events.md

#Events

Admin bundle provide several events that can be handled in application. List of available events can be found in AdminEvents and ResourceEvents. Listeners of CRUD_LIST_* events will receive one argument of FSi\Bundle\AdminBundle\Event\ListEvent class. Listeners of all the other events will receive one argument of FSi\Bundle\AdminBundle\Event\FormEvent class.

Following example will show you how to handle dynamically added/removed relation elements for doctrine entity. Just like in http://symfony.com/doc/current/cookbook/form/form_collections.html#allowing-tags-to-be-removed

This exsmple is only proof of concept, you should use orphanRemoval doctrine relation option instead of building complicated event listener.

First you need to create event listener class

<?php

namespace FSi\Bundle\DemoBundle\EventListener;

use FSi\Bundle\DemoBundle\Entity\News;
use FSi\Bundle\DemoBundle\Entity\Tag;
use FSi\Bundle\AdminBundle\Event\FormEvent;
use Symfony\Bridge\Doctrine\ManagerRegistry;

class CRUDEventListener
{
    /**
     * @var \Symfony\Bridge\Doctrine\ManagerRegistry
     */
    protected $registry;

    /**
     * @var array
     */
    protected $tags;

    /**
     * @param ManagerRegistry $registry
     */
    public function __construct(ManagerRegistry $registry)
    {
        $this->tags = array();
        $this->registry = $registry;
    }

    /**
     * @param \FSi\Bundle\AdminBundle\Event\FormEvent $event
     */
    public function crudEditEntityPreSubmit(FormEvent $event)
    {
        $entity = $event->getForm()->getData();

        if ($entity instanceof News) {
            $this->tags[$entity->getId()] = array();

            foreach ($entity->getTags() as $tag) {
                $this->tags[$entity->getId()][] = $tag;
            }
        }
    }

    /**
     * @param \FSi\Bundle\AdminBundle\Event\FormEvent $event
     */
    public function crudEditEntityPostSave(FormEvent $event)
    {
        $entity = $event->getForm()->getData();

        if ($entity instanceof News) {
            foreach ($entity->getTags() as $tag) {
                foreach ($this->tags[$entity->getId()] as $key => $toDel) {
                    if ($toDel->getId() === $tag->getId()) {
                        unset($this->tags[$entity->getId()][$key]);
                    }
                }
            }

            foreach ($this->tags[$entity->getId()] as $tag) {
                $this->registry->getManager()->remove($tag);
                $this->registry->getManager()->flush();
            }
        }
    }
}

Next and last step is event listener registration

<!-- src/FSi/Bundle/DemoBundle/Resources/config/services.xml --> 

<?xml version="1.0" ?>

<container xmlns="http://symfony.com/schema/dic/services"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">

    <services>
        <!-- Event Listeners -->
        <service id="fsi_demo_bundle.admin.listener.crud" class="FSi\Bundle\DemoBundle\EventListener\CRUDEventListener">
            <argument type="service" id="doctrine" />
            <tag name="kernel.event_listener" event="admin.crud.edit.form.request.pre_submit" method="crudEditEntityPreSubmit" />
            <tag name="kernel.event_listener" event="admin.crud.edit.entity.post_save" method="crudEditEntityPostSave" />
        </service>
    </services>
</container>