jsonfg

Rust types for OGC Features and Geometries JSON (JSON-FG), the OGC extension of GeoJSON standardized as OGC 21-045r1 (version 1.0).

JSON-FG is a strict superset of GeoJSON. Where GeoJSON can only carry WGS 84 geometry of seven simple types, JSON-FG adds — as GeoJSON foreign members, so plain GeoJSON readers still work — the ability to convey:

geometry in any coordinate reference system, not just WGS 84, via the place member and coordRefSys;
geometry types beyond GeoJSON: 3D solids (Polyhedron, Prism, …) and curves (CircularString, CompoundCurve, CurvePolygon, …);
temporal information via time;
feature classification via featureType and featureSchema.

This crate is the JSON-FG counterpart to the geojson crate: a small, serde-based data model with no I/O or HTTP content-negotiation logic. It models every member of the JSON-FG 1.0 schema and preserves unknown members (e.g. OGC API links) verbatim, so documents round-trip losslessly.

Example

use jsonfg::{conformance, CoordRefSys, Feature, Geometry};

// A feature whose geometry is a point in a projected CRS (EPSG:3857). The native
// geometry goes in `place`; the GeoJSON `geometry` member is left null.
let mut feature = Feature::new();
feature.conforms_to = Some(vec![conformance::CORE.to_owned()]);
feature.coord_ref_sys = Some(CoordRefSys::from_epsg(3857));
feature.place = Some(Geometry::point(vec![100.0, 200.0]));

let json = serde_json::to_string(&feature).unwrap();

The place/geometry split is the producer's choice: put WGS 84 geometry in geometry, and geometry in any other CRS (or of a non-GeoJSON type) in place with coordRefSys. CoordRefSys::is_wgs84() helps decide.

Feature flags

geojson — From/TryFrom conversions to and from geojson::Geometry. (Arcs and solids have no GeoJSON equivalent and return an error when converting to GeoJSON.)

Status

Covers the JSON-FG 1.0 Core plus the Polyhedra, Prisms, Circular Arcs and Measures geometry types. Validated by round-tripping the normative OGC example corpus.

Releasing

Releases are published to crates.io automatically by GitHub Actions using crates.io Trusted Publishing (OIDC) — there is no API-token secret to manage. One-time setup: on the crate's crates.io Settings → Trusted Publishing page, add this repository (360-geo/jsonfg), the workflow publish.yaml, and the github environment if you use one.

To cut a release:

Land your changes on main, move the relevant CHANGELOG.md entries out of [Unreleased] into a new version heading, and make sure CI is green.
Publish a GitHub Release with a tag of the form vX.Y.Z (e.g. v0.1.0); use the changelog entry as the release notes.
.github/workflows/publish.yaml fires on the release, stamps the version from the tag into Cargo.toml, mints a short-lived token via OIDC, and runs cargo publish.

The Cargo.toml version is set from the tag at publish time, so the tag is the source of truth; keep the committed version in sync for local builds.

License