use std::fmt;
use std::str::FromStr;
use serde::{de, Deserialize, Deserializer};

#[derive(Debug, Deserialize)]
pub struct Params {
    #[serde(default, deserialize_with="empty_string_as_none")]
    pub transaction_id: Option<i64>,
}

// Serde deserialization decorator to map empty Strings to None,
fn empty_string_as_none<'de, D, T>(de: D) -> Result<Option<T>, D::Error>
where
    D: Deserializer<'de>,
    T: FromStr,
    T::Err: fmt::Display,
{
    let opt = Option::<String>::deserialize(de)?;
    match opt.as_deref() {
        None | Some("") => Ok(None),
        Some(s) => FromStr::from_str(s).map_err(de::Error::custom).map(Some),
    }
}