Symfony - manyToMany not getting saved - php

Question

The Scenario
I have two Entities linked together with manyToMany relation.
Entities
User
Interest
So on a user's profile form there is a field called Interests which is rendered using select2.
Now a user can select as many Interests as they want and upon saving doctrine is doing the nice job of saving the selected Interests in the linked table. When I reload the profile page I can see that interests that I already selected.
The Problem
Although the form field is linked with an Interest entity
$form->add('interest', EntityType::class, array(
'class' => 'AppBundle\Entity\Interest',
'multiple' => true,
'expanded' => false,
'by_reference' => false)
A user can also add interests of their own which do not exist in Interest table with the help of Tagging Support on front end and on backend to save this information I have Form Event Subscriber in place that checks if any of the Interests submitted by the user does not exist in Interest table add them and it is here where I get the following exception
Message
This value is not valid.
Origin
interest
Cause
Symfony\Component\Validator\ConstraintViolation
Object(Symfony\Component\Form\Form).children[interest] = [0 => 1, 1 => 4, 2 => 7, 3 => www]
Caused by:
Symfony\Component\Form\Exception\TransformationFailedException
Unable to reverse value for property path "interest": Could not find all matching choices for the given values
Caused by:
Symfony\Component\Form\Exception\TransformationFailedException
Could not find all matching choices for the given values
Here is the Event Subscriber code
namespace AppBundle\Form\EventListener;
use AppBundle\Entity\Interest;
use Doctrine\ORM\EntityManager;
use Symfony\Component\Form\FormEvent;
use Symfony\Component\Form\FormEvents;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\Security\Core\Authorization\AuthorizationChecker;
class AddProfileFieldSubscriber implements EventSubscriberInterface
{
protected $authorizationChecker;
protected $em;
function __construct(AuthorizationChecker $authorizationChecker, EntityManager $em)
{
$this->authorizationChecker = $authorizationChecker;
$this->em = $em;
}
public static function getSubscribedEvents()
{
// Tells the dispatcher that you want to listen on the form.pre_set_data
// event and that the preSetData method should be called.
return array(
FormEvents::PRE_SUBMIT => 'onPreSubmit'
);
}
/**
* #param FormEvent $event
*/
public function onPreSubmit(FormEvent $event){
$interestTags = $event->getData();
$interestTags = $interestTags['interest'];
foreach($interestTags as $interestTag){
$interest = $this->em->getRepository('AppBundle:Interest')->findOneBy(array('id' => $interestTag));
if(!$interest){
$newInterest = new Interest();
$newInterest->setName($interestTag);
$this->em->persist($newInterest);
$this->em->flush();
}
}
}
}
The Attempt
I updated the form code to as following by adding choice_value
$form->add('interest', EntityType::class, array(
'class' => 'AppBundle\Entity\Interest',
'multiple' => true,
'expanded' => false,
'by_reference' => false,
'choice_value' => 'name'
)
);
and I changed the query inside the Event Subscriber from
$interest = $this->em->getRepository('AppBundle:Interest')->findOneBy(array('id' => $interestTag));
to
$interest = $this->em->getRepository('AppBundle:Interest')->findOneBy(array('name' => $interestTag));
This worked perfectly at first but when I reload the profile page my interest field appears empty
The reason why it appears empty is because (my assumption) of id="select2-user_interest-result-5z18-Education" I think that needs to look something like id="select2-user_interest-result-5z18-66"
<ul class="select2-results__options" role="tree" aria-multiselectable="true" id="select2-user_interest-results"
aria-expanded="true" aria-hidden="false">
<li class="select2-results__option" id="select2-user_interest-result-5z18-Education" role="treeitem"
aria-selected="false">Education
</li>
<li class="select2-results__option" id="select2-user_interest-result-rdka-History" role="treeitem"
aria-selected="false">History
</li>
<li class="select2-results__option select2-results__option--highlighted"
id="select2-user_interest-result-lfq4-Architecture" role="treeitem" aria-selected="false">Architecture
</li>
<li class="select2-results__option" id="select2-user_interest-result-qqiq-Entrepreneurship" role="treeitem"
aria-selected="false">Entrepreneurship
</li>
<li class="select2-results__option" id="select2-user_interest-result-qutx-Technology" role="treeitem"
aria-selected="false">Technology
</li>
<li class="select2-results__option" id="select2-user_interest-result-sfx4-Engineering" role="treeitem"
aria-selected="false">Engineering
</li>
I crossed check the data in Interest table and I can see the new interests added by the user which did not exist before, so its working but on front end its not being displayed. Out of curiosity i removed the choice_value and then reloaded the profile page and I could see the new interests
I will really appreciate if anything can push me in right direction and let me know what am I missing and how can i get this to work.

Answer 1

You can't do that as EntityType extend ChoiceType which doesn't allow adding new values in the choice list.
You should use CollectionType like in the cookbook http://symfony.com/doc/current/cookbook/form/form_collections.html
To make a proper select in your code, you'll also have to insert in the view, along with your form, the full list of all interests.
Then your view should looks like :
<select name='{{ form.interest.vars.full_name }}' id="{{ form.interest.vars.id }}" class='select2'>
{% for interestList as interestItem %}
<option value='{{ interestItem.id }}' {% if some_logic_to_check_whether_the_item_is_selected %}selected='selected'{% endif %} >{{ interestItem.name }}</option>
{% endfor %}
</select>