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Implementing Wakeup or Clone
As explained in the restrictions for entity classes in the manual,
it is usually not allowed for an entity to implement __wakeup
or __clone, because Doctrine makes special use of them.
However, it is quite easy to make use of these methods in a safe
way by guarding the custom wakeup or clone code with an entity
identity check, as demonstrated in the following sections.
Safely implementing __wakeup
To safely implement __wakeup, simply enclose your
implementation code in an identity check as follows:
<?phpclass MyEntity{ private $id; // This is the identifier of the entity. // ... public function __wakeup() { // If the entity has an identity, proceed as normal. if ($this->id) { // ... Your code here as normal ... } // otherwise do nothing, do NOT throw an exception! } // ...}Safely implementing __clone
Safely implementing __clone is pretty much the same:
<?phpclass MyEntity{ private $id; // This is the identifier of the entity. // ... public function __clone() { // If the entity has an identity, proceed as normal. if ($this->id) { // ... Your code here as normal ... } // otherwise do nothing, do NOT throw an exception! } // ...}Summary
As you have seen, it is quite easy to safely make use of
__wakeup and __clone in your entities without adding any
really Doctrine-specific or Doctrine-dependant code.
These implementations are possible and safe because when Doctrine invokes these methods, the entities never have an identity (yet). Furthermore, it is possibly a good idea to check for the identity in your code anyway, since it's rarely the case that you want to unserialize or clone an entity with no identity.