Rust: Redis のデータを作成 (Create)

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

[package]
name = "redis_create"
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"

// --------------------------------------------------------------------
/*
    redis_create/src/main.rs

                    Jul/22/2020
*/
// --------------------------------------------------------------------
extern crate redis;
use redis::{Commands};
use serde_json::json;
use std::collections::HashMap;

// --------------------------------------------------------------------
fn unit_prepare_proc (name:&'static str,population: i32,date_mod:&'static str) -> String {
    let obj_new = json!({
        "name": name,
        "population": population,
        "date_mod": date_mod
        });

    let json_str = obj_new.to_string();

    return json_str.to_string();
}

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


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

    let mut dict_aa:HashMap<String,String> = HashMap::new();

    let mut json_str = unit_prepare_proc ("福井",53921,"1956-6-9");
    dict_aa.insert("t1851".to_string(),json_str);

    json_str = unit_prepare_proc ("敦賀",82154,"1956-3-4");
    dict_aa.insert("t1852".to_string(),json_str);

    json_str = unit_prepare_proc ("小浜",82157,"1956-10-17");
    dict_aa.insert("t1853".to_string(),json_str);

    json_str = unit_prepare_proc ("大野",13594,"1956-2-21");
    dict_aa.insert("t1854".to_string(),json_str);

    json_str = unit_prepare_proc ("勝山",52836,"1956-12-7");
    dict_aa.insert("t1855".to_string(),json_str);

    json_str = unit_prepare_proc ("鯖江",89132,"1956-10-17");
    dict_aa.insert("t1856".to_string(),json_str);

    json_str = unit_prepare_proc ("あわら",35126,"1956-8-25");
    dict_aa.insert("t1857".to_string(),json_str);

    json_str = unit_prepare_proc ("越前",56923,"1956-4-8");
    dict_aa.insert("t1858".to_string(),json_str);

    json_str = unit_prepare_proc ("坂井",18274,"1956-7-10");
    dict_aa.insert("t1859".to_string(),json_str);

    for (key,value) in &dict_aa {
        let _: ()  = conn.set(key.to_string(), value).unwrap();
        }

    eprintln! ("*** 終了 ***");

    Ok(())
}

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

cargo build

cargo run