Order of accessing my objects

help
1

Hi, newbie here. I'm trying to build a server web using tokio, hyper, routerify and redis.

In a route function, I'm accessing the redis::Client using routerify::RouterBuilder::data and getting the body with hyper::body::to_bytes

Here is my code:

pub async fn handler(req: Request<Body>) -> Result<Response<Body>, Infallible> {
    let state = req.data::<redis::Client>().unwrap();
    let mut conn = redis::aio::ConnectionManager::new(state.clone()).await.unwrap();
    let body = hyper::body::to_bytes(req.into_body());
    // do something with body

And it's working like that.

But my concern is:
I need to check if the body is well formatted and if not, I would like to avoid the connection to redis.

I simply (newbily) thought I just need to read the body before connecting to redis, but computer says no.
I understand that hyper::Request::into_body as taking the ownership, and that's cool.
So I try different things by swapping these 3 lines around and following the errors one by one like a monkey typing on a typewriter.

What am I missing here?

2

You absolutely can just read the body as the first thing. I don't think that in itself is a problem. What error are you exactly getting?

3

If you call req.data() after calling req.into_body(), you'll get an error that req can no longer be used because the value has been moved out of it.

You can avoid this by using req.body_mut() instead of into_body.

1 Like
4

If I read the body with req.into_body(), I got an error when getting the redis client with req.data:: with the message:
borrow of moved value: req

5

I'm getting two errors:

  1. cannot borrow req as mutable, as it is not declared as mutable
  2. cannot borrow req as immutable because it is also borrowed as mutable
6

Please post the code that gave that error along with the full error.

1 Like
7 
pub async fn handler(mut req: Request<Body>) -> Result<Response<Body>, Infallible> {
    let body = hyper::body::to_bytes(req.body_mut());
    let state = req.data::<redis::Client>().unwrap();
    let mut conn = ConnectionManager::new(state.clone()).await.unwrap();

15 |     let body = hyper::body::to_bytes(req.body_mut());
   |                                      --- mutable borrow occurs here

18 |     let state = req.data::<redis::Client>().unwrap();
   |                 ^^^ immutable borrow occurs here
8

That is not the full error. Don't strip context

2 Likes
9

It seems like you're missing an await.

But yes, please do not remove stuff from errors. They're a lot more useful if you include the full error.

1 Like
10

Ok, I understand:


error[E0502]: cannot borrow `req` as immutable because it is also borrowed as mutable
  --> src/mobile/add_friend.rs:18:17
   |
15 |     let body = hyper::body::to_bytes(req.body_mut());
   |                                      --- mutable borrow occurs here
...
18 |     let state = req.data::<redis::Client>().unwrap();
   |                 ^^^ immutable borrow occurs here
...
54 | }
   | - mutable borrow might be used here, when `body` is dropped and runs the destructor for type `impl Future`
1 Like
11

It's seems true (on the body var), I will investigates.

12

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