alloy-serde

Serde helpers for Ethereum JSON-RPC formats that differ from Serde's defaults.

• quantity encodes primitive integers as canonical RPC quantities such as "0x2a". Its opt, vec, hashmap, and btreemap modules cover common containers.
• ttd handles geth's mixed number/string representation of terminal total difficulty.
• storage handles storage keys and zero-padding cropped storage values.
• WithOtherFields preserves unknown object fields for forwarding or round-tripping RPC payloads.

use serde::{Deserialize, Serialize};

#[derive(Debug, PartialEq, Serialize, Deserialize)]
struct Request {
    #[serde(with = "alloy_serde::quantity")]
    block: u64,
    // `default` is required if an omitted field should become `None`.
    #[serde(default, with = "alloy_serde::quantity::opt")]
    limit: Option<u64>,
}

let request: Request = serde_json::from_str(r#"{"block":"0x2a"}"#)?;
assert_eq!(request, Request { block: 42, limit: None });
assert_eq!(
    serde_json::to_string(&Request { block: 42, limit: Some(16) })?,
    r#"{"block":"0x2a","limit":"0x10"}"#,
);
# Ok::<(), serde_json::Error>(())

For deserialization-only helpers such as null_as_default, use deserialize_with and pair it with #[serde(default)] when missing fields should also use the default. The no-prefix hex helpers are serialization-only and therefore use serialize_with.