#[macro_use]
extern crate rocket;

type Session<'a> = rocket_session::Session<'a, u64>;

#[launch]
fn rocket() -> _ {
    rocket::build()
        .attach(Session::fairing())
        .mount("/", routes![index])
}

#[get("/")]
fn index(session: Session) -> String {
    let count = session.tap(|n| {
        // Change the stored value (it is &mut)
        *n += 1;

        // Return something to the caller.
        // This can be any type, 'tap' is generic.
        *n
    });

    format!("{} visits", count)
}

通过特质扩展会话

.tap() 方法功能强大，但有时您可能希望有更方便的方法。

以下是一个使用自定义特性和 json_dotpath 包来基于 serde 序列化实现多态存储的示例。

请注意，如果您在每个请求中多次访问会话对象，这种方法可能会导致数据竞争，因为每个方法都包含它自己的 .tap()。可能更安全的是在单个共享闭包中手动调用 .dot_*() 方法。

use serde_json::Value;
use serde::de::DeserializeOwned;
use serde::Serialize;
use json_dotpath::DotPaths;

pub type Session<'a> = rocket_session::Session<'a, serde_json::Map<String, Value>>;

pub trait SessionAccess {
    fn get<T: DeserializeOwned>(&self, path: &str) -> Option<T>;

    fn take<T: DeserializeOwned>(&self, path: &str) -> Option<T>;

    fn replace<O: DeserializeOwned, N: Serialize>(&self, path: &str, new: N) -> Option<O>;

    fn set<T: Serialize>(&self, path: &str, value: T);

    fn remove(&self, path: &str) -> bool;
}

impl<'a> SessionAccess for Session<'a> {
    fn get<T: DeserializeOwned>(&self, path: &str) -> Option<T> {
        self.tap(|data| data.dot_get(path))
    }

    fn take<T: DeserializeOwned>(&self, path: &str) -> Option<T> {
        self.tap(|data| data.dot_take(path))
    }

    fn replace<O: DeserializeOwned, N: Serialize>(&self, path: &str, new: N) -> Option<O> {
        self.tap(|data| data.dot_replace(path, new))
    }

    fn set<T: Serialize>(&self, path: &str, value: T) {
        self.tap(|data| data.dot_set(path, value));
    }

    fn remove(&self, path: &str) -> bool {
        self.tap(|data| data.dot_remove(path))
    }
}