I am saving in append mode a stream of events on a YAML log file, where each event is represented by an indivual document, like this:
---
type: event
id: 1
---
type: trigger
id: 2
At some point later I want to iterate on these events, parsing each via serde_yaml. To my understanding though, serde_yaml doesn't seem to support parsing multiple documents from a single reader, as none of the available methods mention it, and trying to parse multiple documents at once results in a MoreThanOneDocument error.
use std::io::{self, BufRead};
use serde_yaml;
use serde::{self, Deserialize};
#[derive(Deserialize, Debug)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum Message {
Event { id: i32 },
Trigger { id: i32},
}
fn main() -> io::Result<()> {
let yaml = "---\ntype: event\nid: 1\n---\n\ntype: trigger\nid: 2";
let v: Message = serde_yaml::from_reader(yaml.as_bytes()).unwrap();
println!("{:?}", v);
Ok(())
}
I'm totally new to Rust, so maybe I completely missed the point of serde and just did not understand how to do it.
How would you parse such YAML, please?
I cooked up something that looks like a working solution, but I think I'll try to post it among the answers instead, because I don't want to bias other answers too much towards my solution. I kindly encourage you to have a look at it as well however, any feedback is welcome.
The documentation of serde_yaml::Deserializer shows an example very similar to yours. It would work like this:
use serde::Deserialize;
#[derive(Deserialize, Debug)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum Message {
Event { id: i32 },
Trigger { id: i32 },
}
fn main() {
let yaml = "---\ntype: event\nid: 1\n---\ntype: trigger\nid: 2\n";
for document in serde_yaml::Deserializer::from_str(yaml) {
let v = Message::deserialize(document).unwrap();
println!("{:?}", v);
}
}