Rust: Redis のデータを更新 (Update)

フォルダー構造

$ tree -L 2
.
├── Cargo.lock
├── Cargo.toml
├── src
│   └── main.rs
└── target
    └── debug

Cargo.toml

[package]
name = "redis_update"
version = "0.1.0"
edition = "2018"

#

[dependencies.redis]
version = "*"

[dependencies]
tokio = { version = "0.2", features = ["full"] }
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0"
chrono = "0.4"

src/main.rs

// --------------------------------------------------------------------
/*
	redis_update/src/main.rs

					Jul/22/2020
*/
// --------------------------------------------------------------------
use std::env;
extern crate redis;
use redis::{Commands};
use chrono::{Local, Date};
use serde_json::json;

// --------------------------------------------------------------------
fn main() -> Result<(), Box<dyn std::error::Error>>  {
	eprintln! ("*** 開始 ***");

	let args: Vec<_> = env::args().collect();
	let key_in = &args[1];
	let population_in = &args[2];
	println! ("{}\t{}",key_in,population_in);

	let client = redis::Client::open("redis://localhost/").expect("url error");
	let mut conn = client.get_connection().expect("connect error");

	let res = conn.get(key_in.to_string());

	let answer: String = res.unwrap();

	let json: serde_json::Value = serde_json::from_str(&answer)?;

	let obj = json.as_object().unwrap();

	println! ("{}",obj["name"].to_string());
	println! ("{}",obj["population"].to_string());
	println! ("{}",obj["date_mod"].to_string());

	let date_mod: Date<Local> = Local::today();
	println!("{}", date_mod);

	let pp_in : i32 = population_in.parse().unwrap();
	let obj_new = json!({
		"name": obj["name"],
		"population": pp_in,
		"date_mod": date_mod.to_string()
		});

	let json_str = obj_new.to_string();
	println!("{}",json_str);

	let _: ()  = conn.set(key_in.to_string(), json_str).unwrap();

	eprintln! ("*** 終了 ***");

	Ok(())
}

// --------------------------------------------------------------------

コンパイル

cargo build

実行

cargo run t1857 5128900