Module serde_with::rust::hashmap_as_tuple_list

👎 Deprecated since 1.8.0:

Use the more general map_as_tuple_list module.

DEPRECATED De/Serialize a HashMap into a list of tuples

Use the map_as_tuple_list module which is more general than this. It should work with everything convertible to and from an Iterator including BTreeMap and HashMap.

---

Some formats, like JSON, have limitations on the type of keys for maps. In case of JSON, keys are restricted to strings. Rust features more powerful keys, for example tuple, which can not be serialized to JSON.

This helper serializes the HashMap into a list of tuples, which does not have the same type restrictions.

If you need to de/serialize a BTreeMap then use btreemap_as_tuple_list.

Converting to serde_as

The same functionality can be more clearly expressed using the serde_as macro. The _ is a placeholder which works for any type which implements Serialize/Deserialize, such as the tuple and u32 type.

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

Examples

#[derive(Deserialize, Serialize)]
struct A {
    #[serde(with = "serde_with::rust::hashmap_as_tuple_list")]
    s: HashMap<(String, u32), u32>,
}

let v: A = serde_json::from_value(json!({
    "s": [
        [["Hello", 123], 0],
        [["World", 456], 1]
    ]
})).unwrap();

assert_eq!(2, v.s.len());
assert_eq!(1, v.s[&("World".to_string(), 456)]);

The helper is generic over the hasher type of the HashMap and works with different variants, such as FnvHashMap.

use fnv::FnvHashMap;

#[derive(Deserialize, Serialize)]
struct A {
    #[serde(with = "serde_with::rust::hashmap_as_tuple_list")]
    s: FnvHashMap<u32, bool>,
}

let v: A = serde_json::from_value(json!({
    "s": [
        [0, false],
        [1, true]
    ]
})).unwrap();

assert_eq!(2, v.s.len());
assert_eq!(true, v.s[&1]);

Functions

deserialize

Deserialize a map from a list of tuples

serialize

Serialize the map as a list of tuples