Fix ServiceExt::handle_error footgun
#120
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As described in #108 (comment), a `HandleError` created from `axum::ServiceExt::handle_error` should _not_ implement `RoutingDsl` as that leads to confusing routing behavior. The technique used here of adding another type parameter to `HandleError` isn't very clean, I think. But the alternative is duplicating `HandleError` and having two versions, which I think is less desirable.
davidpdrsn
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C-enhancement
davidpdrsn
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Aug 8, 2021
Previously, on `main`, this wouldn't compile:
```rust
let app = route("/", get(handler))
.layer(
ServiceBuilder::new()
.timeout(Duration::from_secs(10))
.into_inner(),
)
.handle_error(...)
.route(...); // <-- doesn't work
```
That is because `handle_error` would be
`axum::service::ServiceExt::handle_error` which returns `HandleError<_,
_, _, HandleErrorFromService>` which does _not_ implement `RoutingDsl`.
So you couldn't call `route`. This was caused by
#120.
Basically `handle_error` when called on a `RoutingDsl`, the resulting
service should also implement `RoutingDsl`, but if called on another
random service it should _not_ implement `RoutingDsl`.
I don't think thats possible by having `handle_error` on `ServiceExt`
which is implemented for any service, since all axum routers are also
services by design.
This resolves the issue by removing `ServiceExt` and moving its methods
to `RoutingDsl`. Then we have more tight control over what has a
`handle_error` method.
`service::OnMethod` now also has a `handle_error` so you can still
handle errors from random services, by doing
`service::any(svc).handle_error(...)`.
davidpdrsn
added a commit
that referenced
this pull request
Aug 8, 2021
Previously, on `main`, this wouldn't compile:
```rust
let app = route("/", get(handler))
.layer(
ServiceBuilder::new()
.timeout(Duration::from_secs(10))
.into_inner(),
)
.handle_error(...)
.route(...); // <-- doesn't work
```
That is because `handle_error` would be
`axum::service::ServiceExt::handle_error` which returns `HandleError<_,
_, _, HandleErrorFromService>` which does _not_ implement `RoutingDsl`.
So you couldn't call `route`. This was caused by
#120.
Basically `handle_error` when called on a `RoutingDsl`, the resulting
service should also implement `RoutingDsl`, but if called on another
random service it should _not_ implement `RoutingDsl`.
I don't think thats possible by having `handle_error` on `ServiceExt`
which is implemented for any service, since all axum routers are also
services by design.
This resolves the issue by removing `ServiceExt` and moving its methods
to `RoutingDsl`. Then we have more tight control over what has a
`handle_error` method.
`service::OnMethod` now also has a `handle_error` so you can still
handle errors from random services, by doing
`service::any(svc).handle_error(...)`.
davidpdrsn
added a commit
that referenced
this pull request
Aug 8, 2021
Previously, on `main`, this wouldn't compile:
```rust
let app = route("/", get(handler))
.layer(
ServiceBuilder::new()
.timeout(Duration::from_secs(10))
.into_inner(),
)
.handle_error(...)
.route(...); // <-- doesn't work
```
That is because `handle_error` would be
`axum::service::ServiceExt::handle_error` which returns `HandleError<_,
_, _, HandleErrorFromService>` which does _not_ implement `RoutingDsl`.
So you couldn't call `route`. This was caused by
#120.
Basically `handle_error` when called on a `RoutingDsl`, the resulting
service should also implement `RoutingDsl`, but if called on another
random service it should _not_ implement `RoutingDsl`.
I don't think thats possible by having `handle_error` on `ServiceExt`
which is implemented for any service, since all axum routers are also
services by design.
This resolves the issue by removing `ServiceExt` and moving its methods
to `RoutingDsl`. Then we have more tight control over what has a
`handle_error` method.
`service::OnMethod` now also has a `handle_error` so you can still
handle errors from random services, by doing
`service::any(svc).handle_error(...)`.
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Motivation
As described in #108 (comment), a
HandleErrorcreated fromaxum::ServiceExt::handle_errorshould notimplement
RoutingDslas that leads to confusing routing behavior.Solution
The technique used here of adding another type parameter to
HandleErrorisn't very clean, I think. But the alternative isduplicating
HandleErrorand having two versions, which I think is lessdesirable.