How to access the existing field value in a custom field?

Question

I have a content type which shows video in iframe from youtube. There is a field which I can enter the youtube link and it will render the iframe using the link.

I have created a custom field which will take the youtube link as input and get the youtube statistics using youtube api. The field will display a div in the page with view count and number of likes of the video.

I wanted to access the already existing field value (youtube link which shows iframe), to show my stats information, as both are same. In my custom field module, I am taking an input field which is the youtube url.

For a user, it will be repetitive, if he types the url twice. Also I already have so many contents added to my content types, so it will be a burden to the content creators to go and add values to my newly created field.

Is there any way, I can access the existing fields value of my same content type ?

Here is my code :

YoutubeStat.php

<?php

namespace Drupal\youtube_stat\Plugin\Field\FieldType;

use Drupal\Core\Field\FieldItemBase;
use Drupal\Core\TypedData\DataDefinition;
use Drupal\Core\Field\FieldStorageDefinitionInterface as StorageDefinition;

/**
 * Plugin implementation of the 'player_info' field type.
 *
 * @FieldType(
 *   id = "Youtube_stat",
 *   label = @Translation("Youtube statistics"),
 *   description = @Translation("To Display Youtube statistics"),
 *   category = @Translation("Custom"),
 *   default_widget = "Youtube_statDefaultWidget",
 *   default_formatter = "Youtube_statDefaultFormatter"
 * )
 */
class Youtube_stat extends FieldItemBase {

  /**
   * Field type properties definition.
   * 
   * Inside this method we defines all the fields (properties) that our 
   * custom field type will have.
   * 
   * Here there is a list of allowed property types: https://goo.gl/sIBBgO
   */
  public static function propertyDefinitions(StorageDefinition $storage) {

    $properties = [];

    $properties['videoId'] = DataDefinition::create('string')
      ->setLabel(t('Video Id'));

    return $properties;
  }

  /**
   * Field type schema definition.
   * 
   * Inside this method we defines the database schema used to store data for 
   * our field type.
   * 
   * Here there is a list of allowed column types: https://goo.gl/YY3G7s
   */
  public static function schema(StorageDefinition $storage) {

    $columns = [];

    $columns['videoId'] = [
      'type' => 'char',
      'length' => 255,
    ];

    return [
      'columns' => $columns,
      'indexes' => [],
    ];
  }

  /**
   * Define when the field type is empty. 
   * 
   * This method is important and used internally by Drupal. Take a moment
   * to define when the field fype must be considered empty.
   */
  public function isEmpty() {

    $isEmpty = 
      empty($this->get('videoId')->getValue());

    return $isEmpty;
  }



}

YoutubeStatDefaultFormatter.php

    <?php

namespace Drupal\youtube_stat\Plugin\Field\FieldFormatter;

use Drupal\Core\Field\FieldItemListInterface;
use Drupal\Core\Field\FormatterBase;
use Drupal;

/**
 * Plugin implementation of the 'Youtube_statDefaultFormatter' formatter.
 *
 * @FieldFormatter(
 *   id = "Youtube_statDefaultFormatter",
 *   label = @Translation("Youtube statisctics"),
 *   field_types = {
 *     "Youtube_stat"
 *   }
 * )
 */
class Youtube_statDefaultFormatter extends FormatterBase {

  /**
   * Define how the field type is showed.
   * 
   * Inside this method we can customize how the field is displayed inside 
   * pages.
   */
  public function viewElements(FieldItemListInterface $items, $langcode) {


    \Drupal::service('page_cache_kill_switch')->trigger();
    //$memory = (string)ini_get("memory_limit");
      //ini_set('memory_limit', '-1');
    $elements = [];
    foreach ($items as $delta => $item) {

      $JSON = file_get_contents("https://www.googleapis.com/youtube/v3/videos?key=*_API_KEY_*&part=statistics&id={$item->videoId}");
      $JSON_Data = json_decode($JSON);
      $viewCount = $JSON_Data->items[0]->statistics->viewCount;
      $likeCount = $JSON_Data->items[0]->statistics->likeCount;
      //$dump_data = '<pre>'.json_encode($item).'<pre>';
      $stat_div = "<div><span>Views : ".$viewCount."</span>&nbsp;<span>Likes : ".$likeCount."</span></div>";
      //$result = $query->fetchAll();
      $elements[$delta] = [
        '#type' => 'markup',
        '#markup' => $stat_div,
        '#cache' => ['max-age' => 0]
      ];
    }
    //ini_set('memory_limit', $memory);
    return $elements;
  }



}

Is there any way to achieve this ?

Answer 1

I don't think this warrants a custom field but could be handled many other ways. A couple options here

1.) You can preprocess the node and provide your value as a variable to use in the node.tpl.php template.

2.) Create a new Drupal field and use hook_form_alter and on your submit take the value from the youtube field and place it into your new field. Then hide the field from the end user when they edit the node. Then run a one time function to loop through existing content types and update it with the youtube value.