Simpler endpoint return type

[jayvdb]

My team is using actix_default_responder::JsonResponder from https://github.com/jsam/actix-default-responder because it allows our Rust docs to explicitly (and clearly) state what the HTTP response value is.

#[derive(Clone, Debug, Default, Deserialize, Dummy, PartialEq, Serialize, actix_default_responder::JsonResponder, utoipa::ToSchema)]
pub struct Foo {
    ...
}

#[get("/return_foo")]
async fn return_foo() -> Result<Foo, actix_web::Error> {
    let foo: Foo = Faker.fake();
    foo
}

This return type should be easily consumed by utoipa to automatically pre-populate the responses for the '20x' case.

We haven't adopted the utoipa IntoResponse because it would force us to push all of the errors into a utoipa compliant error system, and also means the return value doesnt directly link to the struct of the returned response.

While our approach works for us, and we're actix only, perhaps there is a middle ground where utoipa provides actix-default-responder-like solution that is generic, meaning it only handles the 20x side of the Result, with a simple attribute to indicate which 20x to use.

Just an idea as I see #589 and #582 improving IntoResponse and I am wishing we were able to use these lovely features... ;-)

[juhaku]

Actually this is my end goal to have a support for at least partially to the default responses for actix_web, axum and perhaps rocket as well. Current idea is that responses should primarily implement IntoResponses (or other such trait if I get to create a new one) to describe the possible responses. But if the reponse returns something like Result<T, E> then T should become 200 response, and E will become so called "default" response. But let's see what is possible and how things turn out to be. 😄

I am wishing we were able to use these lovely features... ;-)

I am hoping to get these implemented asap, but this needs some amount of testing because of it requires deeper undestanding of internals of framework at hand and that is a bit time consuming.