Rest Resource Plugin

MySyncResource.php

<?php

namespace Drupal\ssync_client\Plugin\rest\resource;

use Drupal\file\Entity\File;
use Drupal\rest\Plugin\ResourceBase;
use Drupal\rest\ResourceResponse;

/**
 * Manipulate the image creation.
 *
 * @RestResource(
 *   id = "ssync_slave_create_file",
 *   label = @Translation("Ssync Slave rest resource"),
 *   serialization_class = "",
 *   uri_paths = {
 *     "canonical" = "/ssync/create_file"
 *   }
 * )
 */
class CreateFileResource extends ResourceBase {

  /**
   * Handle the post METHOD.
   *
   * @param array $data
   *   Post Array.
   *
   * @return \Drupal\rest\ResourceResponse
   *   Resource formatted with JSON API.
   */
  public function post(array $data = []) {

    $uri_file_unmanaged = file_unmanaged_save_data(file_get_contents($data->attributes->url), file_default_scheme() . '://');

    $file = File::create([
      'uuid' => $data->id,
      'uri' => $uri_file_unmanaged,
    ]);
    $file->save();

    return new ResourceResponse($file);
  }

}