ShapeItem.php

<?php

namespace Drupal\entity_test\Plugin\Field\FieldType;

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

/**
 * Defines the 'shape' field type.
 *
 * @FieldType(
 *   id = "shape",
 *   label = @Translation("Shape"),
 *   description = @Translation("Another dummy field type."),
 * )
 */
class ShapeItem extends FieldItemBase {
    
    /**
     * {@inheritdoc}
     */
    public static function defaultStorageSettings() {
        return [
            'foreign_key_name' => 'shape',
        ] + parent::defaultStorageSettings();
    }
    
    /**
     * {@inheritdoc}
     */
    public static function propertyDefinitions(FieldStorageDefinitionInterface $field_definition) {
        $properties['shape'] = DataDefinition::create('string')->setLabel(t('Shape'));
        $properties['color'] = DataDefinition::create('string')->setLabel(t('Color'));
        return $properties;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function schema(FieldStorageDefinitionInterface $field_definition) {
        $foreign_keys = [];
        // The 'foreign keys' key is not always used in tests.
        if ($field_definition->getSetting('foreign_key_name')) {
            $foreign_keys['foreign keys'] = [
                // This is a dummy foreign key definition, references a table that
                // doesn't exist, but that's not a problem.
$field_definition->getSetting('foreign_key_name') => [
                    'table' => $field_definition->getSetting('foreign_key_name'),
                    'columns' => [
                        $field_definition->getSetting('foreign_key_name') => 'id',
                    ],
                ],
            ];
        }
        return [
            'columns' => [
                'shape' => [
                    'type' => 'varchar',
                    'length' => 32,
                ],
                'color' => [
                    'type' => 'varchar',
                    'length' => 32,
                ],
            ],
        ] + $foreign_keys;
    }
    
    /**
     * {@inheritdoc}
     */
    public function isEmpty() {
        $item = $this->getValue();
        return empty($item['shape']) && empty($item['color']);
    }
    
    /**
     * {@inheritdoc}
     */
    public static function mainPropertyName() {
        return 'shape';
    }

}