Symfony2 Nested forms and ManyToMany relations - symfony

Question

I'm trying to handle a form which is quite complex for me...
We have Collections, which contain books (OneToMany), with articles(OneToMany) and their authors (ManyToMany).
The user can edit a book: he can add or remove an article, and add or remove some authors for each article. There are nested forms : book>article>author.
If the author is new in the Collection, it is created for that Collection.
Entities descriptions look fine, database is generated by the console and seems consistent.
This is working fine if I don't have to deal with authors using the book edition form. If the author exists, I have a duplicate entry bug. If the author is new, I have a "Explicitly persist the new entity or configure cascading persist operations on the relationship" bug.
Here is the code:
public function onSuccess(Book $book)
{
$this->em->persist($book);
foreach($book->getArticles() as $article)
{
$article->setUrlname($this->mu->generateUrlname($article->getName()));
$article->setBook($book);
// Saving (and creating) the authors of the book
foreach ($this->collectionWithAuthors->getAuthors() as $existAuthor){
foreach($article->getAuthors() as $author) {
$authorUrlname=$this->mu->generateUrlname($author->getFirstname().' '.$author->getLastname());
if ( $existAuthor->getUrlname() == $authorUrlname) { // The author is existing
$article->addAuthor($existAuthor);
$this->em->persist($existAuthor);
}else{ // New Author
$newAuthor = new Author();
$newAuthor->setCollection($this->collectionWithBaseArticles);
$newAuthor->setLastname($author->getLastname());
$newAuthor->setFirstname($author->getFirstname());
$newAuthor->setUrlname($authorUrlname);
$this->em->persist($newAuthor);
$article->addAuthor($newAuthor);
}
}
}
$this->em->persist($article);
}
$this->em->flush();
}
I don't know how to use cascades. But the $article->addAuthor() is supposed to call $authors->addArticle():
Article Entity extract
/**
* #ORM\ManyToMany(targetEntity="bnd\myBundle\Entity\Author", mappedBy="articles")
*/
private $authors;
/**
* Add authors
*
* #param bnd\myBundle\Entity\Author $authors
* #return Article
*/
public function addAuthor(\bnd\myBundle\Entity\Author $authors)
{
$this->authors[] = $authors;
$authors->addArticle($this);
}

Answer 1

The logic in foreach statement is wrong. Suppose we have next authors:
Persisted authors (collectionWithAuthors):
John
Eric
Submitted authors
Ada
Eric
So for every existing author (John and Eric) the script loop thru new authors:
foreach ([John, Eric] as $author) {
foreach([Ada, Eric] as $newAuthor) {
// John author: the script persist Ada(right) and Eric(wrong) as new authors
// Eric author: the script persist Ada(wrong), but not Eric(right)
}
}
The solution is to replace article authors with existing authors (if there is similar)
foreach ($article->getAuthors() as $key => $articleAuthor) {
$authorUrlname=$this->mu->generateUrlname($articleAuthor->getFirstname().' '.$articleAuthor->getLastname());
$foundAuthor = false;
// Compare article author with each existing author
foreach ($this->collectionWithAuthors->getAuthors() as $existAuthor) {
if ($existAuthor->getUrlname() == $authorUrlname) {
$foundAuthor = true;
break; // It has found similar author no need to look further
}
}
// Use $existAuthor as found one, otherwise use $articleAuthor
if ($foundAuthor) {
$article->removeAuthor($articleAuthor); // Remove submitted author, so he wont be persisted to database
$article->addAuthor($existAuthor);
} else {
// Here you dont need to create new author
$articleAuthor->setCollection($this->collectionWithBaseArticles);
$articleAuthor->setUrlname($authorUrlname);
}
...
}
$this->_em->persist($article);
You have noticed i removed any author persistent from the loop, to persist these authors its better to set cascade={'persist'} in $authors annotation of Article Entity Class
/**
* #ORM\ManyToMany(targetEntity="Author", cascade={"persist"})
* #ORM\JoinTable(...)
*/
protected $authors;
UPD:
I forgot to mention one thing about cascade persistent. To persist relation betweed article and author you also have to add relation to author entity. Edit the addAuthor() method in the Article entity as below:
public function addAuthor(Author $author)
{
// Only add author relation if the article does not have it already
if (!$this->authors->contains($author)) {
$this->authors[] = $author;
$author->addArticle($this);
}
}
Also, it's a good practice to define default values for a collection of entities in the constructor:
use Doctrine\Common\Collections\ArrayCollection;
// ...
public function __construct()
{
$this->authors = new ArrayCollection();
}