[FLOW3-general] Integrity constraint violation

[Georg Ortner]

Hi I have a persistence question:

I have a model Category. A Category should be able to save references to 
it's child categories. Technically it does the same things like a post 
saving references to related posts in the Blog tutorial:

/**
  *
  * @param \SplObjectStorage<\F3\MyPackage\Domain\Model\Category>
  * @return void
  */
public function setSubCategories(\SplObjectStorage $subCategories) {
	$this->subCategories = clone $subCategories;
}

As long as I do it this way it works just fine, but if I want a method 
which just adds one child like this:

/**
  * @param \F3\MyPackage\Domain\Model\Category $category
  * @return void
  */
public function addSubCategory(\F3\MyPackage\Domain\Model\Category 
$category) {
	$this->subCategories->attach( clone $category );
}

I'm getting this exception when the persistence backend tries to persist 
a Category:

#23000: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate 
entry 'f40627ea-9452-4381-aa53-48f541051120' for key 1 (More information)

PDOException thrown in file
Packages/Framework/FLOW3/Classes/Persistence/Backend/GenericPdo/Backend.php 
in line 179.


So what's the difference? And how in general can I save just a reference 
to an Object of the same type as it self?