WP_REST_Sidebars_Controller::update_item( WP_REST_Request $request )

	public function update_item( $request ) {
		if ( isset( $request['widgets'] ) ) {
			$sidebars = wp_get_sidebars_widgets();

			foreach ( $sidebars as $sidebar_id => $widgets ) {
				foreach ( $widgets as $i => $widget_id ) {
					// This automatically removes the passed widget IDs from any other sidebars in use.
					if ( $sidebar_id !== $request['id'] && in_array( $widget_id, $request['widgets'], true ) ) {
						unset( $sidebars[ $sidebar_id ][ $i ] );
					}

					// This automatically removes omitted widget IDs to the inactive sidebar.
					if ( $sidebar_id === $request['id'] && ! in_array( $widget_id, $request['widgets'], true ) ) {
						$sidebars['wp_inactive_widgets'][] = $widget_id;
					}
				}
			}

			$sidebars[ $request['id'] ] = $request['widgets'];

			wp_set_sidebars_widgets( $sidebars );
		}

		$request['context'] = 'edit';

		$sidebar = $this->get_sidebar( $request['id'] );

		/**
		 * Fires after a sidebar is updated via the REST API.
		 *
		 * @since 5.8.0
		 *
		 * @param array           $sidebar The updated sidebar.
		 * @param WP_REST_Request $request Request object.
		 */
		do_action( 'rest_save_sidebar', $sidebar, $request );

		return $this->prepare_item_for_response( $sidebar, $request );
	}