Symfony 2 Entity field type with select and/or add new

Question

Context:

Let there be two entities (correctly mapped for Doctrine).

1. Post with properties {$id (integer, autoinc), $name

Answer 1

My Tag entity has a unique field for the tag name. For add Tags I use a new form type and a transformer.

The Form Type:

namespace Sg\RecipeBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Bridge\Doctrine\RegistryInterface;
use Symfony\Component\Security\Core\SecurityContextInterface;
use Sg\RecipeBundle\Form\DataTransformer\TagsDataTransformer;

class TagType extends AbstractType
{
    /**
     * @var RegistryInterface
     */
    private $registry;

    /**
     * @var SecurityContextInterface
     */
    private $securityContext;


    /**
     * Ctor.
     *
     * @param RegistryInterface        $registry        A RegistryInterface instance
     * @param SecurityContextInterface $securityContext A SecurityContextInterface instance
     */
    public function __construct(RegistryInterface $registry, SecurityContextInterface $securityContext)
    {
        $this->registry = $registry;
        $this->securityContext = $securityContext;
    }

    /**
     * {@inheritdoc}
     */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->addViewTransformer(
            new TagsDataTransformer(
                $this->registry,
                $this->securityContext
            ),
            true
        );
    }

    /**
     * {@inheritdoc}
     */
    public function getParent()
    {
        return 'text';
    }

    /**
     * {@inheritdoc}
     */
    public function getName()
    {
        return 'tag';
    }
}

The Transformer:

em = $registry->getEntityManager();
        $this->securityContext = $securityContext;
    }

    /**
     * Convert string of tags to array.
     *
     * @param string $string
     *
     * @return array
     */
    private function stringToArray($string)
    {
        $tags = explode(',', $string);

        // strip whitespaces from beginning and end of a tag text
        foreach ($tags as &$text) {
            $text = trim($text);
        }

        // removes duplicates
        return array_unique($tags);
    }

    /**
     * Transforms tags entities into string (separated by comma).
     *
     * @param Collection | null $tagCollection A collection of entities or NULL
     *
     * @return string | null An string of tags or NULL
     * @throws UnexpectedTypeException
     */
    public function transform($tagCollection)
    {
        if (null === $tagCollection) {
            return null;
        }

        if (!($tagCollection instanceof Collection)) {
            throw new UnexpectedTypeException($tagCollection, 'Doctrine\Common\Collections\Collection');
        }

        $tags = array();

        /**
         * @var \Sg\RecipeBundle\Entity\Tag $tag
         */
        foreach ($tagCollection as $tag) {
            array_push($tags, $tag->getName());
        }

        return implode(', ', $tags);
    }

    /**
     * Transforms string into tags entities.
     *
     * @param string | null $data Input string data
     *
     * @return Collection | null
     * @throws UnexpectedTypeException
     * @throws AccessDeniedException
     */
    public function reverseTransform($data)
    {
        if (!$this->securityContext->isGranted('ROLE_AUTHOR')) {
            throw new AccessDeniedException('Für das Speichern von Tags ist die Autorenrolle notwendig.');
        }

        $tagCollection = new ArrayCollection();

        if ('' === $data || null === $data) {
            return $tagCollection;
        }

        if (!is_string($data)) {
            throw new UnexpectedTypeException($data, 'string');
        }

        foreach ($this->stringToArray($data) as $name) {

            $tag = $this->em->getRepository('SgRecipeBundle:Tag')
                ->findOneBy(array('name' => $name));

            if (null === $tag) {
                $tag = new Tag();
                $tag->setName($name);

                $this->em->persist($tag);
            }

            $tagCollection->add($tag);

        }

        return $tagCollection;
    }
}

The config.yml

recipe.tags.type:
    class: Sg\RecipeBundle\Form\Type\TagType
    arguments: [@doctrine, @security.context]
    tags:
        - { name: form.type, alias: tag }

use the new Type:

        ->add('tags', 'tag', array(
            'label' => 'Tags',
            'required' => false
            ))

Similarities, like "symfony" and "smfony" can be prevented with an autocomplete function:

TagController:

getRequest();
        $isAjax = $request->isXmlHttpRequest();

        if ($isAjax) {
            $em = $this->getDoctrine()->getManager();

            $search = $request->query->get('term');

            /**
             * @var \Sg\RecipeBundle\Entity\Repositories\TagRepository $repository
             */
            $repository = $em->getRepository('SgRecipeBundle:Tag');

            $qb = $repository->createQueryBuilder('t');
            $qb->select('t.name');
            $qb->add('where', $qb->expr()->like('t.name', ':search'));
            $qb->setMaxResults(5);
            $qb->orderBy('t.name', 'ASC');
            $qb->setParameter('search', '%' . $search . '%');

            $results = $qb->getQuery()->getScalarResult();

            $json = array();
            foreach ($results as $member) {
                $json[] = $member['name'];
            };

            return new Response(json_encode($json));
        }

        return new Response('This is not ajax.', 400);
    }
}

form.html.twig: