Function deserialize_empty_string_or_parse 

pub fn deserialize_empty_string_or_parse<'de, T, D>(
    deserializer: D,
) -> Result<Option<T>, D::Error>
where
    D: Deserializer<'de>,
    T: FromStr,
    T::Err: Display,

deserialize an optional value with a FromStr implementation where None is represented as an empty string

Errors

returns an error if the value can not be interpreted as null or a String