Suggestions for oneof handling

[wagenet]

I'm not sure exactly where to put this, but it seems relevant to this repo. I used the strum crate to help out here.

In the build script

        // Don't tag oneof enums
        .type_attribute(path, "#[serde(untagged)]")
        // Make enum variant name serializable as lowercase
        .type_attribute(path, "#[derive(::strum::Display)]")
        .type_attribute(path, r#"#[strum(serialize_all = "snake_case")]"#)
        // Use custom serializer and flatten
        .field_attribute(
            path,
            r#"#[serde(flatten, serialize_with = "serialize_oneof")]"#,
        )

Then in my main code:

use serde::{Serialize, Serializer, ser::SerializeMap};
use std::fmt::Display;

pub fn serialize_oneof<T, S>(value: &Option<T>, serializer: S) -> Result<S::Ok, S::Error>
where
    T: Display + serde::Serialize,
    S: Serializer,
{
    match value {
        Some(v) => {
            let mut s = serializer.serialize_map(Some(1))?;
            s.serialize_entry(&format!("{}", v), v)?;
            s.end()
        }
        None => serializer.serialize_none(),
    }
}

[fdeantoni]

This is an interesting solution as well. I will add it to the README as an alternative.