WP_REST_Posts_Controller::prepare_taxonomy_limit_schema() WordPress Method

	private function prepare_taxonomy_limit_schema( array $query_params ) {
		$taxonomies = wp_list_filter( get_object_taxonomies( $this->post_type, 'objects' ), array( 'show_in_rest' => true ) );

		if ( ! $taxonomies ) {
			return $query_params;
		}

		$query_params['tax_relation'] = array(
			'description' => __( 'Limit result set based on relationship between multiple taxonomies.' ),
			'type'        => 'string',
			'enum'        => array( 'AND', 'OR' ),
		);

		$limit_schema = array(
			'type'  => array( 'object', 'array' ),
			'oneOf' => array(
				array(
					'title'       => __( 'Term ID List' ),
					'description' => __( 'Match terms with the listed IDs.' ),
					'type'        => 'array',
					'items'       => array(
						'type' => 'integer',
					),
				),
				array(
					'title'                => __( 'Term ID Taxonomy Query' ),
					'description'          => __( 'Perform an advanced term query.' ),
					'type'                 => 'object',
					'properties'           => array(
						'terms'            => array(
							'description' => __( 'Term IDs.' ),
							'type'        => 'array',
							'items'       => array(
								'type' => 'integer',
							),
							'default'     => array(),
						),
						'include_children' => array(
							'description' => __( 'Whether to include child terms in the terms limiting the result set.' ),
							'type'        => 'boolean',
							'default'     => false,
						),
					),
					'additionalProperties' => false,
				),
			),
		);

		$include_schema = array_merge(
			array(
				/* translators: %s: Taxonomy name. */
				'description' => __( 'Limit result set to items with specific terms assigned in the %s taxonomy.' ),
			),
			$limit_schema
		);
		// 'operator' is supported only for 'include' queries.
		$include_schema['oneOf'][1]['properties']['operator'] = array(
			'description' => __( 'Whether items must be assigned all or any of the specified terms.' ),
			'type'        => 'string',
			'enum'        => array( 'AND', 'OR' ),
			'default'     => 'OR',
		);

		$exclude_schema = array_merge(
			array(
				/* translators: %s: Taxonomy name. */
				'description' => __( 'Limit result set to items except those with specific terms assigned in the %s taxonomy.' ),
			),
			$limit_schema
		);

		foreach ( $taxonomies as $taxonomy ) {
			$base         = ! empty( $taxonomy->rest_base ) ? $taxonomy->rest_base : $taxonomy->name;
			$base_exclude = $base . '_exclude';

			$query_params[ $base ]                = $include_schema;
			$query_params[ $base ]['description'] = sprintf( $query_params[ $base ]['description'], $base );

			$query_params[ $base_exclude ]                = $exclude_schema;
			$query_params[ $base_exclude ]['description'] = sprintf( $query_params[ $base_exclude ]['description'], $base );

			if ( ! $taxonomy->hierarchical ) {
				unset( $query_params[ $base ]['oneOf'][1]['properties']['include_children'] );
				unset( $query_params[ $base_exclude ]['oneOf'][1]['properties']['include_children'] );
			}
		}

		return $query_params;
	}