Please add caching example

[bangbaew]

I want to wrap an in-memory cache middleware for all GET routes that returns 200, the cache key should be based on the full request URL and can be customized, If I send "Cache-Control": "no-cache" in the request headers, Actix should process the request and overwrite the new response in the cache key, and I want the ability to delete the cache key in case of successful data update, so I can get the new data again in the next request.

Thanks.

[bangbaew]

I've tried this:

use actix_http::header::CONTENT_TYPE;
use actix_session::SessionExt;
use actix_web::{
    body::{self, MessageBody},
    dev::{ServiceRequest, ServiceResponse},
    http::{
        header::{HeaderValue, CACHE_CONTROL},
        Method, StatusCode,
    },
    Error, HttpResponse,
};

use actix_web_lab::middleware::Next;

pub async fn cache_middleware(
    req: ServiceRequest,
    next: Next<impl MessageBody>,
) -> Result<ServiceResponse<impl MessageBody>, Error> {
    let key = format!("{}{}", req.path(), req.query_string());
    let session = req.get_session();

    if let Ok(cached_response) = session.get::<String>(&key) {
        //println!("{:?}", cached_response);
        if cached_response.is_some() {
            let res = HttpResponse::new(StatusCode::OK).set_body(cached_response.unwrap());
            let mut res = ServiceResponse::new(req.request().to_owned(), res);

            res.headers_mut()
                .append(CONTENT_TYPE, HeaderValue::from_static("application/json"));
            res.headers_mut()
                .append(CACHE_CONTROL, HeaderValue::from_static("max-age=86400"));

            return Ok(res);
        }
    }
    // Call the next service
    let res = next.call(req).await?;

    // deconstruct response into parts
    let (req, res) = res.into_parts();
    let (res, body) = res.into_parts();

    // Convert body to Bytes
    let body = body::to_bytes(body).await.ok().unwrap();
    // Use bytes directly for caching instead of converting to a String
    let res_body_enc = std::str::from_utf8(&body).unwrap();

    let res = res.set_body(res_body_enc.to_owned());
    let mut res = ServiceResponse::new(req.to_owned(), res);

    println!("{}, {}", req.method(), res.status());
    if req.method() == Method::GET && StatusCode::is_success(&res.status()) {
        println!("caching");
        res.headers_mut()
            .append(CACHE_CONTROL, HeaderValue::from_static("max-age=86400"));
        if let Err(e) = session.insert(key, res_body_enc) {
            println!("cache insert error: {}", e);
        }
    } else {
        println!("not caching");
    }
    Ok(res)
}

it's working fine but i'm not sure if it can be optimized to improve efficiency and performance

[robjtede]

PR welcome where comments on specifics can be made.

[bangbaew]

PR welcome where comments on specifics can be made.

Ok, but I’ll have to fix the problem when redis is not running, it will always return status 500 when session.get() or session.set() is called, the error catch block is not working.

and I’ll have to implement header Cache-Control: no-cache directive in case I want to skip cache.

[bangbaew]

PR welcome where comments on specifics can be made.

Ready for review #630