// GetStructModifiableFields returns an array of field names that do not have a
// readonly:"true" struct tag
func GetStructModifiableFields(s interface{}) (fields []reflect.StructField) {
	structFields := reflect.VisibleFields(reflect.TypeOf(s))
	for _, f := range structFields {
		if f.Tag.Get("readonly") != "true" {
			fields = append(fields, f)
		}
	}
	return
}