HL7 Rust

Crates

hl7-3-derive

#[derive(FromElement)] for HL7 v3 struct mode

Tooling and helpers v0.1.1

Install cargo add hl7-3-derive
Rust path hl7_3_derive
Dependencies syn,quote
Links crates.io docs.rs source

What it is

Maps struct fields to XML element attributes and children. Like its v2 cousin it arrives through a feature rather than a direct dependency — and unlike it, nothing here returns a `Result`: a missing attribute reads as that field’s `Default`, matching `hl7-3`’s own degrade-don’t-reject choice.

toml 
hl7-3 = { version = "0.1", features = ["derive"] }

Keeping the macro in a crate of its own is what lets the default build of hl7-3 keep exactly one dependency: syn and quote are compiled only for callers who ask for it.

Usage

rust 
use hl7_3::FromElement;
use hl7_3::rim::Act;

#[derive(FromElement, Default)]
struct Observation {
    #[element("classCode")]          class_code: String,
    #[element("moodCode")]           mood_code: String,
    #[element(child = "note")]       note: Option<String>,
    #[element(nested = "component")] component: Act,        // its own FromElement
    #[element(raw)]                  raw: hl7_3::xml::Element, // the escape hatch
}

let element = hl7_3::xml::parse(xml)?;
let observation = Observation::from_element(&element);
assert_eq!(observation.class_code, "OBS");

// The one attribute no struct field models — same object, no second parse.
assert_eq!(observation.raw.attribute("negationInd"), Some("true"));

The attributes

AttributeReads
#[element("classCode")]The classCode attribute.
#[element(child = "note")]The note child's text.
#[element(nested = "component")]The component child, via the field type's own FromElement.
#[element(raw)]The whole element, as hl7_3::xml::Element.
noneDefault::default()

Field types

Field types convert through hl7_3::typed::FromElementValue: String, bool, and the integer and floating-point types, plus Option<T> of any of those.

There is no Vec<T> support yet — a repeating child needs element.children_named(...) by hand for now.

Two deliberate differences from the v2 macro

No Result anywhere

Unlike hl7-2-derive's #[derive(FromHl7)], a missing attribute or child is not an error — it reads as that field's Default, the same degrade-don't-reject choice hl7-3's own rim types make. See that crate's typed module documentation for why.

No #[derive(ToElement)]

hl7-3 has no XML-writing capability yet, so a write-direction macro would have nothing real to generate.

This crate has no spec/index.md of its own; its behavior is documented in its README and in hl7-3's typed module. A fuller walkthrough is in Struct mode and derive.

hl7-3

HL7 v3: the RIM backbone, the data types, the message envelope

hl7-2-derive

#[derive(FromHl7)] and #[derive(ToHl7)] for struct mode