Every time I try to send data from form and use doctrine manager I have an error:

As you can see, this problem is according to user_type. I have another entity UserType in which I have this attribute and I want to use it in register form. I have controller and I want to add all form input into database and then error occurs. I would like to point out that I don't want to get and set each attribute manually via for instance:
$name = $form['name']->getData();
$userDetails->setName($name);
Because I think that by using entity manager it is supposed to do automatically like this: UserController.php:
public function register(Request $request){
$user = new User();
$userType = new UserType();
$userDetails = new UserDetails();
$form = $this->createForm(RegisterFormType::class, $user);
$form->handleRequest($request);
if($form->isSubmitted()){
$userDetails = $form->getData();
$em=$this->getDoctrine()->getManager();
$em->persist($userDetails);
$em->flush();
dd($form->getData());
My form in RegisterFormType.php:
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
-> add('name',TextType::class,[
'data_class' => UserDetails::class,
'attr' => [
"placeholder" => 'Name'
],
])
-> add('surname',TextType::class,[
'data_class' => UserDetails::class,
'attr' => [
"placeholder" => 'Surname'
],
])
->add('email',TextType::class,[
'attr' => [
"placeholder" => 'Email'
]
])
->add('password',PasswordType::class,[
'attr' => [
"placeholder" => 'Password'
]
])
->add('confirmPassword',PasswordType::class,[
'attr' => [
"placeholder" => 'Confirm Password'
]
])
/* ->add('user_type',ChoiceType::class, [
'help' => 'Do you want to perform? Choose Artist account type. Do you want to employ artist? Choose Firm.',
'label' => "Account type",
'choices' => [
'None' => 0,
'firm' => 1,
'artist' => 2
],
'attr' => [
"class" => 'choice'
]
])*/
->add('user_type',EntityType::class, [
'class' => UserType::class,
'choice_label'=>'type',
/*'choice_label'=>'type',
'choice_value' => function ($entity) {
return $entity ? $entity->getId() : '';
},*/
])
;
}
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults([
'data_class' => User::class,
]);
}
After submitting input in form I get this data:

The problem is user_type sends as a string I suppose, but should as an object. Am I right?
In User.php
<?php
namespace App\Entity;
use App\Repository\UserRepository;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\ORM\Mapping as ORM;
/**
* @ORM\Entity(repositoryClass=UserRepository::class)
* @ORM\Table(name="`user`")
*/
class User extends UserDetails
{
/**
* @ORM\Id
* @ORM\GeneratedValue(strategy="IDENTITY")
* @ORM\Column(type="integer")
*/
private $id;
/**
* @ORM\Column(type="string", length=255)
*/
private $email;
/**
* @ORM\Column(type="string", length=255)
*/
private $password;
private $confirmPassword;
/**
* @ORM\OneToOne(targetEntity=UserType::class, cascade={"persist", "remove"})
* @ORM\JoinColumn(nullable=false)
*/
private $user_type;
/**
* @ORM\OneToOne(targetEntity=UserDetails::class, cascade={"persist", "remove"})
* @ORM\JoinColumn(nullable=false)
*/
private $user_details;
/**
* @ORM\OneToMany(targetEntity=UserToOffert::class, mappedBy="user_", orphanRemoval=true)
*/
private $user_to_offert;
/**
* @ORM\OneToMany(targetEntity=Skill::class, mappedBy="user_", orphanRemoval=true)
*/
private $skill;
/**
* @ORM\OneToMany(targetEntity=Requirement::class, mappedBy="user_id", orphanRemoval=true)
*/
private $requirement;
public function __construct()
{
$this->user_to_offert = new ArrayCollection();
$this->skill = new ArrayCollection();
$this->requirement = new ArrayCollection();
}
public function getId(): ?int
{
return $this->id;
}
public function getEmail(): ?string
{
return $this->email;
}
public function setEmail(string $email): self
{
$this->email = $email;
return $this;
}
public function getPassword(): ?string
{
return $this->password;
}
public function setPassword(string $password): self
{
$this->password = $password;
return $this;
}
public function getUserType(): ?string
{
return $this->user_type;
}
public function setUserType(string $user_type): self
{
$this->user_type = $user_type;
return $this;
}
public function getUserDetails(): ?UserDetails
{
return $this->user_details;
}
public function setUserDetails(UserDetails $user_details): self
{
$this->user_details = $user_details;
return $this;
}
/**
* @return mixed
*/
public function getConfirmPassword()
{
return $this->confirmPassword;
}
/**
* @param mixed $confirmPassword
*/
public function setConfirmPassword($confirmPassword): void
{
$this->confirmPassword = $confirmPassword;
}
/**
* @return Collection|UserToOffert[]
*/
public function getUserToOffert(): Collection
{
return $this->user_to_offert;
}
public function addUserToOffert(UserToOffert $userToOffert): self
{
if (!$this->user_to_offert->contains($userToOffert)) {
$this->user_to_offert[] = $userToOffert;
$userToOffert->setUser($this);
}
return $this;
}
public function removeUserToOffert(UserToOffert $userToOffert): self
{
if ($this->user_to_offert->removeElement($userToOffert)) {
// set the owning side to null (unless already changed)
if ($userToOffert->getUser() === $this) {
$userToOffert->setUser(null);
}
}
return $this;
}
/**
* @return Collection|Skill[]
*/
public function getSkill(): Collection
{
return $this->skill;
}
public function addSkill(Skill $skill): self
{
if (!$this->skill->contains($skill)) {
$this->skill[] = $skill;
$skill->setUser($this);
}
return $this;
}
public function removeSkill(Skill $skill): self
{
if ($this->skill->removeElement($skill)) {
// set the owning side to null (unless already changed)
if ($skill->getUser() === $this) {
$skill->setUser(null);
}
}
return $this;
}
/**
* @return Collection|Requirement[]
*/
public function getRequirement(): Collection
{
return $this->requirement;
}
public function addRequirement(Requirement $requirement): self
{
if (!$this->requirement->contains($requirement)) {
$this->requirement[] = $requirement;
$requirement->setUser($this);
}
return $this;
}
public function removeRequirement(Requirement $requirement): self
{
if ($this->requirement->removeElement($requirement)) {
// set the owning side to null (unless already changed)
if ($requirement->getUser() === $this) {
$requirement->setUser(null);
}
}
return $this;
}
}
UserDetails.php:
<?php
namespace App\Entity;
use App\Repository\UserDetailsRepository;
use Doctrine\ORM\Mapping as ORM;
/**
* @ORM\Entity(repositoryClass=UserDetailsRepository::class)
*/
class UserDetails
{
/**
* @ORM\Id
* @ORM\GeneratedValue(strategy="IDENTITY")
* @ORM\Column(type="integer")
*/
private $id;
/**
* @ORM\Column(type="string", length=255)
*/
private $name;
/**
* @ORM\Column(type="string", length=255)
*/
private $surname;
/**
* @ORM\Column(type="string", length=255, nullable=true)
*/
private $description;
/**
* @ORM\Column(type="string", length=255, nullable=true)
*/
private $photo;
public function getId(): ?int
{
return $this->id;
}
public function getName(): ?string
{
return $this->name;
}
public function setName(string $name): self
{
$this->name = $name;
return $this;
}
public function getSurname(): ?string
{
return $this->surname;
}
public function setSurname(string $surname): self
{
$this->surname = $surname;
return $this;
}
public function getDescription(): ?string
{
return $this->description;
}
public function setDescription(?string $description): self
{
$this->description = $description;
return $this;
}
public function getPhoto(): ?string
{
return $this->photo;
}
public function setPhoto(?string $photo): self
{
$this->photo = $photo;
return $this;
}
public function __toString() {
return $this->name;
}
}
In UserType.php:
<?php
namespace App\Entity;
/**
* @ORM\Entity(repositoryClass=UserTypeRepository::class)
*/
class UserType
{
/**
* @ORM\Id
* @ORM\GeneratedValue
* @ORM\Column(type="integer")
*/
private $id;
/**
* @ORM\Column(type="string", length=100)
*/
private $type;
public function getId(): ?int
{
return $this->id;
}
public function getType(): ?string
{
return $this->type;
}
public function setType(string $type): self
{
$this->type = $type;
return $this;
}
public function __toString() {
return $this->type;
}
}
If I remove __toString method I get an error:

Any ideas what am I doing wrong? Thank you for your time in advance. Have a nice day!