Dynamic Properties Deprecated in PHP 8.2

As of PHP 8.2, creating dynamic properties on most classes is deprecated. Official note: migration82 deprecated features. stdClass still allows dynamic properties; __get/__set usage is unaffected.

What triggers it

Assigning to a property that was never declared on the class (or parent) emits Deprecated: Creation of dynamic property …. Hydrators, ORMs with fuzzy column maps, and “bag” DTOs are frequent sources.

# LEGACY
class Order {}
$o = new Order();
$o->total = 19.99; // deprecated in 8.2+

# MODERN — declare the shape
class Order {
    public float $total;
}
$o = new Order();
$o->total = 19.99;

# TRANSITIONAL — deliberate opt-in (prefer not to sprinkle widely)
#[\AllowDynamicProperties]
class LegacyRow {}

Remediation strategy

• Declare typed properties for known fields (best).
• Use #[\AllowDynamicProperties] only on truly open-ended legacy classes you do not own cleanly.
• Consider WeakMap when attaching metadata to objects you do not control.

Error encyclopedia: Deprecated dynamic property. Scan with deprecated checker. Parent: deprecated features hub.

Related scanners: PHP Version Compatibility Checker · PHP Deprecated Checker.