How to parse yaml conditional fields in rust?

In the yaml files below:

// 1. book yaml
kind: book
title: Someone's life

publisher: someone
published_at: 2023-02-24T09:31:00Z+09:00

// 2. movie yaml
kind: movie
title: Someone's life

director: someone else

kind is key for recognizing that yaml is what for. If kind is book, this matter have publisher and published_at. however, if kind is movie, this matter doesn't have publisher but director.

In my short thought, for parsing it, i have to make general parse struct. ex:

#[derive(Serialize, Deserialize, Debug)]
struct General {
  kind: String,
  title: String,
}

parse one time using General struct, then get parsed general's kind and re-parse with another struct. ex:

#[derive(Serialize, Deserialize, Debug)]
struct Book {
  kind: String,
  title: String,
  publisher: String,
  published_at: String,
}

Above scenario can be works, but i have to parse two time. But, Is this efficient?

You can use serde's tag attribute for this. Playground example

use serde::Deserialize;
use serde_yaml; // 0.8.26

#[derive(Debug, Deserialize)]
#[serde(tag="kind", rename_all="lowercase")]
enum Media {
    Book(Book),
    Movie(Movie),
}

#[derive(Debug, Deserialize)]
struct Book {
    title: String,
    publisher: String,
    published_at: String,
}

#[derive(Debug, Deserialize)]
struct Movie {
    title: String,
    director: String,
}

fn main() {
    let book: Media = serde_yaml::from_str("kind: book
title: Someone's life

publisher: someone
published_at: 2023-02-24T09:31:00Z+09:00").unwrap();

    let movie: Media = serde_yaml::from_str("kind: movie
title: Someone's life

director: someone else").unwrap();

    println!("{book:?}");
    println!("{movie:?}");

}