rust-postgis

Documentation

An extension to rust-postgres, adds support for PostGIS.

• PostGIS type helper
• GCJ02 support (used offically in Mainland China)
• Tiny WKB (TWKB) support
• Optional serialization/deserialization support via serde

Usage

use postgres::{Client, NoTls};
use postgis::{ewkb, LineString};

fn main() {
    let mut client = Client::connect("host=localhost user=postgres", NoTls).unwrap();
    for row in &client.query("SELECT * FROM busline", &[]).unwrap() {
        let route: ewkb::LineString = row.get("route");
        let last_stop = route.points().last().unwrap();
        let _ = client.execute("INSERT INTO stops (stop) VALUES ($1)", &[&last_stop]);
    }
}

Handling NULL values:

let route = row.try_get::<_, Option<ewkb::LineString>>("route");
match route {
    Ok(Some(geom)) => { println!("{:?}", geom) }
    Ok(None) => { /* Handle NULL value */ }
    Err(err) => { println!("Error: {}", err) }
}

Writing other geometry types into PostGIS

rust-postgis supports writing geometry types into PostGIS which implement the following traits:

• Point, LineString, ...
• AsEwkbPoint, AsEwkbLineString, ...

See the TWKB implementation as an example.

An example for reading a TWKB geometry and writing it back as EWKB:

use postgis::twkb;
use postgis::LineString;

for row in &conn.query("SELECT ST_AsTWKB(route) FROM busline", &[]).unwrap() {
    let route: twkb::LineString = row.get(0);
    let last_stop = route.points().last().unwrap();
    let _ = conn.execute("INSERT INTO stops (stop) VALUES ($1)", &[&last_stop.as_ewkb()]);
}

Unit tests

Unit tests which need a PostgreSQL connection are ignored by default. To run the database tests, declare the connection in an environment variable DBCONN. Example:

export DBCONN=postgresql://user@localhost/testdb

Run the tests with

cargo test -- --ignored

Serialization with serde

This crate provides optional support for serializing and deserializing geometry types using serde. To enable this feature, add the following to your Cargo.toml:

[dependencies]
postgis = { version = "0.9.0", features = ["serde"] }

With this feature enabled, all geometry types in ewkb and twkb modules will implement Serialize and Deserialize traits:

use postgis::ewkb::Point;
use serde_json;

let point = Point {
    x: 1.0,
    y: 2.0,
    srid: Some(4326),
};

// Serialize to JSON
let json = serde_json::to_string(&point).unwrap();
println!("{}", json);

// Deserialize from JSON
let deserialized: Point = serde_json::from_str(&json).unwrap();