Symfony2 Form with Doctrine Relationship Persistence Issue - doctrine-orm

Question

So I have 3 entities with their properties.
A USER which has MANY USERSKILLS with each ONE having a single corresponding SKILL
Here are the entities:
/**
* #ORM\Table(name="skills")
* #ORM\Entity()
*/
class Skill
{
/**
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #ORM\Column(name="name", type="string", length=30, unique=true)
*/
private $name;
/**
* #ORM\Column(name="active", type="boolean")
* #var bool
*/
private $active = false;
/**
* #ORM\OneToMany(targetEntity="UserSkill", mappedBy="skill")
*/
private $userSkills;
}
/**
* #ORM\Table(name="user_skill")
* #ORM\Entity()
*/
class UserSkill
{
/**
* #ORM\Id
* #ORM\ManyToOne(targetEntity="User", inversedBy="skills")
* #var User
*/
private $user;
/**
* #ORM\Id
* #ORM\ManyToOne(targetEntity="Skill", inversedBy="userSkills")
* #var Skill
*/
private $skill;
/**
* #ORM\Column(type="integer")
* #var int
*/
private $level = 0;
}
/**
* StartupDriven\UserBundle\Entity\User
*
* #ORM\Table(name="users")
* #ORM\Entity(repositoryClass="StartupDriven\UserBundle\Entity\UserRepository")
*/
class User implements AdvancedUserInterface, \Serializable
{
/**
* #ORM\OneToMany(targetEntity="UserSkill", mappedBy="user")
* #var ArrayCollection
*/
private $skills;
}
They are created using 2 symfony form objects which works fantastically.
The problem is when I go to persist these objects in the controller.... I get an error
$form->handleRequest($request);
if ($form->isValid()) {
/**
* #var User $user
*/
$user = $form->getData();
/**
* #var UserSkill $userSkill
*/
foreach ($user->getSkills() as $userSkill) {
// No updating skills... Only new ones.
if (!$userSkill->getId()) {
// Check skill name match.
if ($matched_skill = $em->getRepository('StartupDrivenUserBundle:Skill')->findOneBy(array('name' => $userSkill->getName()))) {
$userSkill->setSkill($matched_skill);
}
else {
// No match. Create new generic skill.
$em->persist($userSkill->getSkill());
// THE ERROR HAPPENS ON THE FOLLOWING LINE!
$em->flush();
}
// Set the User
$userSkill->setUser($user);
// Persist the user skill.
$em->persist($userSkill);
$em->flush();
}
}
$em->persist($user);
$em->flush();
Error Message:
A new entity was found through the relationship 'StartupDriven\UserBundle\Entity\User#skills' that was not configured to cascade persist operations for entity: StartupDriven\UserBundle\Entity\UserSkill#0000000053e8628e00007f7f2fd56e1f. To solve this issue: Either explicitly call EntityManager#persist() on this unknown entity or configure cascade persist this association in the mapping for example #ManyToOne(..,cascade={"persist"}). If you cannot find out which entity causes the problem implement 'StartupDriven\UserBundle\Entity\UserSkill#__toString()' to get a clue.
I have tried every combination of persist & flush that I can think of. I have tried the cascade option above (which gives a different error that the "user id which is required by the primary key rules is not set")... I am completely lost. It seems like such a simple relationship... Where am I going wrong?