example_projects/serde_json_test/src/main.rs

use std::collections::HashMap;

use serde::Serialize;
use serde_with::serde_as;

#[derive(Debug, Eq, PartialEq, Hash, Clone, Serialize)]
struct Path(pub Vec<u32>);

#[derive(Serialize)]
struct Rel {
    path: Path,
    count: usize,
}

#[serde_as]
#[derive(Serialize)]
struct Cl1 {
    #[serde_as(as = "Vec<(_, _)>")]
    cache: HashMap<Vec<u32>, String>,
}

type RelCache = HashMap<Path, Rel>;
#[serde_as]
#[derive(Serialize)]
struct Cl2 {
    #[serde_as(as = "Vec<(_, _)>")]
    cache: RelCache,
}

fn main() {
    let mut cache = HashMap::new();
    cache.insert(vec![1, 2, 3], "Erster Eintrag".to_owned());
    cache.insert(vec![4, 5, 6], "Zweiter Eintrag".to_owned());
    let cl = Cl1 {
        cache
    };
    let json = serde_json::to_string(&cl);
    dbg!(json);

    let path1 = Path(vec![1, 2, 3]);
    let path2 = Path(vec![4, 5, 6]);
    let rel1 = Rel {
        path: path1.clone(),
        count: 37,
    };
    let rel2 = Rel {
        path: path2.clone(),
        count: 87,
    };
    let mut cache = RelCache::new();
    cache.insert(path1, rel1);
    cache.insert(path2, rel2);
    let cl = Cl2 {
        cache
    };

    let json = serde_json::to_string(&cl);
    dbg!(json);
}