Simple example of using rust-postgres with chrono + chrono date arithmetic and UTC -> local time conversion with UTC dt stored properly in postgres

Cargo.toml

[package]
name = "postgres_test"
version = "0.1.0"
authors = ["Warren Henning <[email protected]>"]
edition = "2018"

[dependencies]
chrono = { version = "0.4", features = ["serde"] }
postgres = { version = "0.15", features = ["with-time", "with-chrono"] }

main.rs

/*
Sample output:

$ cargo run --release
    Finished release [optimized] target(s) in 0.08s                                                                                                                                                                                    
     Running `target/release/postgres_test`
Found person 24: Steven, 2018-10-15 07:28:36.689364 UTC
Found person 24: Steven, 2018-11-14 07:28:36.689364 UTC
Locally, person.last_updated = 2018-11-13 23:28:36.689364 -08:00
*/

extern crate postgres;
extern crate chrono;

use postgres::{Connection, TlsMode};
use chrono::{Duration, DateTime, Utc, Local, TimeZone};

struct Person {
    id: i32,
    name: String,
    last_updated: DateTime<Utc>,
    data: Option<Vec<u8>>,
}

fn insert_person(conn: &Connection, person: &Person) {
    conn.execute("insert into people (name, last_updated, data) values ($1, $2, $3)",
        &[&person.name, &person.last_updated, &person.data]).unwrap();
}

fn save_person(conn: &Connection, person: &Person) {
    assert!(person.id != 0);
    conn.execute("update people set name = $1, last_updated = $2, data = $3 where id = $4",
        &[&person.name, &person.last_updated, &person.data, &person.id]).unwrap();
}

fn main() {
    let conn = Connection::connect("postgres://warren@localhost:5432/arete", TlsMode::None).unwrap();
    conn.execute("CREATE TABLE if not exists people (
                    id              SERIAL PRIMARY KEY,
                    name            VARCHAR NOT NULL,
                    last_updated    timestamp with time zone,
                    data            BYTEA
                  )", &[]).unwrap();
    
    let mut me = Person {
        id: 0,
        name: "Steven".to_string(),
        last_updated: Utc::now(),
        data: None,
    };

    insert_person(&conn, &me);

    for row in &conn.query("SELECT id, name, last_updated, data FROM people order by id desc limit 1", &[]).unwrap() {
        let person = Person {
            id: row.get(0),
            name: row.get(1),
            last_updated: row.get(2),
            data: row.get(3),
        };
        me.id = person.id;
        println!("Found person {}: {}, {}", person.id, person.name, person.last_updated);
    }

    me.last_updated = me.last_updated + Duration::days(30);
    save_person(&conn, &me);

    for row in &conn.query("SELECT id, name, last_updated, data FROM people order by id desc limit 1", &[]).unwrap() {
        let person = Person {
            id: row.get(0),
            name: row.get(1),
            last_updated: row.get(2),
            data: row.get(3),
        };
        println!("Found person {}: {}, {}", person.id, person.name, person.last_updated);
        println!("Locally, person.last_updated = {}", Local.from_utc_datetime(&person.last_updated.naive_utc()));
    }
}