In this case, I just wanted to make a custom field from ACF visible in the JSON returned for a custom post type which was named faculty.
add_action( 'rest_api_init', 'add_faculty_type_to_json' ); function add_faculty_type_to_json() { register_rest_field( 'faculty', //the post type of your choice 'faculty_type', //the name for your json element array( 'get_callback' => 'faculty_return_type', //the function that creates the content ) ); } // Return acf field staff_group function faculty_return_type( $object, $field_name, $request ) { global $post; $faculty_type = get_field('staff_group', $post->ID); return $faculty_type[0]; //multiple selections are possible here but in this use case I only want the first one }
That’s all there is to it.