Doctrine: Retrieving entities that may not be saved to the database yet - symfony

Question

I'm parsing a big XML file, with many items. Each item has many categories, which can repeat. Here's a sample XML.
<item>
<category>Category1</category>
<category>Category2</category>
<category>Category3</category>
<category>Category4</category>
<category>Category5</category>
</item>
<item>
<category>Category1</category>
<category>Category2</category>
<category>Category3</category>
<category>Category7</category>
<category>Category9</category>
</item>
Using doctrine to handle the many-to-many relationship described above, I have a sample code like this:
$em = $this->getDoctrine()->getEntityManager();
foreach ($items as $item) {
[...]
$categories = ... //Array with category names, parsed from the XML.
foreach ($categories as $category) {
//This will check if the 'item' entity
//already has a category with that name.
$exists = $entity->getCategories()->exists(function($key, $element) use ($category) {
return $category == $element->getName();
});
if (!$exists) {
//If there's already one on the database, we'll load it.
//Otherwise, we'll save a new Category..
$query = $this->_entityManager->createQueryBuilder();
$query->select('c')
->from("MyBundle:Category, 'c');
->where("c.name = :name")
->setParameter("name", $category);
}
$result = $query->getQuery()->getOneOrNullResult();
if ($result != null) {
$item->addCategory($result);
} else {
$categoryEntity = new Category($category);
$em->persist($categoryEntity);
$item->addCategory($categoryEntity);
}
}
}
}
The thing is: I only flush() the entitymanager when I complete looping through all items. Therefore, $query->getQuery()->getOneOrNullResult() always returns null, leading me to create duplicated categories.
In the XML example above, I have the following:
| item |
| 1 |
| 2 |
| category.id, category.name |
| 1, Category1 |
| 2, Category2 |
| 3, Category3 |
| 4, Category4 |
| 5, Category5 |
| 6, Category1 |
| 7, Category2 |
| 8, Category3 |
| 9, Category7 |
| 10, Category9 |
| item | category |
| 1 | 1 |
| 1 | 2 |
| 1 | 3 |
| 1 | 4 |
| 1 | 5 |
| 2 | 6 |
| 2 | 7 |
| 2 | 8 |
| 2 | 9 |
| 2 | 10 |
I wanted the following:
| item |
| 1 |
| 2 |
| category.id, category.name |
| 1, Category1 |
| 2, Category2 |
| 3, Category3 |
| 4, Category4 |
| 5, Category5 |
| 6, Category7 |
| 7, Category9 |
| item | category |
| 1 | 1 |
| 1 | 2 |
| 1 | 3 |
| 1 | 4 |
| 1 | 5 |
| 2 | 1 |
| 2 | 2 |
| 2 | 3 |
| 2 | 9 |
| 2 | 10 |
Simply adding $em->flush() after $em->persist($categoryEntity) solves it, but I don't want to flush things just yet (or for that matter, flush only a category). There are a lot of unfinished stuff to do and I don't want to interrupt my transaction. I want to still be able to rollback to the very beginning and exclude all unused categories, if I need to (and, obviously, without running additional queries).
My question is: is there a way to access both the database and doctrine's internal entity mapping to retrieve an entity that might or might not have an ID? Or will I have to create this mapping myself, run a DQL and check on my mapping?

Answer 1

Doctrine2 can't do this for you,
but it's pretty easy to store the newly created categories in your loop and check them when you get a MISS from the database.
$_created_categories = array();
if (!$exists) {
// If there's already one on the database, we'll load it.
// Otherwise, we'll save a new Category..
$query = $this->_entityManager->createQueryBuilder();
$query->select('c')
->from("MyBundle:Category, 'c');
->where("c.name = :name")
->setParameter("name", $category);
$result = $query->getQuery()->getOneOrNullResult();
if ($result) {
$item->addCategory($result);
elseif ( isset($_created_categories[$category]) ) {
$item->addCategory($_created_categories[$category]);
} else {
$categoryEntity = new Category($category);
$em->persist($categoryEntity);
$item->addCategory($categoryEntity);
$_created_categories[$category] = $categoryEntity;
}
}
There is no memory overhead to store the new categories entities in the $_created_categories array as all objects are manipuled by reference in PHP.