Db persistance for dynamic collection in symfony - php

Question

When symfony collection fields are dynamicly added/removed in DOM with javascript, on save of this collection either validation or persisted collection elem ids get messed up. For example if I have Entity\User.php releation like:
/**
* #var \TestBundle\Entity\UserFollowers
*
* #ORM\OneToMany(targetEntity="TestBundle\Entity\UserFollowers", mappedBy="user", cascade={"persist"}, orphanRemoval=true)
* #Assert\Valid()
*/
protected $user_followers;
and backward Entity\UserFollower.php relation like:
/**
* #ORM\ManyToOne(targetEntity="TestBundle\Entity\User", inversedBy="user_followers")
* #ORM\JoinColumn(name="user_id", referencedColumnName="id")
*/
protected $user;
/**
* #var string
* #ORM\Column(name="name", type="string")
* #Assert\NotBlank()
*/
private $name;
And UserFormType like:
$builder->add('user_followers', CollectionType::class, array(
'entry_type' => UserFollowersType::class,
'allow_add' => true,
'allow_delete' => true,
'prototype' => true,
'prototype_name' => '__name__',
'by_reference' => false,
'label' => 'User followers'
))
and UserFollowersFormType like:
public function buildForm(FormBuilderInterface $builder, array $options) {
$builder
->add('name', TextType::class, array(
'attr'=> [
'class' =>'input input-group-field'
],
'label' => false
));
}
when form is handled and user persisted to db either form validation attaches to wrong collection elem or persisted id to db gets wrong, different DOM manipulaiton gets different error, controller is like:
$form->handleRequest($request);
if ($form->isValid()) {
$em->persist($user);
$em->flush();
}
Why is that happening? its like form collection indexes gets messed up....

Answer 1

When you dynamicly add new UserFollowersType form you also have to replace prototype_name __name__ with length of the collection.
On collection init:
var $collection = $(your collection container of forms );
$collection.data('index', $collection.children().length);
var index = $collection.data('index');
//-------on add new form
// Replace '__name__' in the prototype's HTML to
// instead be a number based on how many items we have
var newForm = prototype.replace(prototypeName, index);
// increase the index with one for the next item
$collection.data('index', index + 1);