accept method arguments.
Example 1: Understanding the Basic Behavior
<?php
class Report { public const VERSION = 2; public string $title = 'Draft'; protected int $pages = 10; public static string $category = 'docs'; public function publish(): void {} }
$reflectionClass = new ReflectionClass(Report::class);
$result = $reflectionClass->getDefaultProperties();
var_dump($result);Output:
array(3) {
["category"]=>
string(4) "docs"
["title"]=>
string(5) "Draft"
["pages"]=>
int(10)
}Explanation: Returns declared default property values, including non-public defaults, but not uninitialized typed properties.
Example 2: Testing Another Case
<?php
interface Exportable { public function export(): string; }
trait HasId { public function getId(): int { return 12; } }
class Invoice implements Exportable { use HasId; public string $name = 'Invoice'; public const STATE = 'open'; public function export(): string { return 'invoice'; } }
$reflectionClass = new ReflectionClass(Invoice::class);
$result = $reflectionClass->getDefaultProperties();
var_dump($result);Output:
array(1) {
["name"]=>
string(7) "Invoice"
}Explanation: Uninitialized typed properties have no default value and may not appear in the resulting array.
Practical Example: Applying the Operation
<?php
abstract class BaseJob { protected string $name = 'job'; abstract public function run(): void; }
class CompletedJob extends BaseJob { public function run(): void {} }
$reflectionClass = new ReflectionClass(CompletedJob::class);
$result = $reflectionClass->getDefaultProperties();
var_dump($result);Output:
array(1) {
["name"]=>
string(3) "job"
}Explanation: The returned metadata may be false, null, an array, or a Reflection object depending on the requested property.
Important Behavior and Edge Cases
- Uninitialized typed properties have no default value and may not appear in the resulting array.
- The returned metadata may be false, null, an array, or a Reflection object depending on the requested property.
Comparison With Related Approaches
| Approach | When to Use It |
|---|---|
ReflectionClass::getDefaultProperties | Returns declared default property values, including non-public defaults, but not uninitialized typed properties. |
ReflectionClass::getProperties() | getDefaultProperties() reports initialized defaults as values; getProperties() returns property metadata descriptors. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Treating metadata returned by ReflectionClass::getDefaultProperties() as though it executes the reflected class member. | Uninitialized typed properties have no default value and may not appear in the resulting array. |
| Choosing ReflectionClass::getProperties() without checking whether it provides the same result. | getDefaultProperties() reports initialized defaults as values; getProperties() returns property metadata descriptors. |
Key Takeaways
- Returns declared default property values, including non-public defaults, but not uninitialized typed properties.
- Uninitialized typed properties have no default value and may not appear in the resulting array.
- The returned metadata may be false, null, an array, or a Reflection object depending on the requested property.
The examples demonstrate where ReflectionClass::getDefaultProperties fits within reflection and metadata. Verify the relevant preconditions whenever you adapt the code to real data.