Enums & Tagging

use serde::{Deserialize, Serialize};
 
#[derive(Serialize, Deserialize)]
#[serde(tag = "type", content = "data")]
enum Event {
    Click { x: i32, y: i32 },
    KeyPress { key: String },
}
// {"type":"Click","data":{"x":1,"y":2}}

use serde::{Deserialize, Serialize};
 
#[derive(Debug, Serialize, Deserialize, PartialEq)]
#[serde(tag = "type")]
enum Message {
    Text { body: String },
    Image { url: String, width: u32 },
}
 
#[derive(Debug, Serialize, Deserialize, PartialEq)]
#[serde(untagged)]
enum LooseId {
    Number(u64),
    Text(String),
}
 
#[derive(Debug, Serialize, Deserialize, PartialEq)]
#[serde(tag = "kind", content = "value")]
enum Payment {
    Card { last4: String },
    Bank { routing: String },
}
 
fn main() {
    let m = Message::Text { body: "hi".into() };
    let json = serde_json::to_string(&m).unwrap();
    assert!(json.contains(r#""type":"Text""#));
 
    let id_num: LooseId = serde_json::from_str("42").unwrap();
    let id_str: LooseId = serde_json::from_str(r#""abc""#).unwrap();
    assert!(matches!(id_num, LooseId::Number(42)));
 
    let p = Payment::Card { last4: "4242".into() };
    let pjson = serde_json::to_string(&p).unwrap();
    assert!(pjson.contains(r#""kind":"Card""#));
}

#[derive(Serialize, Deserialize)]
#[serde(rename_all = "snake_case", tag = "event")]
enum Audit { UserCreated { id: u64 }, UserDeleted { id: u64 } }