如何在Rust中合并来自不同库的类型？

Question

I am using the the Rust libraries swtweb (to interface with JavaScript) and serde-json (to work with JSON). Both have a Value type to represent JavaScript objects that are very similar:

swtweb's Value :

#[derive(Clone, PartialEq, Debug)]
pub enum Value {
    Undefined,
    Null,
    Bool(bool),
    Number(Number),
    Symbol(Symbol),
    String(String),
    Reference(Reference)
}

and serde-json's Value :

#[derive(Clone, PartialEq)]
pub enum Value {
    Null,
    Bool(bool),
    Number(Number),
    String(String),
    Array(Vec<Value>),
    Object(Map<String, Value>),
}

What is an approach to transform instances of one type to another? Is it possible to derive a common trait without modifying the libraries?

Answer 1

Looking at the doc of stdweb::Value , it seems they have you covered!

It implements TryFrom<JsonValue> , with JsonValue being an alias of serde_json::Value , so this lets you converts from serde_json::Value to stdweb::Value .

It implements Serialize , and serde_json::to_value lets you convert any type that implements Serialize to a serde_json::Value

So this should work:

let json_value: serde_json::Value = json!("my value");
println!("{:#?}", json_value);

let stdweb_value: stdweb::Value = stdweb::Value::try_from(json_value).unwrap();
println!("{:#?}", stdweb_value);

let json_value_again: serde_json::Value = serde_json::to_value(stdweb_value).unwrap();
println!("{:#?}", json_value_again);