How to manage collections through an API with symfony2 and forms - rest

Question

I'm building an API where a user can update an entity with a collection as part of it. This works fine if I use forms throughout, but I'm building up the API. My entity looks like this:
<?php
class MyEntity {
// ...
/**
* #ORM\OneToMany(targetEntity="TitleEntity", mappedBy="entityID", cascade={"persist"})
*/
protected $myTitles;
public function getMyTitles() {
return $this->myTitles;
}
public function setMyTitles($titles) {
foreach($titles as $key => $obj) { $obj->setEntity($this); }
$this->myTitles = $collection;
}
public function addMyTitle($obj) {
$obj->setEntity($this);
$this->myTitles[] = $obj;
}
public function removeMyTitle($obj) {
$this->myTitle->removeElement($obj);
}
}
The myTitles is an entity that has an ID, the ID of the entity it is attached to, and then a title.
For the API, I'm passing a JSON content body back as a PUT request for the MyEntity object, so I end up with an array of the titles, and I'm prepping them like this to bind to a form for validation:
$myTitles = array();
foreach($titles as $key => $title) {
$titleObj = new TitleEntity();
$titleObj->setTitle($title);
}
$myEntity->setTitles($titles);
but it complains with:
The form's view data is expected to be of type scalar, array or an instance of
\ArrayAccess, but is an instance of class stdClass. You can avoid this error by
setting the "data_class" option to "stdClass" or by adding a view
transformer that transforms an instance of class stdClass to scalar, array or
an instance of \ArrayAccess
It looks like this happens because I call getMyTitles() before I bind my entity to the form I'm using to validate against.
I'm binding to the form using an array:
$form = $this->createForm(new AddEntity(), $myEntity);
$data = array( // Set all my data );
$form->bind($data);
if($form->isValid() {
// ...
If I do the createForm() call first, and then add the titles afterward, I get this:
Call to a member function removeElement() on a non-object
which occurs inside removeMyTitle().
How do I handle this?
Edit
Here is the AddEntity() type:
<?php
class AddEntity extends AbstractType {
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add('title', 'text')
->add('subheading', 'text')
->add('description', 'textarea')
->add('myTitles', 'collection', array(
'type' => new AddMyTitles(), // Basic type to allow setting the title for myTitle entities
'allow_add' => true,
'allow_delete' => true,
'prototype' => true,
'by_reference' => false,
'options' => array(
'required' => false,
),
));
}
public function getName()
{
return 'addEntity';
}
public function setDefaultOptions(OptionsResolverInterface $resolver)
{
$resolver->setDefaults(array(
'data_class' => 'My\TestBundle\Entity\Entity',
));
}

Answer 1

You need data transformers here.
http://symfony.com/doc/2.0/cookbook/form/data_transformers.html
Basically, you have told the form it is getting an array, and you've given it something else. The transformer is supposed to handle this.
If you need more help I'd need more information.
Also, somewhat bafflingly, you refer to 'myCollections' in your prose but don't show it, in your code.
^^^^^^^^^ fixed by edit.