Cloning embedded document only works if value is changed - mongodb

Question

I have a Mongo database to which I am connected through the following document classes in Symfony, using Doctrine ODM (I am only showing the relevant properties).
/**
* #MongoDB\Document
* #MongoDB\InheritanceType("COLLECTION_PER_CLASS")
*/
class Feature {
/** #MongoDB\EmbedOne(targetDocument="FeatureProperties") */
protected $properties;
}
/** #MongoDB\Document */
class City extends Feature {}
/** #MongoDB\EmbeddedDocument */
class FeatureProperties {
/** #MongoDB\String */
protected $name;
}
I am trying to clone a City in my controller, including its properties, essentially its properties.name.
To do this, I get the city using QueryBuilder and call it $city_origin.
Then, here's how I clone it:
$new_city = clone $city_origin;
$city_name = $city_origin->getProperties()->getName();
// $city_name .= ' ';
$documentManager->detach($city_origin);
$new_city->setId('_' . $city_origin->getId());
$new_city->getProperties()->setName($city_name);
$documentManager->persist($new_city);
$documentManager->flush();
The new document is created, but properties and properties.name do not exist.
Now the strange thing is, if I uncomment the line where I modify the $city_name, then the properties.name is created with the modified value.
If instead of fetching the $city_name from $city_origin I input its value manually (as a string), the attribute is not created either. If I give the name of another City in my collection, there is no issue.
Ideally, I would like to clone the entire document with its embedded documents: how can I do that?

Answer 1

When you clone a object, you get a copy of this object whit the same reference of the embedded object.
When you do :
$documentManager->detach($city_origin);
Doctrine will detach all the object related to $city_origin because of your entity definition :
cascade=DETACH or cascade=ALL
http://docs.doctrine-project.org/en/2.0.x/reference/working-with-objects.html#detaching-entities
You need to define the clone function in the city class and clone all the object you need.
http://www.php.net/manual/en/language.oop5.cloning.php