Symfony: update many-to-many - doctrine-orm

Question

I have Post and Tag entities with many-to-many relationship. In Post create and edit form there is a textbox where I can enter tags separated by comma relevant to that post. For example, when I enter tag1, tag2, tag3 for post with title 'Post1', the form will create post and tag entities and add these tags to tags list of that post.I use data transformer to create tag entities.
class Post{
/**
* #ORM\ManyToMany(targetEntity="Tag", mappedBy="posts",cascade={"all"})
*/
protected $tags;
public function __construct() {
$this->tags = new ArrayCollection();
}
/**
* #return ArrayCollection
*/
public function getTags()
{
return $this->tags;
}
/**
* #param Tag $tag
*/
public function addTag(Tag $tag)
{
$tag->addPost($this);
$this->tags->add($tag);
}
/**
* #param Tag $tag
*/
public function removeTag(Tag $tag)
{
$this->tags->removeElement($tag);
}
}
PostType
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add('title', TextType::class, array('label' => 'Title'))
->add('tags', TextType::class, array('label' => 'Tags'))
;
$builder->get('tags')
->addModelTransformer(new TagViewTransformer($this->manager));
}
TagViewTransformer
class TagViewTransformer implements DataTransformerInterface
{
public function transform($value)
{
/...
}
public function reverseTransform($value)
{
$tags = array();
if ( $value )
{
if( strpos($value, ',') !== false )
{
$list = array_unique(explode(",", $value));
}
else
{
$list = array(trim($value));
}
foreach ( $list AS $tagName )
{
$tag = $this->em
->getRepository('CoreBundle:Tag')
->findOneBy(array('name' => trim($tagName)));
if( !$tag )
{
$tag = new Tag();
$tag->setName(trim($tagName));
$this->em->persist($tag);
}
$tags[] = $tag;
}
}
return $tags;
}
}
This works fine when I try to create Post, all tags are transformed to entities and are added to Post's tags list. but when I try to edit, I start having problems
public function editAction(Request $request, Post $post)
{
$deleteForm = $this->createDeleteForm($post);
$editForm = $this->createForm(PostType::class, $post);
$editForm->handleRequest($request);
$originalTags = $post->getTags();
if ($editForm->isSubmitted() && $editForm->isValid()) {
$em = $this->getDoctrine()->getManager();
$newTags = $editForm->get('tags')->getData();
foreach ($originalTags as $currentTag) {
if (!in_array($currentTag, $newTags)) {
$post->removeTag($currentTag);
}
}
$em->persist($post);
$em->flush();
return $this->redirectToRoute('post_show', array('id' => $post->getId()));
}
return $this->render('AppBundle:Post:edit.html.twig', array(
'entity' => $post,
'form' => $editForm->createView(),
'delete_form' => $deleteForm->createView(),
));
}
Let's say Post has tags: tag1, tag2, tag3, but I want to remove tag3 and add tag4. So I will change tags textbox to tag1, tag2, tag4. However when I submit form, I get tag1, tag2, tag3, tag4. So tag3 is not removed from Post's tag list.
What is wrong with the editAction code?

Answer 1

try with this
public function editAction(Request $request, Post $post)
{
$deleteForm = $this->createDeleteForm($post);
$editForm = $this->createForm(PostType::class, $post);
$editForm->handleRequest($request);
if ($editForm->isSubmitted() && $editForm->isValid()) {
$em = $this->getDoctrine()->getManager();
$em->persist($post);
$em->flush();
return $this->redirectToRoute('post_show', array('id' => $post->getId()));
}
return $this->render('AppBundle:Post:edit.html.twig', array(
'entity' => $post,
'form' => $editForm->createView(),
'delete_form' => $deleteForm->createView(),
));
}

Answer 2

Use Orphan removal to do this :
class Post
{
/**
* #ORM\ManyToMany(targetEntity="Tag", mappedBy="posts", cascade={"all"}, orphanRemoval=true)
*/
protected $tags;
/* Rest of your class */
}
Do some tests, maybe cascade all is not necessary here.