Doctrine2: calling flush multiple times - php

Question

I have a question concerning Doctrine and entities on Symfony 2.3.
According to the v2.3 "Documentation Book" chapter "Databases and Doctrine" > Saving Related Entities, the example create simultaneously a new row in both product and category tables and associates product.category_id value with the id of the new category item.
The problem is that the controller action creates a new Product and a new Category anytime it is invoked!
In order to just create a new product and associate its category_id with an existing category id, this is the routing.yml route:
acme_store_create_product_by_category:
path: /create/newproduct/{name}/{categoryId}
defaults: { _controller: AcmeStoreBundle:Default:createProduct }
I made a test passing parameters via URL:
/web/store/create/newproduct/Kayak/12
I did something like this which seems working fine:
public function createProductAction($name, $categoryId)
{
$em = $this->getDoctrine()->getManager();
if ( $em->getRepository("AcmeStoreBundle:Category")->findOneById($categoryId) ) {
$product = new Product();
$product->setName($name);
$product->setPrice(220);
$product->setDescription("This is just a test");
$em->persist($product);
$em->flush();
$newproduct = $em->getRepository("AcmeStoreBundle:Product")->find($product->getId());
/** Create new product and populate $newproduct with its data */
$repository = $em->getRepository("AcmeStoreBundle:Category")->find($categoryId);
$newproduct->setCategory($repository);
$em->persist($newproduct);
$em->flush();
/** Update the id_category field of the new product with parameter $categoryId */
//exit(\Doctrine\Common\Util\Debug::dump($product));
return new Response('Create product ' . $name . ' with category id ' . $categoryId);
} else {
return new Response('It doesn\'t exists any category with id ' . $categoryId);
}
}
My doubt in this case is: Is it a good practice to invoke flush() method two times in the same action ? In this case I would like to create a new product selecting the related category from a "list box".
Thank you in advance!

Answer 1

I think it mostly depends on your application domain. If you run flush two times it means you're running two transactions. In the first one you're persisting a product, in the second one a category. So if the first transaction fails (let's say you have a unique key on the product name and you're trying to persist a product with the same name so you get a duplicate key exception) then ask yourself if it's OK to go on and persist a category. I don't think we can answer that easily here because I think it depends on your application logic, what that endpoint is supposed to do, what happens if you end up having a product and not a category or vice-versa.
You should also consider that if you get an exception during the first transaction your code won't handle that error and the second transaction will therefore fail. When an exception like a duplicate key occurs all entities are detached and the entity manager doesn't know anymore how to manage things. So you'll have to reset it or you're going to get an EntityManager is closed issue.
try {
// first transaction
$entityManager->persist($entityOne);
$entityManager->flush();
} catch (\Exception $e) {
/* ... handle the exception */
$entityManager->resetManager();
}
// now we can safely run a second transaction here
I hope this answers your question :-)

Answer 2

I suggest the edited code snippet.
public function createProductAction($name, $categoryId)
{
$em = $this->getDoctrine()->getManager();
if ( $em->getRepository("AcmeStoreBundle:Category")->findOneById($categoryId) ) {
$repository = $em->getRepository("AcmeStoreBundle:Category")->find($categoryId);
$product = new Product();
$product->setName($name);
$product->setPrice(220);
$product->setDescription("This is just a test");
$product->setCategory($repository);
$em->persist($product);
$em->flush();
return new Response('Create product ' . $name . ' with category id ' . $categoryId);
} else {
return new Response('It doesn\'t exists any category with id ' . $categoryId);
}
}