hyperium / hyperium/http-body

Should `Request<B>` and `Response<B>` implement `Body`?

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#48 3 comments 2 reactions 0 assignees View on GitHub

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Dominant language
Rust
Stars
173
Forks
69
Avg merge
6d 15h
Merged PRs (30d)
4

Description

Today I discovered an unfortunate interaction between axum and http-body.

In axum you're able to write this:

use axum::{
    body::{box_body, Body, BoxBody},
    handler::get,
    http::Response,
    Router,
};

let app = Router::new().route(
    "/",
    get(|| async {
        // Build a response with a header.
        let response: Response<Body> = Response::builder()
            .header("x-foo", "foo")
            .body(Body::empty())
            .unwrap();

        // Since `Response<B>` implements `Body`, we can use `box_body` to
        // convert it into a `BoxBody`.
        let body: BoxBody = box_body(response);

        // And because `BoxBody` implements `IntoResponse` we can return it
        // from handlers.
        //
        // However `impl IntoResponse for BoxBody` simply does
        // `Response::new(self)` thus removing headers, status, etc.
        body
    }),
);

So because Response<B> implements Body it can be used with box_body but that ends up removing everything from the response except the body. I think being able to return bodies directly from axum handlers is a nice feature its just unfortunate that this particular thing compiles.

BoxBody's IntoResponse impl is here.

One could say "well just don't do this" but would be nice if it didn't compile at all, which could be done by removing impl Body for {Response, Request}<B>. Thats of course a breaking change 😞

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reviewing the Body implementations for Request<B> and Response<B>, then inspect the linked axum src/body.rs and src/response/mod.rs references. Determine whether removing those implementations avoids the demonstrated metadata loss and assess the breaking-change impact before deciding what tests or API updates are needed.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
networking
Issue type
Refactor
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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