Catchable Fatal Error: Object of class could not be converted to string

Question

I have this Entity defined:

namespace CategoryBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use Gedmo\Mapping\Annotation as Gedmo;

/**
 * @ORM\Entity
 * @ORM\Table(name="category")
 */
class Category {

    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     * 
     */
    protected $id;

    /**
     *
     * @ORM\Column(type="string", length=255, nullable=false)
     */
    protected $name;

    /**
     *
     * @ORM\Column(type="integer", nullable=true)
     */
    protected $parent;

    /**
     *
     * @ORM\Column(type="string", length=255, nullable=true)
     */
    protected $description;

    /**
     *
     * @ORM\Column(type="integer")
     */
    protected $age_limit;

    /**
     * @Gedmo\Timestampable(on="create")
     * @ORM\Column(name="created", type="datetime")
     */
    protected $created;

    /**
     * @Gedmo\Timestampable(on="update")
     * @ORM\Column(name="modified", type="datetime")
     */
    protected $modified;

    public function getId() {
        return $this->id;
    }

    public function setParent(Category $parent = null) {
        $this->parent = $parent;
    }

    public function getParent() {
        return $this->parent;
    }

    public function setName($name) {
        $this->name = $name;
    }

    public function getName() {
        return $this->name;
    }

    public function setDescription($description) {
        $this->description = $description;
    }

    public function getDescription() {
        return $this->description;
    }

    public function setAgeLimit($age_limit) {
        $this->age_limit = $age_limit;
    }

    public function getAgeLimit() {
        return $this->age_limit;
    }

    public function setCreated($created) {
        $this->created = $created;
    }

    public function getCreated() {
        return $this->created;
    }

    public function setModified($modified) {
        $this->modified = $modified;
    }

    public function getModified() {
        return $this->modified;
    }
}

Then I have this method in my controller for handle form submission:

/**
 * Handle category creation
 *
 * @Route("/category/create", name="category_create")
 * @Method("POST")
 * @Template("CategoryBundle:Default:new.html.twig")
 */
public function createAction(Request $request) {
    $entity = new Category();
    $form = $this->createForm(new CategoryType(), $entity);
    $form->handleRequest($request);

    if ($form->isValid()) {
        $em = $this->getDoctrine()->getManager();
        $em->persist($entity);
        $em->flush();

        return $this->redirect($this->generateUrl('category_list'));
    }

    return $this->render('CategoryBundle:Default:new.html.twig', array(
                'entity' => $entity,
                'form' => $form->createView(),
    ));
}

And finally this is my CategoryType.php:

public function buildForm(FormBuilderInterface $builder, array $options) {
    $builder
            ->add('parent', 'entity', array('class' => 'CategoryBundle:Category', 'property' => 'name', 'required' => false))
            ->add('name')
            ->add('description')
            ->add('age_limit');
}

When I try to save data I get this error:

An exception occurred while executing 'INSERT INTO category (name, parent, description, age_limit, created, modified) VALUES (?, ?, ?, ?, ?, ?)' with params ["Cat2", {}, null, 2, "2013-08-06 09:58:03", "2013-08-06 09:58:03"]:

Catchable Fatal Error: Object of class CategoryBundle\Entity\Category could not be converted to string in /var/www/html/vendor/doctrine/dbal/lib/Doctrine/DBAL/Statement.php line 138

What I'm doing wrong? How do I access to the property in my method so I can save the value?

UPDATE

Based on suggestions made by @sybio, I rewrite my Entity so now I have this:

/**
 * @ManyToOne(targetEntity="Category")
 * @JoinColumn(name="parent", referencedColumnName="id")
 */
protected $parent;

Is that right?

Answer 1

Here what I think :

You are trying to save a Category object as parent, but in the following code :

/**
 *
 * @ORM\Column(type="integer", nullable=true)
 */
protected $parent;

You said that a parent is an integer, so the framework try to save the parent category as an integer but to feet it it's probably converting the object as a string before, and so it crashes...

I'm not totally sure, but you should rethink your property "$parent".

It should be a self referencing relation.

Example :

/**
 * @OneToMany(targetEntity="Category", mappedBy="parent")
 */
private $children;

/**
 * @ManyToOne(targetEntity="Category", inversedBy="children")
 * @JoinColumn(name="parent_id", referencedColumnName="id")
 */
protected $parent;

public function __construct() {
    $this->children = new \Doctrine\Common\Collections\ArrayCollection();
}

Don't forget to refactor your getter / setter :

    /**
     * Set parent
     *
     * @param \CategoryBundle\Entity\Category $parent
     */
    public function setParent(\CategoryBundle\Entity\Category $parent = null)
    {
        $this->parent = $parent;
    }

    /**
     * Get parent
     *
     * @return \CategoryBundle\Entity\Category 
     */
    public function getParent()
    {
        return $this->parent;
    }

Hope this is the solution !