Rust JSON formats

rust-json.md

Be able to parse the following JSON format:

{
  "token": "ASDSD",
  "action": "Foo",
  "payload": {},
}

Where token maps to a uuid::Uuid (got this) and action maps to an ActionType enum (got this, but very verbose).

The tricky part is mapping payload to predefined structs (there's a lot of them). Some examples are:

#[derive(RustcDecodable, Debug)]
pub struct IncomingMessage<T> {
    pub token: Uuid,
    pub action: ActionType,
    pub payload: Option<T>,
}

pub struct AuthenticatePayload {
    pub id: u64,
    pub name: String,
}

pub struct MessageUserPayload {
    pub user: u64,
    pub message: String,
}

That certainly is a lot of boilerplate. You might want to try something like I did in my hal library. You can map the json to key/value pairs doing something like this: https://github.com/hjr3/hal-rs/blob/master/src/resource.rs#L11 and then define a sum type (enum) for all the different data types: https://github.com/hjr3/hal-rs/blob/master/src/state.rs. I was going from types -> json, but you can write a custom deserializer to do the opposite. It would mean you would need to constantly destructure the value though.

All that being said, the Rust type system is going to make you be explicit at some point.

@hjr3 Yeah it's definitely a hard problem to solve when trying to avoid being super explicit. Was trying to make use of rustc-serialize's automatic decoding, but have had no luck targeting nested objects directly. Will look into your approach.