Symfony2, Doctrine2 Found entity of type Doctrine\Common\Collections\ArrayCollection on association sth#category, but expecting sth

Question

Now I have problem with submitting post data in my form (my forms looks like:

Task: <input text>
Category: <multiple select category>
DueDate: <date>
<submit>

) And after submitting my form, I'll get this error:

Found entity of type Doctrine\Common\Collections\ArrayCollection on association Acme\TaskBundle\Entity\Task#category, but expecting Acme\TaskBundle\Entity\Category

My sources:

Task Object Task.php

<?php

namespace Acme\TaskBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Validator\Constraints as Assert;

/**
 * @ORM\Entity
 * @ORM\Table(name="tasks") 
 */
class Task
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;              

    /**
     * @ORM\Column(type="string", length=200)    
     * @Assert\NotBlank(
     *      message = "Task cannot be empty"      
     * )    
     * @Assert\Length(
     *      min = "3",
     *      minMessage = "Task is too short"         
     * )     
     */     
    protected $task;

    /**
     * @ORM\Column(type="datetime")    
     * @Assert\NotBlank()
     * @Assert\Type("\DateTime")
     */
    protected $dueDate;

    /**
     * @Assert\True(message = "You have to agree")    
     */         
    protected $accepted;

    /**
     * @ORM\ManyToMany(targetEntity="Category", inversedBy="tasks")                       
     */
    protected $category;

    /**
     * Constructor
     */
    public function __construct()
    {
        $this->category = new \Doctrine\Common\Collections\ArrayCollection();
    }

    /**
     * Get id
     *
     * @return integer 
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * Set task
     *
     * @param string $task
     * @return Task
     */
    public function setTask($task)
    {
        $this->task = $task;

        return $this;
    }

    /**
     * Get task
     *
     * @return string 
     */
    public function getTask()
    {
        return $this->task;
    }

    /**
     * Set dueDate
     *
     * @param \DateTime $dueDate
     * @return Task
     */
    public function setDueDate($dueDate)
    {
        $this->dueDate = $dueDate;

        return $this;
    }

    /**
     * Get dueDate
     *
     * @return \DateTime 
     */
    public function getDueDate()
    {
        return $this->dueDate;
    }

    /**
     * Add category
     *
     * @param \Acme\TaskBundle\Entity\Category $category
     * @return Task
     */
    public function addCategory(\Acme\TaskBundle\Entity\Category $category)
    {
        $this->category[] = $category;

        return $this;
    }

    /**
     * Remove category
     *
     * @param \Acme\TaskBundle\Entity\Category $category
     */
    public function removeCategory(\Acme\TaskBundle\Entity\Category $category)
    {
        $this->category->removeElement($category);
    }

    /**
     * Get category
     *
     * @return \Doctrine\Common\Collections\Collection 
     */
    public function getCategory()
    {
        return $this->category;
    }
}

Category Object Category.php

<?php

namespace Acme\TaskBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Validator\Constraints as Assert;

/**
 * @ORM\Entity
 * @ORM\Table(name="categories") 
 */
class Category
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")             
     */
    protected $id; 

    /**
     * @ORM\Column(type="string", length=200, unique=true)   
     * @Assert\NotNull(message="Choose a category", groups = {"adding"})                   
     */         
    protected $name;  

    /**
     * @ORM\ManyToMany(targetEntity="Task", mappedBy="category")
     */
    private $tasks;            


    public function __toString()
    {
        return strval($this->name);
    }
    /**
     * Constructor
     */
    public function __construct()
    {
        $this->tasks = new \Doctrine\Common\Collections\ArrayCollection();
    }

    /**
     * Get id
     *
     * @return integer 
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * Set name
     *
     * @param string $name
     * @return Category
     */
    public function setName($name)
    {
        $this->name = $name;

        return $this;
    }

    /**
     * Get name
     *
     * @return string 
     */
    public function getName()
    {
        return $this->name;
    }

    /**
     * Add tasks
     *
     * @param \Acme\TaskBundle\Entity\Task $tasks
     * @return Category
     */
    public function addTask(\Acme\TaskBundle\Entity\Task $tasks)
    {
        $this->tasks[] = $tasks;

        return $this;
    }

    /**
     * Remove tasks
     *
     * @param \Acme\TaskBundle\Entity\Task $tasks
     */
    public function removeTask(\Acme\TaskBundle\Entity\Task $tasks)
    {
        $this->tasks->removeElement($tasks);
    }

    /**
     * Get tasks
     *
     * @return \Doctrine\Common\Collections\Collection 
     */
    public function getTasks()
    {
        return $this->tasks;
    }
}

TaskType TaskType.php

<?php

namespace Acme\TaskBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;
use Acme\TaskBundle\Form\Type\Category;

class TaskType extends AbstractType
{
    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(array(
            'data_class' => 'Acme\TaskBundle\Entity\Task',
            'cascade_validation' => true,
        ));
    }

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->add('task', 'text', array('label' => 'Task'))
                ->add('dueDate', 'date', array('label' => 'Due Date'))
                ->add('category', new CategoryType(), array('validation_groups' => array('adding')))
                //->add('accepted', 'checkbox')
                ->add('save', 'submit', array('label' => 'Submit'));
    }

    public function getName()
    {
        return 'task';
    }
}

CategoryType CategoryType.php

<?php

namespace Acme\TaskBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;

class CategoryType extends AbstractType
{
    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(array(
            'data_class' => null,
        ));
    }

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->add('name', 'entity', array(
                      'class' => 'AcmeTaskBundle:Category',
                      'query_builder' => function($repository) { return $repository->createQueryBuilder('c')->orderBy('c.id', 'ASC'); },
                      'property' => 'name',
                      'multiple' => true,
                      'label' => 'Categories',
                      ));
    }

    public function getName()
    {
        return 'category';
    }
}

and my Controller DefaultController.php:

public function newAction(Request $request)
{
    $task = new Task();
    $task->setTask('Write name here...');
    $task->setDueDate(new \DateTime('tomorrow'));

    $form = $this->createForm('task', $task);                   
    $form->handleRequest($request);

    if($form->isValid())
    {
        $this->get('session')->getFlashBag()->add(
            'success',
            'Task was successfuly created'
        );
        $em = $this->getDoctrine()->getManager();
        /*
        $category = $this->getDoctrine()->getManager()->getRepository('AcmeTaskBundle:Category')->findOneByName($form->get('category')->getData());
        $task->setCategory($category);
        */
        $em->persist($task);
        try {
            $em->flush();
        } catch (\PDOException $e) {
            // sth
        }

        //$nextAction = $form->get('saveAndAdd')->isClicked() ? 'task_new' : 'task_success';

        //return $this->redirect($this->generateUrl($nextAction));
    } 

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

So, I looked at this problem at the google, but there were different kinds of problems. Any idea?

UPDATE Full error message:

[2013-09-30 14:43:55] request.CRITICAL: Uncaught PHP Exception Doctrine\ORM\ORMException: "Found entity of type Doctrine\Common\Collections\ArrayCollection on association Acme\TaskBundle\Entity\Task#category, but expecting Acme\TaskBundle\Entity\Category" at /var/www/Symfony/vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php line 762 {"exception":"[object] (Doctrine\\ORM\\ORMException: Found entity of type Doctrine\\Common\\Collections\\ArrayCollection on association Acme\\TaskBundle\\Entity\\Task#category, but expecting Acme\\TaskBundle\\Entity\\Category at /var/www/Symfony/vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php:762)"} []

UPDATE 2

My TWIG template new.html.twig

<html>
<head>
<title>Task create</title>
</head>
<body>
{% for flashMessage in app.session.flashbag.get('success') %}
<div style="display: block; padding: 15px; border: 1px solid green; margin: 15px; width: 450px;">
{{ flashMessage }}
</div>
{% endfor %}

{{ form_start(form, {'action': path ('task_new'), 'method': 'POST', 'attr': {'novalidate': 'novalidate' }}) }}
  {{ form_errors(form) }}

  <div>
    {{ form_label(form.task) }}:<br>  
    {{ form_widget(form.task) }} {{ form_errors(form.task) }}<br>
  </div>
  <div>
    {{ form_label(form.category) }}:<br>
    {{ form_widget(form.category) }} {{ form_errors(form.category) }}   
  </div>
  <div>
    {{ form_label(form.dueDate) }}:<br>
    {{ form_widget(form.dueDate) }} {{ form_errors(form.dueDate) }}<br>
  </div>

{{ form_end(form) }}
</body>
</html>

Answer 1

You can improve the controller code by changing your setters in the entities:

In Task:

public function addCategory(Category $category)
{
    if (!$this->categories->contains($category)) {
        $this->categories->add($category);
        $category->addTask($this); // Fix this
    }
}

And in Category:

public function addTask(Task $task)
{
    if (!this->tasks->contains($task)) {
        $this->tasks->add($task);
        $task->addCategory($this);
    }
}

This will keep the elements in the ArrayCollection unique so you won't have to do that checking in your code and will also set the inverse side automatically.