Unable to save (A new entity was found through the relationship) - doctrine

Question

Error Message:
"A new entity was found through the relationship
'AppBundle\Entity\Category#products' that was not configured to
cascade persist operations for entity:
AppBundle\Entity\Product#00000000133d712400000000104ed306. 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
'AppBundle\Entity\Product#__toString()' to get a clue."
/AppBundle/Entity/Product
class Product
{
/**
* #ORM\Column(type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #ORM\Column(type="string", length=100)
*/
private $name;
/**
* #ORM\Column(type="decimal", scale=2)
*/
private $price;
/**
* #ORM\Column(type="text")
*/
private $description;
/**
* #ORM\ManyToOne(targetEntity="Category", inversedBy="products")
* #ORM\JoinColumn(name="category_id", referencedColumnName="id")
*/
private $category;
/**
* Get id
*
* #return integer
*/
public function getId()
{
return $this->id;
}
/**
* Set name
*
* #param string $name
*
* #return Product
*/
public function setName($name)
{
$this->name = $name;
return $this;
}
/**
* Get name
*
* #return string
*/
public function getName()
{
return $this->name;
}
/**
* Set price
*
* #param string $price
*
* #return Product
*/
public function setPrice($price)
{
$this->price = $price;
return $this;
}
/**
* Get price
*
* #return string
*/
public function getPrice()
{
return $this->price;
}
/**
* Set description
*
* #param string $description
*
* #return Product
*/
public function setDescription($description)
{
$this->description = $description;
return $this;
}
/**
* Get description
*
* #return string
*/
public function getDescription()
{
return $this->description;
}
/**
* Set category
*
* #param \AppBundle\Entity\Category $category
*
* #return Product
*/
public function setCategory(\AppBundle\Entity\Category $category = null)
{
$this->category = $category;
return $this;
}
/**
* Get category
*
* #return \AppBundle\Entity\Category
*/
public function getCategory()
{
return $this->category;
}
}
/AppBundle/Entity/Category
class Category
{
/**
* #var int
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #var string
*
* #ORM\Column(name="name", type="string", length=255)
*/
protected $name;
/**
* #ORM\OneToMany(targetEntity="Product", mappedBy="category")
*/
protected $products;
public function __construct()
{
$this->products = new ArrayCollection();
}
/**
* Get id
*
* #return int
*/
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 product
*
* #param \AppBundle\Entity\Product $product
*
* #return Category
*/
public function addProduct(\AppBundle\Entity\Product $product)
{
$this->products[] = $product;
return $this;
}
/**
* Remove product
*
* #param \AppBundle\Entity\Product $product
*/
public function removeProduct(\AppBundle\Entity\Product $product)
{
$this->products->removeElement($product);
}
/**
* Get products
*
* #return \Doctrine\Common\Collections\Collection
*/
public function getProducts()
{
return $this->products;
}
}
/AppBundle/Form/CategoryType
class CategoryType extends AbstractType
{
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder->add('name');
$builder->add('products', CollectionType::class, array(
'entry_type' => ProductType::class
));
}
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(array(
'data_class' => 'AppBundle\Entity\Category'
));
}
public function getName()
{
return 'category';
}
}
/AppBundle/Form/ProductType
class ProductType extends AbstractType
{
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder->add('name')
->add('price')
->add('description');
}
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(array(
'data_class' => 'AppBundle\Entity\Product',
));
}
public function getName()
{
return 'app_bundle_product_type';
}
}
/AppBundle/Controller/CategoryController
class CategoryController extends Controller
{
/**
* #Route("/category/new", name="category_new")
*
*/
public function newAction(Request $request)
{
$category = new Category();
$product = new Product();
$category->getProducts()->add($product);
$form = $this->createForm(CategoryType::class, $category);
$form->handleRequest($request);
if ($form->isValid() && $form->isSubmitted()) {
$em = $this->getDoctrine()->getManager();
$em->persist($category);
$em->flush();
}
return $this->render('category/new.html.twig', array(
'form' => $form->createView(),
));
}
}
/category/new.html.twig
{% extends 'base.html.twig' %}
{% block body %}
{{ form_start(form) }}
{{ form_widget(form) }}
<button type="submit" class="btn btn-primary">Save</button>
{{ form_end(form) }}
{% endblock %}

Answer 1

You should change association in order to tell doctrine to persist all new category products
...
/**
* #ORM\OneToMany(targetEntity="Product", mappedBy="category", cascade={"persist", "remove"})
*/
protected $products;
...
or persist it manually
...
$em->persist($category);
$em->persist($product);
$em->flush();
...
Also set category for product
...
$product = new Product();
$product->setCategory($category);
...