use std::collections::HashMap;
use serde::{Deserialize, Serialize};
use serde_json::Value;

#[derive(Debug, Deserialize, Serialize)]
pub struct Test {
    a: String,
    b: u64,
    c: Base,
}

#[derive(Debug, Deserialize, Serialize)]
pub struct Base {
    d: u64,
}

fn main() {
    let x = Test { a: "a".to_string(), b: 7, c: Base { d: 1 } };
    println!("before {:?}", x);
    let y = serde_json::to_string(&x).unwrap();

    let mut z: HashMap<String, Value> = serde_json::from_str(&y).unwrap();

    let new_string = "{\"a\": \"b\"}";
    let new: HashMap<String, Value> = serde_json::from_str(&new_string).unwrap();
    z.extend(new);

    let y = serde_json::to_string(&z).unwrap();

    let x: Test = serde_json::from_str(&y).unwrap();
    println!("after  {:?}", x);
}