Other Formats

Serde plugs into many wire formats beyond JSON - each crate implements the same Serialize/Deserialize traits.

Recipe

Quick-reference recipe card - copy-paste ready.

use serde::{Deserialize, Serialize};
 
#[derive(Serialize, Deserialize)]
struct Config { host: String, port: u16 }
 
let toml_str = toml::to_string(&config)?;
let yaml_str = serde_yaml::to_string(&config)?;
let bytes = bincode::serde::encode_to_vec(&config, bincode::config::standard())?;

When to reach for this: Pick the format that matches your consumer - human config files, compact RPC, or cross-language messaging.

Working Example

use serde::{Deserialize, Serialize};
 
#[derive(Debug, Serialize, Deserialize, PartialEq)]
struct Config {
    host: String,
    port: u16,
    #[serde(default)]
    workers: u32,
}
 
fn main() -> Result<(), Box<dyn std::error::Error>> {
    let cfg = Config { host: "127.0.0.1".into(), port: 3000, workers: 4 };
 
    let toml_text = toml::to_string(&cfg)?;
    let from_toml: Config = toml::from_str(&toml_text)?;
 
    let yaml_text = serde_yaml::to_string(&cfg)?;
    let from_yaml: Config = serde_yaml::from_str(&yaml_text)?;
 
    let bytes = bincode::serde::encode_to_vec(&cfg, bincode::config::standard())?;
    let (from_bin, _len): (Config, usize) =
        bincode::serde::decode_from_slice(&bytes, bincode::config::standard())?;
 
    assert_eq!(from_toml, from_bin);
    Ok(())
}

What this demonstrates:

• Same struct serializes to TOML, YAML, and bincode without changes.
• default attribute helps config files omit optional keys.
• bincode produces compact binary for service-to-service storage.

Deep Dive

Format Guide

Rust Notes

// MessagePack
let mut buf = Vec::new();
rmp_serde::encode::write(&mut buf, &cfg)?;

Gotchas

• YAML security - Arbitrary YAML can be complex to parse safely. Fix: Treat YAML as trusted config only; prefer TOML for apps.
• bincode not portable across languages - Binary layout is Rust-centric. Fix: Use JSON, Protobuf, or MessagePack for polyglot systems.
• Format-specific types - toml::Value vs serde_json::Value differ. Fix: Stick to shared structs at boundaries.
• Enum representation differs - Tagged enum JSON shape != bincode layout. Fix: Test round-trip per format in CI.
• Large YAML aliases - Billion laughs attack. Fix: Limit loader depth/size in untrusted contexts.

Alternatives

FAQs

Related

• serde Basics - Trait fundamentals
• JSON with serde_json - Default wire format
• Customizing Serialization - Attributes
• serde Best Practices - Schema stability
• Configuration and Secrets - Prod config

Stack versions: This page was written for Rust 1.97.0 (edition 2024), Tokio 1.x, Axum 0.8, serde 1.0, sqlx 0.8, clap 4, and Polars 0.46+.