EntityLazyLoadContext.php

<?php

namespace Drupal\ctools\Context;

use Drupal\Core\Entity\EntityRepositoryInterface;
use Drupal\Core\Plugin\Context\Context;
use Drupal\Core\Plugin\Context\ContextDefinitionInterface;

/**
 * Defines context that loads entity on demand.
 */
class EntityLazyLoadContext extends Context {
    
    /**
     * The entity UUID.
     *
     * @var string
     */
    protected $uuid;
    
    /**
     * The entity repository.
     *
     * @var \Drupal\Core\Entity\EntityRepositoryInterface
     */
    protected $entityRepository;
    
    /**
     * Construct an EntityLazyLoadContext object.
     *
     * @param \Drupal\Core\Plugin\Context\ContextDefinitionInterface $context_definition
     *   The context definition.
     * @param \Drupal\Core\Entity\EntityRepositoryInterface $entity_repository
     *   The entity repository.
     * @param string $uuid
     *   The UUID of the entity.
     */
    public function __construct(ContextDefinitionInterface $context_definition, EntityRepositoryInterface $entity_repository, $uuid) {
        parent::__construct($context_definition);
        $this->entityRepository = $entity_repository;
        $this->uuid = $uuid;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getContextValue() {
        if (!$this->contextData) {
            $entity_type_id = substr($this->contextDefinition
                ->getDataType(), 7);
            $this->setContextValue($this->entityRepository
                ->loadEntityByUuid($entity_type_id, $this->uuid));
        }
        return parent::getContextValue();
    }
    
    /**
     * {@inheritdoc}
     */
    public function hasContextValue() {
        // Ensure that the entity is loaded before checking if it exists.
        if (!$this->contextData) {
            $this->getContextValue();
        }
        return parent::hasContextValue();
    }

}