Updating (from the inverse side) bidirectional many-to-many relationships in Doctrine 2?

Question

Customer is the inverse side of \"keywords/customers\" relationship with Keyword:

/**
 * @ORM         


        

Answer 1

Ok, found the way, even if I'm not fully satisfied. The key was this example form collection field type. Basically what's happening with my previous form definition was:

$customer->getKeywords() = $postData; // $postData is somewhere in form framework

And that is just an assignment of a collection (of selected keywords) to customer keywords. No method were invoked on Keyword instances (owning side). The key option is by_reference (for me it's just a bad name, but anyways...):

$form
    ->add($this->factory->createNamed('entity', 'keywords', null, array(
        // ...
        'by_reference' => false
    ))
);

This way the form framework is going to call the setter, that is $customer->setKeywords(Collection $keywords). In that method, you can "tell" the owning side to store your association:

public function setKeywords(Collection $keywords)
{
    foreach($keywords as $keyword) {
        $keyword->addCustomer($this); // Owning side call!
    }

    $this->keywords = $keywords;

    return $this;
}

(Always check for duplicate instances on the owning side, using contains method).

At this point, only checked keywords will be added ($keyword argument). There is the need to manage removal of unchecked keywords (controller side):

$originalKeywords = $customer->getKeywords()->toArray(); // When GET or POST

// When POST and form valid
$checkedKeywords = $customer->getKeywords()->toArray(); // Thanks to setKeywords

// Loop over all keywords
foreach($originalKeywords as $keyword) {
    if(!in_array($keyword, $checkedKeywords)) { // Keyword has been unchecked
        $keyword->removeCustomer($customer);
        $manager->persist($keyword);
    }
}

Ugly, but works. I would have the code for removal moved to the Customer class, but it's not possible at all. If you'll find a better solution, let me know!