example_projects/serde_json_test/src/main.rs

use std::collections::HashMap;

use serde::{Serialize, Deserialize};
use serde_with::serde_as;

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

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

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

type RelCache = HashMap<Path, Rel>;
#[serde_as]
#[derive(Serialize, Deserialize, Debug)]
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).unwrap();
    dbg!(&json);
    let obj: Cl2 = serde_json::from_str(&json).unwrap();
    dbg!(obj);
}

/// Output:
///
/// [src/main.rs:58] &json = "{\"cache\":[[[4,5,6],{\"path\":[4,5,6],\"count\":87}],[[1,2,3],{\"path\":[1,2,3],\"count\":37}]]}"
/// [src/main.rs:60] obj = Cl2 {
///     cache: {
///         Path(
///             [
///                 1,
///                 2,
///                 3,
///             ],
///         ): Rel {
///             path: Path(
///                 [
///                     1,
///                     2,
///                     3,
///                 ],
///             ),
///             count: 37,
///         },
///         Path(
///             [
///                 4,
///                 5,
///                 6,
///             ],
///         ): Rel {
///             path: Path(
///                 [
///                     4,
///                     5,
///                     6,
///                 ],
///             ),
///             count: 87,
///         },
///     },
/// }