是否有推荐的方法来修改 actix-web 上收到的请求？我正在寻找将数据添加到请求对象并使其可供下游中间件和处理程序处理的方法。
The 中间件文档 https://actix.rs/docs/middleware/ says:
“Actix-web 的中间件系统允许我们为请求/响应处理添加额外的行为。中间件可以挂钩传入的请求流程，使我们能够修改请求以及停止请求处理以尽早返回响应。”
该页面没有有关如何修改请求的示例。
让我们看下面的代码（从上面的文档中获得），以某种方式向请求添加数据的代码是什么？
use std::pin::Pin;
use std::task::{Context, Poll};
use actix_service::{Service, Transform};
use actix_web::{dev::ServiceRequest, dev::ServiceResponse, Error};
use futures::future::{ok, Ready};
use futures::Future;
// There are two steps in middleware processing.
// 1. Middleware initialization, middleware factory gets called with
// next service in chain as parameter.
// 2. Middleware's call method gets called with normal request.
pub struct SayHi;
// Middleware factory is `Transform` trait from actix-service crate
// `S` - type of the next service
// `B` - type of response's body
impl<S, B> Transform<S> for SayHi
where
S: Service<Request = ServiceRequest, Response = ServiceResponse<B>, Error = Error>,
S::Future: 'static,
B: 'static,
{
type Request = ServiceRequest;
type Response = ServiceResponse<B>;
type Error = Error;
type InitError = ();
type Transform = SayHiMiddleware<S>;
type Future = Ready<Result<Self::Transform, Self::InitError>>;
fn new_transform(&self, service: S) -> Self::Future {
ok(SayHiMiddleware { service })
}
}
pub struct SayHiMiddleware<S> {
service: S,
}
impl<S, B> Service for SayHiMiddleware<S>
where
S: Service<Request = ServiceRequest, Response = ServiceResponse<B>, Error = Error>,
S::Future: 'static,
B: 'static,
{
type Request = ServiceRequest;
type Response = ServiceResponse<B>;
type Error = Error;
type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>>>>;
fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
self.service.poll_ready(cx)
}
fn call(&mut self, req: ServiceRequest) -> Self::Future {
println!("Hi from start. You requested: {}", req.path());
let fut = self.service.call(req);
Box::pin(async move {
let res = fut.await?;
println!("Hi from response");
Ok(res)
})
}
}
