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Implementing Wakeup or Clone

As explained in the restrictions for document classes in the manual. it is usually not allowed for a document 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 a document 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:

1<?php class MyDocument { private $id; // This is the identifier of the document. //... public function __wakeup() { // If the document has an identity, proceed as normal. if ($this->id !== null) { // ... Your code here as normal ... } // otherwise do nothing, do NOT throw an exception! } //... }
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Safely implementing __clone

Safely implementing __clone is pretty much the same:

1<?php class MyDocument { private $id; // This is the identifier of the document. //... public function __clone() { // If the document has an identity, proceed as normal. if ($this->id !== null) { // ... Your code here as normal ... } // otherwise do nothing, do NOT throw an exception! } //... }
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Summary

As you have seen, it is quite easy to safely make use of __wakeup and __clone in your documents without adding any really Doctrine-specific or Doctrine-dependant code.

These implementations are possible and safe because when Doctrine invokes these methods, the documents 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 a document with no identity.