Function deserialize_optional_string_to_u64 

pub fn deserialize_optional_string_to_u64<'de, D>(
    deserializer: D,
) -> Result<Option<u64>, D::Error>
where
    D: Deserializer<'de>,

Deserializes an optional u64 from a string field.

Returns None if the value is null or the string is empty.

Errors

Returns an error if the string cannot be parsed as a u64.