Drupal 9 Custom Field Module: Integrating Address Field with Field Widget

Here's a comprehensive guide to creating a custom field module with an address field and widget in Drupal 9, incorporating best practices and addressing potential issues:

1. Module Structure:

• Create a custom module directory (e.g., modules/custom/my_address_field)
• Inside, create the following files:
  • my_address_field.info.yml
  • my_address_field.module
  • src/Plugin/Field/FieldType/AddressItem.php
  • src/Plugin/Field/FieldWidget/AddressWidget.php

2. Define the Field Type (AddressItem.php):

<?php

namespace Drupal\my_address_field\Plugin\Field\FieldType;

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

/**
 * Plugin implementation of the 'address_field' field type.
 *
 * @FieldType(
 *   id = "address_field",
 *   label = @Translation("Address"),
 *   description = @Translation("Stores a full address with components."),
 *   default_widget = "address_widget",
 *   default_formatter = "address_default"
 * )
 */
class AddressItem extends FieldItemBase {

  /**
   * {@inheritdoc}
   */
  public static function schema(FieldStorageDefinitionInterface $field_definition) {
    return [
      'columns' => [
        'street' => [
          'type' => 'varchar',
          'length' => 255,
        ],
        'city' => [
          'type' => 'varchar',
          'length' => 128,
        ],
        'country' => [
          'type' => 'varchar',
          'length' => 128,
        ],
        // Add more fields as needed (e.g., state, zip code, etc.)
      ],
    ];
  }

  // ... other necessary methods for handling field data
}

3. Create the Field Widget (AddressWidget.php):

<?php

namespace Drupal\my_address_field\Plugin\Field\FieldType;

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

/**
 * Plugin implementation of the 'address_field' field type.
 *
 * @FieldType(
 *   id = "address_field",
 *   label = @Translation("Address"),
 *   description = @Translation("Stores a full address with components."),
 *   default_widget = "address_widget",
 *   default_formatter = "address_default"
 * )
 */
class AddressItem extends FieldItemBase {

  /**
   * {@inheritdoc}
   */
  public static function schema(FieldStorageDefinitionInterface $field_definition) {
    return [
      'columns' => [
        'street' => [
          'type' => 'varchar',
          'length' => 255,
        ],
        'city' => [
          'type' => 'varchar',
          'length' => 128,
        ],
        'country' => [
          'type' => 'varchar',
          'length' => 128,
        ],
        // Add more fields as needed (e.g., state, zip code, etc.)
      ],
    ];
  }

  // ... other necessary methods for handling field data
}

4. Module Information and Enablement:

• Fill in my_address_field.info.yml with essential module information.
• Clear cache and enable the module.

5. Add the Field to Content Types:

• Go to Structure -> Content Types -> Manage Fields.
• Add a new field of type "Address".
• Configure the field settings and save.

Remember:

• Implement other methods like propertyDefinitions(), getConstraints(), and format() as needed for complete functionality.