Rust serde for enum with unknown value in associated string variant

serde_enum_with_unknown_variant.rs

use serde::{Deserialize, Deserializer, Serialize, Serializer};

const FROM: &'static str = r#"[{"value":"unknown"},{"value": "one"}]"#;

#[derive(Serialize, Deserialize, Debug)]
#[serde(rename_all = "snake_case")]
pub enum To {
    One,
    Two,
    Three,
    Four,
    Five,
    Other(String),
}
#[derive(Serialize, Deserialize, Debug)]
struct Check {
    #[serde(deserialize_with = "check_enum_de")]
    #[serde(serialize_with = "check_enum_se")]
    value: To,
}

pub fn check_enum_de<'de, D: Deserializer<'de>>(d: D) -> Result<To, D::Error> {
    let as_string = String::deserialize(d)?;
    serde_json::from_str(&format!(r#""{}""#, &as_string)).or(Ok(To::Other(as_string)))
}

pub fn check_enum_se<S: Serializer>(value: &To, s: S) -> Result<S::Ok, S::Error> {
    if let To::Other(string) = value {
        string.serialize(s)
    } else {
        value.serialize(s)
    }
}

fn main() {
    let result: Vec<Check> = serde_json::from_str(FROM).unwrap();
    println!("{result:?} - {}", serde_json::to_string(&result).unwrap());
    // [Check { value: Other("unknown") }, Check { value: One }] - [{"value":"unknown"},{"value":"one"}]
}

Thanks to jonasbb and bruh![moment] from rust discord, a slight imrovement

pub fn check_enum_de<'de, D: Deserializer<'de>>(d: D) -> Result<To, D::Error> {
    let as_string = String::deserialize(d)?;
    let str_d: StrDeserializer<D::Error> = as_string.as_str().into_deserializer();
    To::deserialize(str_d).or(Ok(To::Other(as_string)))
}