Title: WP_REST_Controller::get_additional_fields
Published: December 6, 2016
Last modified: April 28, 2025

---

# WP_REST_Controller::get_additional_fields( string $object_type = null ): array

## In this article

 * [Parameters](https://developer.wordpress.org/reference/classes/WP_REST_Controller/get_additional_fields/?output_format=md#parameters)
 * [Return](https://developer.wordpress.org/reference/classes/WP_REST_Controller/get_additional_fields/?output_format=md#return)
 * [Source](https://developer.wordpress.org/reference/classes/WP_REST_Controller/get_additional_fields/?output_format=md#source)
 * [Related](https://developer.wordpress.org/reference/classes/WP_REST_Controller/get_additional_fields/?output_format=md#related)
 * [Changelog](https://developer.wordpress.org/reference/classes/WP_REST_Controller/get_additional_fields/?output_format=md#changelog)

[ Back to top](https://developer.wordpress.org/reference/classes/WP_REST_Controller/get_additional_fields/?output_format=md#wp--skip-link--target)

Retrieves all of the registered additional fields for a given object-type.

## 󠀁[Parameters](https://developer.wordpress.org/reference/classes/WP_REST_Controller/get_additional_fields/?output_format=md#parameters)󠁿

 `$object_type`stringoptional

The object type.

Default:`null`

## 󠀁[Return](https://developer.wordpress.org/reference/classes/WP_REST_Controller/get_additional_fields/?output_format=md#return)󠁿

 array Registered additional fields (if any), empty array if none or if the object
type could not be inferred.

## 󠀁[Source](https://developer.wordpress.org/reference/classes/WP_REST_Controller/get_additional_fields/?output_format=md#source)󠁿

    ```php
    protected function get_additional_fields( $object_type = null ) {
    	global $wp_rest_additional_fields;

    	if ( ! $object_type ) {
    		$object_type = $this->get_object_type();
    	}

    	if ( ! $object_type ) {
    		return array();
    	}

    	if ( ! $wp_rest_additional_fields || ! isset( $wp_rest_additional_fields[ $object_type ] ) ) {
    		return array();
    	}

    	return $wp_rest_additional_fields[ $object_type ];
    }
    ```

[View all references](https://developer.wordpress.org/reference/files/wp-includes/rest-api/endpoints/class-wp-rest-controller.php/)
[View on Trac](https://core.trac.wordpress.org/browser/tags/6.9.4/src/wp-includes/rest-api/endpoints/class-wp-rest-controller.php#L527)
[View on GitHub](https://github.com/WordPress/wordpress-develop/blob/6.9.4/src/wp-includes/rest-api/endpoints/class-wp-rest-controller.php#L527-L543)

## 󠀁[Related](https://developer.wordpress.org/reference/classes/WP_REST_Controller/get_additional_fields/?output_format=md#related)󠁿

| Uses | Description | 
| [WP_REST_Controller::get_object_type()](https://developer.wordpress.org/reference/classes/wp_rest_controller/get_object_type/)`wp-includes/rest-api/endpoints/class-wp-rest-controller.php` |

Retrieves the object type this controller is responsible for managing.

  |

| Used by | Description | 
| [WP_REST_Controller::get_fields_for_response()](https://developer.wordpress.org/reference/classes/wp_rest_controller/get_fields_for_response/)`wp-includes/rest-api/endpoints/class-wp-rest-controller.php` |

Gets an array of fields to be included on the response.

  | 
| [WP_REST_Controller::add_additional_fields_to_object()](https://developer.wordpress.org/reference/classes/wp_rest_controller/add_additional_fields_to_object/)`wp-includes/rest-api/endpoints/class-wp-rest-controller.php` |

Adds the values from additional fields to a data object.

  | 
| [WP_REST_Controller::update_additional_fields_for_object()](https://developer.wordpress.org/reference/classes/wp_rest_controller/update_additional_fields_for_object/)`wp-includes/rest-api/endpoints/class-wp-rest-controller.php` |

Updates the values of additional fields added to a data object.

  | 
| [WP_REST_Controller::add_additional_fields_schema()](https://developer.wordpress.org/reference/classes/wp_rest_controller/add_additional_fields_schema/)`wp-includes/rest-api/endpoints/class-wp-rest-controller.php` |

Adds the schema from additional fields to a schema array.

  |

## 󠀁[Changelog](https://developer.wordpress.org/reference/classes/WP_REST_Controller/get_additional_fields/?output_format=md#changelog)󠁿

| Version | Description | 
| [4.7.0](https://developer.wordpress.org/reference/since/4.7.0/) | Introduced. |

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