The Reflex of Deriving `serde` Traits

Published on 6 June 2026, 147 words, 1 minutes read

This popped up in “This Week in Rust” #653 by Evgeniy Terekhin (verrchu).

The DomainObject type is mentioned in the article however one must refer to the full source to see its From conversion, as I have included below

impl From<core::DomainObject> for DomainObjectFe {
    fn from(value: core::DomainObject) -> Self {
        Self {
            name: value.name,
            unix_ts: Some(value.unix_ts),
        }
    }
}

This lets you call .into() to perform the value conversion. Since it is an owned value, it is also cloned as it is used twice in this particular example.

fn example() {
    let core_obj = core::DomainObject {
        name: "hello".to_string(),
        unix_ts: core::UnixTimestamp(1_700_000_000_000_000_000),
    };

    let fe_obj: fe::DomainObjectFe = core_obj.clone().into();
    let db_obj: db::DomainObjectDb = core_obj.into();
}

Demonstrating deserialization (deser)

In my ledger system, I am using rust_decimal’s Decimal type and value conversions are either manual or implementing From. Full accompanying source code can be found here to demonstrate deserialization.

Note how we are deserializing from a String value of "42" to Decimal.

fn main() {
    let core_obj = core::CalculationsDO {
        interest: core::InterestTotal(Decimal::new(100, 0)),
    };

    // serialize
    let db_obj: db::DomainObjectDb = core_obj.clone().into();
    assert_eq!(
        serde_json::to_string_pretty(&db_obj).unwrap(),
        r#"{
  "interest": "100"
}"#
    );

    // deserialize
    let json = r#"
    {
        "interest": "42"
    }
    "#;
    let obj: db::DomainObjectDb = serde_json::from_str(json).unwrap();
    let converted: CalculationsDO = obj.into();
    assert_eq!(converted.interest, InterestTotal(Decimal::new(42, 0)));
}