How to get API-Platform to load related (e.g. Many2One) resources/entities?

Question

According to the documentation, api-platform will eager-load related resources by default.

But on the default configuration, all my queries to resources with relations (mostly with typical Many2One relationships) populate these properties with the object IRI instead of the serialized object.

E.g., for this entity:

/**
 * @ORM\Entity(repositoryClass="App\Repository\BoostLeadContactActionRepository")
 * @ORM\Table(name="BoostLeadContactActions")
 */
class BoostLeadContactAction {

    /**
     * @ORM\Id()
     * @ORM\GeneratedValue()
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\ManyToOne(targetEntity="App\Entity\BoostLead", inversedBy="contacts")
     * @ORM\JoinColumn(nullable=false)
     */
    private $boostLead;

    /**
     * @ORM\ManyToOne(targetEntity="App\Entity\ContactChannel", fetch="EAGER")
     * @ORM\JoinColumn(nullable=false, referencedColumnName="Id")
     */
    private $channel;

    // getters/setters/extra properties removed for brevity
}

Then we have the corresponding ContactChannel:

/**
 * ContactChannel
 *
 * @ORM\Table(name="ContactChannels")
 * @ORM\Entity
 */
class ContactChannel {

    /**
     * @var int
     *
     * @ORM\Column(name="Id", type="smallint", nullable=false, options={"unsigned"=true})
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="IDENTITY")
     */
    private $id;

    /**
     * @var string
     *
     * @ORM\Column(name="Name", type="string", length=64, nullable=false)
     */
    private $name = '';
}

I've set up fetch="EAGER" on the relationship even if in theory is not needed. My configuration is the default, but just in case I actually wrote this in my api_platform.yaml:

    eager_loading:
        # To enable or disable eager loading.
        enabled: true

        # Fetch only partial data according to serialization groups.
        # If enabled, Doctrine ORM entities will not work as expected if any of the other fields are used.
        fetch_partial: false

        # Max number of joined relations before EagerLoading throws a RuntimeException.
        max_joins: 30

        # Force join on every relation.
        # If disabled, it will only join relations having the EAGER fetch mode.
        force_eager: true

The result of debug:config api_platform confirms the correct configuration is applied:

Current configuration for extension with alias "api_platform"
=============================================================

api_platform:
    title: FooBar API
    description: 'FooBar API, only for authenticated use'
    version: 0.8.0
    name_converter: null
    path_segment_name_generator: api_platform.path_segment_name_generator.underscore
    eager_loading:
        enabled: true
        fetch_partial: false
        max_joins: 30
        force_eager: true

And yet the results will be something like:

{
  "@context": "/api/contexts/BoostLeadContactAction",
  "@id": "/api/boost_lead_contact_actions/9",
  "@type": "BoostLeadContactAction",
  "id": 9,
  "boostLead": "/api/boost_leads/30",
  "channel": "/api/contact_channels/1",
  "direction": "outgoing",
  "successful": true,
  "type": "/api/lead_contact_attempt_reasons/1",
  "notes": "2",
  "createdAt": "2019-05-16T10:27:33+00:00",
  "updatedAt": "2019-05-16T10:27:33+00:00"
}

"boostLead", "channel" and "type" should be actual entities, eagerly loaded, but only IRIs are returned instead. I confirmed that the SQL query performed does not include any kind of join.

Funnily enough, it seems to be the opposite trouble than this other user is having. I wish I had their problems.

What could be preventing these relationships to be loaded eagerly? The relationships work otherwise (I can do other queries with Doctrine, or create custom serialization groups and the related properties will be included).

Answer 1

By default dereferenceable IRIs are used to display the related associations. Looking at the executed statements you should not see an explicit JOIN query but rather additional SELECT statements for the related associations.

If you are wanting the JSON representation of the associated object. You need to specify the Serialization @Groups for the desired properties in the related association. This will cause the SELECT statement to add in a JOIN to retrieve the related data to be serialized.

For more details see https://api-platform.com/docs/core/serialization/#embedding-relations

namespace App\Entity;

use ApiPlatform\Core\Annotation\ApiResource;
use Symfony\Component\Serializer\Annotation\Groups;

/**
 * @ApiResource(normalizationContext={ "groups": {"boost"} })
 * @ORM\Entity()
 * @ORM\Table(name="BoostLeadContactActions")
 */
class BoostLeadContactAction {

    /**
     * @ORM\Id()
     * @ORM\GeneratedValue()
     * @ORM\Column(type="integer")
     * @Groups({"boost"})
     */
    private $id;

    /**
     * @ORM\ManyToOne(targetEntity="App\Entity\BoostLead", inversedBy="contacts")
     * @ORM\JoinColumn(nullable=false)
     * @Groups({"boost"})
     */
    private $boostLead;

    /**
     * @ORM\ManyToOne(targetEntity="App\Entity\ContactChannel", fetch="EAGER")
     * @ORM\JoinColumn(nullable=false, referencedColumnName="Id")
     * @Groups({"boost"})
     */
    private $channel;

    // getters/setters/extra properties removed for brevity
}

namespace App\Entity;

use ApiPlatform\Core\Annotation\ApiResource;
use Symfony\Component\Serializer\Annotation\Groups;

/**
 * @ApiResource()
 * @ORM\Table(name="ContactChannels")
 * @ORM\Entity
 */
class ContactChannel {

    /**
     * @var int
     * @ORM\Column(name="Id", type="smallint", nullable=false, options={"unsigned"=true})
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="IDENTITY")
     * @Groups({"boost"})
     */
    private $id;

    /**
     * @var string
     * @ORM\Column(name="Name", type="string", length=64, nullable=false)
     * @Groups({"boost"})
     */
    private $name = '';
}

Which should result in the normalized values being retrieved

{
  "@context": "/api/contexts/BoostLeadContactAction",
  "@id": "/api/boost_lead_contact_actions/9",
  "@type": "BoostLeadContactAction",
  "id": 9,
  "boostLead": "/api/boost_leads/30",
  "channel": {
      "@id": "/api/contact_channels/1",
      "@type": "ContactChannel",
      "id": "1",
      "name": "Test"
   },
  "direction": "outgoing",
  "successful": true,
  "type": "/api/lead_contact_attempt_reasons/1",
  "notes": "2",
  "createdAt": "2019-05-16T10:27:33+00:00",
  "updatedAt": "2019-05-16T10:27:33+00:00"
}