Serializing Entity Relation only to Id with JMS Serializer

Question

I'm trying to serialize a entity relation with JMS Serializer.

Here is the Entity:

class Ad
{ 

    /**
     * @Type("string")
     * @Groups({"manage"})
     * 
     * @var string
     */
    private $description;

    /**
     * @Type("Acme\SearchBundle\Entity\Country")
     * @Groups({"manage"})
     * 
     * @var \Acme\SearchBundle\Entity\Country
     */
    private $country;

    /**
     * @Type("string")
     * @Groups({"manage"})
     * 
     * @var string
     */
    private $title;

    /**
     * Set description
     *
     * @param string $description
     * @return Ad
     */
    public function setDescription($description)
    {
        $this->description = $description;

        return $this;
    }

    /**
     * Get description
     *
     * @return string 
     */
    public function getDescription()
    {
        return $this->description;
    }

    /**
     * Set country
     *
     * @param \Acme\SearchBundle\Entity\Country $country
     * @return Ad
     */
    public function setCountry($country)
    {
        $this->country= $country;

        return $this;
    }

    /**
     * Get country
     *
     * @return string 
     */
    public function getCountry()
    {
        return $this->country;
    }

    /**
     * Set title
     *
     * @param string $title
     * @return Ad
     */
    public function setTituloanuncio($title)
    {
        $this->title = $title;

        return $this;
    }

    /**
     * Get title
     *
     * @return string 
     */
    public function getTitle()
    {
        return $this->title;
    }

}

And the Entity of the relationship:

class Country
{

    /**
     * @Type("string")
     * @Groups("manage")
     * 
     * @var string
     */
    private $id;

    /**
     * @Type("string")
     * @Groups("admin")
     * 
     * @var string
     */
    private $description;

    /**
     * Set description
     * @Groups("")
     *
     * @param string $description
     * @return Country
     */
    public function setDescripcionpais($description)
    {
        $this->description = $description;

        return $this;
    }

    /**
     * Get description
     *
     * @return string 
     */
    public function getDescription()
    {
        return $this->description;
    }

    }

    /**
     * Get id
     *
     * @return string 
     */
    public function getId()
    {
        return $this->id;
    }
}

I serialize the entity but I don't know how to convert the country attribute into a simple field.

I get this result in json:

{"description":"foo", "title":"bar", "country":{"id":"en"} }

But I want to get the id field of the country like this:

{"description":"foo", "title":"bar", "country": "en" }

It is possible with JMS Serializer?

Thank you.

[EDIT]

@VirtualProperty doesn't work.

Answer 1

Yes, you could use @VirtualProperty annotation:

/**
 * @VirtualProperty
 * @SerializedName("foo")
 */
public function bar()
{
    return $this->country->getCode();
}

But be aware when it comes to deserialization:

@VirtualProperty This annotation can be defined on a method to indicate that the data returned by the method should appear like a property of the object.

> Note: This only works for serialization and is completely ignored during deserialization.

Hope this helps...

Answer 2

Just to follow answered question:

If you don't like writing one method for each relation you have - just write your own handler. It's easy like

final class RelationsHandler
{
    /**
     * @var EntityManagerInterface
     */
    private $manager;

    /**
     * RelationsHandler constructor.
     *
     * @param EntityManagerInterface $manager
     */
    public function __construct(EntityManagerInterface $manager) { $this->manager = $manager; }


    public function serializeRelation(JsonSerializationVisitor $visitor, $relation, array $type, Context $context)
    {
        if ($relation instanceof \Traversable) {
            $relation = iterator_to_array($relation);
        }

        if (is_array($relation)) {
            return array_map([$this, 'getSingleEntityRelation'], $relation);
        }

        return $this->getSingleEntityRelation($relation);
    }

    /**
     * @param $relation
     *
     * @return array|mixed
     */
    protected function getSingleEntityRelation($relation)
    {
        $metadata = $this->manager->getClassMetadata(get_class($relation));

        $ids = $metadata->getIdentifierValues($relation);
        if (!$metadata->isIdentifierComposite) {
            $ids = array_shift($ids);
        }

        return $ids;
    }
}

Register the Handler

  jms_serializer.handler.relation:
      class: MyBundle\RelationsHandler
      arguments:
      - "@doctrine.orm.entity_manager"
      tags:
      - { name: jms_serializer.handler, type: Relation, direction: serialization, format: json, method: serializeRelation}
      - { name: jms_serializer.handler, type: Relation, direction: deserialization, format: json, method: deserializeRelation}
      - { name: jms_serializer.handler, type: Relation<?>, direction: serialization, format: json, method: serializeRelation}
      - { name: jms_serializer.handler, type: Relation<?>, direction: deserialization, format: json, method: deserializeRelation}

This allows you to replace virtual getter methods with `Type("Relation").

If you also want't to deserialize relation - you should tell each @Type("Relation") the classname (@Type("Relation<FQCN>")) which it should deserialize to or wrap the metadata driver with one which do it for you.

    public function deserializeRelation(JsonDeserializationVisitor $visitor, $relation, array $type, Context $context)
    {
        $className = isset($type['params'][0]['name']) ? $type['params'][0]['name'] : null;

        if (!class_exists($className, false)) {
            throw new \InvalidArgumentException('Class name should be explicitly set for deserialization');
        }

        $metadata = $this->manager->getClassMetadata($className);

        if (!is_array($relation)) {
            return $this->manager->getReference($className, $relation);
        }

        $single = false;
        if ($metadata->isIdentifierComposite) {
            $single = true;
            foreach ($metadata->getIdentifierFieldNames() as $idName) {
                $single = $single && array_key_exists($idName, $relation);
            }
        }

        if ($single) {
            return $this->manager->getReference($className, $relation);
        }

        $objects = [];
        foreach ($relation as $idSet) {
            $objects[] = $this->manager->getReference($className, $idSet);
        }

        return $objects;
    }