Forms - Managing OneToMany collection elements - doctrine-orm

Question

Let's imagine these 2 entities:
ShoppingCart
creationDate
Item
name
shoppingCart # ManyToOne
I'm managing a ShoppingCart in a form with a CollectionType of Items
public function buildForm(FormBuilderInterface $builder, array $options)
{
// ...
$builder
// ...
->add('items', CollectionType::class, array(
'entry_type' => ItemFormType::class,
// ...
}
I'd like my users to be able to add/remove items, which seems to me like a quite common need.
If I understand well, here is what I have to do:
Define the reverse OneToMany side of the ShoppingCart relation to Item
Make sure this relation have the cascade={"persist"} and orphanRemoval=true options
Initialize this items Collection into the constructor
Set the allow_add and allow_delete form option to true
Set the by_reference form option to false
Make sure andItem() & removeItem() functions are implemented into ShoppingCart
Set/unset the owning side relation to the ShoppingCart in addition to add/remove the Item from the ShoppingCart items collection
Keep the collection indexes within javascript so Doctrine can keep track of references
Am I forgetting something ?
I find it a big pain in the arse for me compared to the need and to other frameworks/ORMs
Is there a way to do it simpler ?

Answer 1

As I understand, your question is "why is it so complicated", isn't it?
Well, it's not. You've listed things multiple layers in your project. To exaggerate the point a little bit - why didn't you wrote that in order to create this form you need to install Symfony or even turn on your computer. ;-)
Anyway, most of these things are not required, others should be done before anyway.
Let's start with your OneToMany relation (Doctrine level).
ShoppingCart is your aggregate root (DDD term, but it doesn't matter if you follow DDD idea), which means you probably will do most of work on this object which will handle Items inside. If so, then you should have done inversed side of the relation, which covers these points (I think you went into details so much to make your list longer ;-), they all should be in one list item), but it takes a minute to do this stuff:
Define the reverse OneToMany side of the ShoppingCart relation to Item
Make sure this relation have the cascade={"persist"} and orphanRemoval=true options
Initialize this items Collection into the constructor
Make sure andItem() & removeItem() functions are implemented into ShoppingCart
Set/unset the owning side relation to the ShoppingCart in addition to add/remove the Item from the ShoppingCart items collection
This has nothing to do with forms. It's about how you want your entities to work with Doctrine.
Following two are not required:
Set the allow_add and allow_delete form option to true
Set the by_reference form option to false
They are about enabling/disabling features. You want them, so you need to use them. That's obvious and still not so much to do.
Last one:
Keep the collection indexes within javascript so Doctrine can keep track of references
This is the one that I actually don't understand. But what you need (in your case, because you're using allow_add/delete feature), is to provide JavaScript code that will create HTML for new row or delete existing one. But that's also just about copying prototype code. Also there are ready examples in Symfony's doc.

Answer 2

Let me answer myself in a simpler manner:
No I am not forgetting anything
No we can't do simpler
Some reasons are explained in #dragoste answer