How to modify the Payload of ServiceRequest in custom middleware

[new-commer]

I want to modify the Payload of ServiceRequest in function call, and do not how to do

impl<S> Service for CheckerMiddleware<S>
where
    S: Service<Request = ServiceRequest, Response = ServiceResponse, Error = actix_web::Error>,
    S::Future: 'static,
    S: 'static,
{
    type Request = ServiceRequest;
    type Response = ServiceResponse;
    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.borrow_mut().poll_ready(cx)
    }

    fn call(&mut self, req: S::Request) -> Self::Future {
        //1.get payload
        let (req, payload) = req.into_parts();
        //2. convert payload to json
        let s = web::Json::<String>::from_request(&req, &mut payload).await.unwrap();
        let mut v: serde_json::Value = serde_json::from_str(&s).unwrap();
        //3. modify json value
        v["v1"] = "test";
        //4. convert v to payload(do not know how to do)
        let new_payload = ?
        let req = ServiceRequest::from_request(req).map(|req| req.set_payload(new_payload ))?;
        self.service.call(req)
    }
}

[new-commer]

I guarantee payload is JSON data.

[robjtede]

There's a trick we use internally for it in the Either extractor:

fn payload_from_bytes(bytes: Bytes) -> dev::Payload {
    let (_, mut h1_payload) = actix_http::h1::Payload::create(true);
    h1_payload.unread_data(bytes);
    dev::Payload::from(h1_payload)
}

[new-commer]

@robjtede Thank you very much!