Add a separate trait for optional extractors

axum-core/src/extract/mod.rs

@@ -13,11 +13,16 @@ pub mod rejection;
 
 mod default_body_limit;
 mod from_ref;
+mod option;
 mod request_parts;
 mod tuple;
 
 pub(crate) use self::default_body_limit::DefaultBodyLimitKind;
-pub use self::{default_body_limit::DefaultBodyLimit, from_ref::FromRef};
+pub use self::{
+    default_body_limit::DefaultBodyLimit,
+    from_ref::FromRef,
+    option::{OptionalFromRequest, OptionalFromRequestParts},
+};
 
 /// Type alias for [`http::Request`] whose body type defaults to [`Body`], the most common body
 /// type used with axum.
@@ -99,35 +104,6 @@ where
     }
 }
 
-#[async_trait]
-impl<S, T> FromRequestParts<S> for Option<T>
-where
-    T: FromRequestParts<S>,
-    S: Send + Sync,
-{
-    type Rejection = Infallible;
-
-    async fn from_request_parts(
-        parts: &mut Parts,
-        state: &S,
-    ) -> Result<Option<T>, Self::Rejection> {
-        Ok(T::from_request_parts(parts, state).await.ok())
-    }
-}
-
-#[async_trait]
-impl<S, T> FromRequest<S> for Option<T>
-where
-    T: FromRequest<S>,
-    S: Send + Sync,
-{
-    type Rejection = Infallible;
-
-    async fn from_request(req: Request, state: &S) -> Result<Option<T>, Self::Rejection> {
-        Ok(T::from_request(req, state).await.ok())
-    }
-}
-
 #[async_trait]
 impl<S, T> FromRequestParts<S> for Result<T, T::Rejection>
 where

axum-core/src/extract/option.rs

@@ -0,0 +1,60 @@
+use async_trait::async_trait;
+use http::request::Parts;
+
+use crate::response::IntoResponse;
+
+use super::{private, FromRequest, FromRequestParts, Request};
+
+/// TODO: DOCS
+#[async_trait]
+pub trait OptionalFromRequestParts<S>: Sized {
+    /// If the extractor fails it'll use this "rejection" type. A rejection is
+    /// a kind of error that can be converted into a response.
+    type Rejection: IntoResponse;
+
+    /// Perform the extraction.
+    async fn from_request_parts(
+        parts: &mut Parts,
+        state: &S,
+    ) -> Result<Option<Self>, Self::Rejection>;
+}
+
+/// TODO: DOCS
+#[async_trait]
+pub trait OptionalFromRequest<S, M = private::ViaRequest>: Sized {
+    /// If the extractor fails it'll use this "rejection" type. A rejection is
+    /// a kind of error that can be converted into a response.
+    type Rejection: IntoResponse;
+
+    /// Perform the extraction.
+    async fn from_request(req: Request, state: &S) -> Result<Option<Self>, Self::Rejection>;
+}
+
+#[async_trait]
+impl<S, T> FromRequestParts<S> for Option<T>
+where
+    T: OptionalFromRequestParts<S>,
+    S: Send + Sync,
+{
+    type Rejection = T::Rejection;
+
+    async fn from_request_parts(
+        parts: &mut Parts,
+        state: &S,
+    ) -> Result<Option<T>, Self::Rejection> {
+        T::from_request_parts(parts, state).await
+    }
+}
+
+#[async_trait]
+impl<S, T> FromRequest<S> for Option<T>
+where
+    T: OptionalFromRequest<S>,
+    S: Send + Sync,
+{
+    type Rejection = T::Rejection;
+
+    async fn from_request(req: Request, state: &S) -> Result<Option<T>, Self::Rejection> {
+        T::from_request(req, state).await
+    }
+}

axum-extra/src/extract/mod.rs

@@ -19,7 +19,9 @@ mod query;
 #[cfg(feature = "multipart")]
 pub mod multipart;
 
-pub use self::{cached::Cached, optional_path::OptionalPath, with_rejection::WithRejection};
+#[allow(deprecated)]
+pub use self::optional_path::OptionalPath;
+pub use self::{cached::Cached, with_rejection::WithRejection};
 
 #[cfg(feature = "cookie")]
 pub use self::cookie::CookieJar;
@@ -34,7 +36,10 @@ pub use self::cookie::SignedCookieJar;
 pub use self::form::{Form, FormRejection};
 
 #[cfg(feature = "query")]
-pub use self::query::{OptionalQuery, OptionalQueryRejection, Query, QueryRejection};
+#[allow(deprecated)]
+pub use self::query::OptionalQuery;
+#[cfg(feature = "query")]
+pub use self::query::{OptionalQueryRejection, Query, QueryRejection};
 
 #[cfg(feature = "multipart")]
 pub use self::multipart::Multipart;

axum-extra/src/extract/optional_path.rs

@@ -1,6 +1,6 @@
 use axum::{
     async_trait,
-    extract::{path::ErrorKind, rejection::PathRejection, FromRequestParts, Path},
+    extract::{rejection::PathRejection, FromRequestParts, Path},
     RequestPartsExt,
 };
 use serde::de::DeserializeOwned;
@@ -32,9 +32,11 @@ use serde::de::DeserializeOwned;
 ///     .route("/blog/:page", get(render_blog));
 /// # let app: Router = app;
 /// ```
+#[deprecated = "Use Option<Path<_>> instead"]
 #[derive(Debug)]
 pub struct OptionalPath<T>(pub Option<T>);
 
+#[allow(deprecated)]
 #[async_trait]
 impl<T, S> FromRequestParts<S> for OptionalPath<T>
 where
@@ -47,19 +49,15 @@ where
         parts: &mut http::request::Parts,
         _: &S,
     ) -> Result<Self, Self::Rejection> {
-        match parts.extract::<Path<T>>().await {
-            Ok(Path(params)) => Ok(Self(Some(params))),
-            Err(PathRejection::FailedToDeserializePathParams(e))
-                if matches!(e.kind(), ErrorKind::WrongNumberOfParameters { got: 0, .. }) =>
-            {
-                Ok(Self(None))
-            }
-            Err(e) => Err(e),
-        }
+        parts
+            .extract::<Option<Path<T>>>()
+            .await
+            .map(|opt| Self(opt.map(|Path(x)| x)))
     }
 }
 
 #[cfg(test)]
+#[allow(deprecated)]
 mod tests {
     use std::num::NonZeroU32;
 

axum-extra/src/extract/query.rs

@@ -1,6 +1,6 @@
 use axum::{
     async_trait,
-    extract::FromRequestParts,
+    extract::{FromRequestParts, OptionalFromRequestParts},
     response::{IntoResponse, Response},
     Error,
 };
@@ -71,6 +71,28 @@ where
     }
 }
 
+#[async_trait]
+impl<T, S> OptionalFromRequestParts<S> for Query<T>
+where
+    T: DeserializeOwned,
+    S: Send + Sync,
+{
+    type Rejection = QueryRejection;
+
+    async fn from_request_parts(
+        parts: &mut Parts,
+        _state: &S,
+    ) -> Result<Option<Self>, Self::Rejection> {
+        if let Some(query) = parts.uri.query() {
+            let value = serde_html_form::from_str(query)
+                .map_err(|err| QueryRejection::FailedToDeserializeQueryString(Error::new(err)))?;
+            Ok(Some(Self(value)))
+        } else {
+            Ok(None)
+        }
+    }
+}
+
 axum_core::__impl_deref!(Query);
 
 /// Rejection used for [`Query`].
@@ -152,9 +174,11 @@ impl std::error::Error for QueryRejection {
 ///
 /// [example]: https://github.com/tokio-rs/axum/blob/main/examples/query-params-with-empty-strings/src/main.rs
 #[cfg_attr(docsrs, doc(cfg(feature = "query")))]
+#[deprecated = "Use Option<Path<_>> instead"]
 #[derive(Debug, Clone, Copy, Default)]
 pub struct OptionalQuery<T>(pub Option<T>);
 
+#[allow(deprecated)]
 #[async_trait]
 impl<T, S> FromRequestParts<S> for OptionalQuery<T>
 where
@@ -175,6 +199,7 @@ where
     }
 }
 
+#[allow(deprecated)]
 impl<T> std::ops::Deref for OptionalQuery<T> {
     type Target = Option<T>;
 
@@ -184,6 +209,7 @@ impl<T> std::ops::Deref for OptionalQuery<T> {
     }
 }
 
+#[allow(deprecated)]
 impl<T> std::ops::DerefMut for OptionalQuery<T> {
     #[inline]
     fn deref_mut(&mut self) -> &mut Self::Target {
@@ -231,6 +257,7 @@ impl std::error::Error for OptionalQueryRejection {
 }
 
 #[cfg(test)]
+#[allow(deprecated)]
 mod tests {
     use super::*;
     use crate::test_helpers::*;

axum-extra/src/typed_header.rs

@@ -2,7 +2,7 @@
 
 use axum::{
     async_trait,
-    extract::FromRequestParts,
+    extract::{FromRequestParts, OptionalFromRequestParts},
     response::{IntoResponse, IntoResponseParts, Response, ResponseParts},
 };
 use headers::{Header, HeaderMapExt};
@@ -80,6 +80,31 @@ where
     }
 }
 
+#[async_trait]
+impl<T, S> OptionalFromRequestParts<S> for TypedHeader<T>
+where
+    T: Header,
+    S: Send + Sync,
+{
+    type Rejection = TypedHeaderRejection;
+
+    async fn from_request_parts(
+        parts: &mut Parts,
+        _state: &S,
+    ) -> Result<Option<Self>, Self::Rejection> {
+        let mut values = parts.headers.get_all(T::name()).iter();
+        let is_missing = values.size_hint() == (0, Some(0));
+        match T::decode(&mut values) {
+            Ok(res) => Ok(Some(Self(res))),
+            Err(_) if is_missing => Ok(None),
+            Err(err) => Err(TypedHeaderRejection {
+                name: T::name(),
+                reason: TypedHeaderRejectionReason::Error(err),
+            }),
+        }
+    }
+}
+
 axum_core::__impl_deref!(TypedHeader);
 
 impl<T> IntoResponseParts for TypedHeader<T>

axum-macros/tests/debug_handler/fail/argument_not_extractor.stderr

@@ -15,7 +15,7 @@ error[E0277]: the trait bound `bool: FromRequestParts<()>` is not satisfied
             <Version as FromRequestParts<S>>
             <Extensions as FromRequestParts<S>>
             <ConnectInfo<T> as FromRequestParts<S>>
-          and $N others
+          and 28 others
   = note: required for `bool` to implement `FromRequest<(), axum_core::extract::private::ViaParts>`
 note: required by a bound in `__axum_macros_check_handler_0_from_request_check`
  --> tests/debug_handler/fail/argument_not_extractor.rs:5:24

axum-macros/tests/debug_handler/fail/json_not_deserialize.stderr

@@ -13,7 +13,7 @@ error[E0277]: the trait bound `for<'de> Struct: serde::de::Deserialize<'de>` is
             i32
             i64
             i128
-          and $N others
+          and 131 others
   = note: required for `Struct` to implement `serde::de::DeserializeOwned`
   = note: required for `Json<Struct>` to implement `FromRequest<()>`
   = help: see issue #48214

axum-macros/tests/debug_handler/fail/single_wrong_return_tuple.stderr

@@ -10,10 +10,10 @@ error[E0277]: the trait bound `NotIntoResponse: IntoResponse` is not satisfied
             axum::body::Bytes
             Body
             axum::extract::rejection::FailedToBufferBody
+            bytes::bytes_mut::BytesMut
             axum::extract::rejection::LengthLimitError
             axum::extract::rejection::UnknownBodyError
-            bytes::bytes_mut::BytesMut
-          and $N others
+          and 121 others
 note: required by a bound in `__axum_macros_check_handler_into_response::{closure#0}::check`
  --> tests/debug_handler/fail/single_wrong_return_tuple.rs:6:23
   |

axum-macros/tests/debug_handler/fail/wrong_return_tuple.stderr

@@ -19,6 +19,6 @@ error[E0277]: the trait bound `CustomIntoResponse: IntoResponseParts` is not sat
              [(K, V); N]
              ()
              (T1,)
-           and $N others
+           and 15 others
    = help: see issue #48214
    = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable

axum-macros/tests/debug_handler/fail/wrong_return_type.stderr

@@ -10,10 +10,10 @@ error[E0277]: the trait bound `bool: IntoResponse` is not satisfied
             axum::body::Bytes
             Body
             axum::extract::rejection::FailedToBufferBody
+            bytes::bytes_mut::BytesMut
             axum::extract::rejection::LengthLimitError
             axum::extract::rejection::UnknownBodyError
-            bytes::bytes_mut::BytesMut
-          and $N others
+          and 121 others
 note: required by a bound in `__axum_macros_check_handler_into_response::{closure#0}::check`
  --> tests/debug_handler/fail/wrong_return_type.rs:4:23
   |

axum-macros/tests/from_request/fail/generic_without_via.stderr

@@ -5,23 +5,23 @@ error: #[derive(FromRequest)] only supports generics when used with #[from_reque
   |                  ^
 
 error[E0277]: the trait bound `fn(Extractor<()>) -> impl Future<Output = ()> {foo}: Handler<_, _>` is not satisfied
-  --> tests/from_request/fail/generic_without_via.rs:11:44
-   |
-11 |     _ = Router::<()>::new().route("/", get(foo));
-   |                                        --- ^^^ the trait `Handler<_, _>` is not implemented for fn item `fn(Extractor<()>) -> impl Future<Output = ()> {foo}`
-   |                                        |
-   |                                        required by a bound introduced by this call
-   |
-   = note: Consider using `#[axum::debug_handler]` to improve the error message
-   = help: the following other types implement trait `Handler<T, S>`:
-             <Layered<L, H, T, S> as Handler<T, S>>
-             <MethodRouter<S> as Handler<(), S>>
+   --> tests/from_request/fail/generic_without_via.rs:11:44
+    |
+11  |     _ = Router::<()>::new().route("/", get(foo));
+    |                                        --- ^^^ the trait `Handler<_, _>` is not implemented for fn item `fn(Extractor<()>) -> impl Future<Output = ()> {foo}`
+    |                                        |
+    |                                        required by a bound introduced by this call
+    |
+    = note: Consider using `#[axum::debug_handler]` to improve the error message
+    = help: the following other types implement trait `Handler<T, S>`:
+              <Layered<L, H, T, S> as Handler<T, S>>
+              <MethodRouter<S> as Handler<(), S>>
 note: required by a bound in `axum::routing::get`
-  --> $WORKSPACE/axum/src/routing/method_routing.rs
-   |
-   | top_level_handler_fn!(get, GET);
-   | ^^^^^^^^^^^^^^^^^^^^^^---^^^^^^
-   | |                     |
-   | |                     required by a bound in this function
-   | required by this bound in `get`
-   = note: this error originates in the macro `top_level_handler_fn` (in Nightly builds, run with -Z macro-backtrace for more info)
+   --> $WORKSPACE/axum/src/routing/method_routing.rs
+    |
+    | top_level_handler_fn!(get, GET);
+    | ^^^^^^^^^^^^^^^^^^^^^^---^^^^^^
+    | |                     |
+    | |                     required by a bound in this function
+    | required by this bound in `get`
+    = note: this error originates in the macro `top_level_handler_fn` (in Nightly builds, run with -Z macro-backtrace for more info)