Add a separate trait for optional extractors

axum-core/CHANGELOG.md

@@ -5,6 +5,14 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+# Unreleased
+
+- **breaking:**: `Option<T>` as an extractor now requires `T` to implement the
+  new trait `OptionalFromRequest` (if used as the last extractor) or
+  `OptionalFromRequestParts` (other extractors) ([#2475])
+
+[#2475]: https://github.com/tokio-rs/axum/pull/2475
+
 # 0.5.0
 
 ## alpha.1

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.
@@ -102,33 +107,6 @@ where
     }
 }
 
-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())
-    }
-}
-
-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())
-    }
-}
-
 impl<S, T> FromRequestParts<S> for Result<T, T::Rejection>
 where
     T: FromRequestParts<S>,

axum-core/src/extract/option.rs

@@ -0,0 +1,63 @@
+use std::future::Future;
+
+use http::request::Parts;
+
+use crate::response::IntoResponse;
+
+use super::{private, FromRequest, FromRequestParts, Request};
+
+/// Customize the behavior of `Option<Self>` as a [`FromRequestParts`]
+/// extractor.
+pub trait OptionalFromRequestParts<S>: Sized {
+    /// If the extractor fails, it will use this "rejection" type.
+    ///
+    /// A rejection is a kind of error that can be converted into a response.
+    type Rejection: IntoResponse;
+
+    /// Perform the extraction.
+    fn from_request_parts(
+        parts: &mut Parts,
+        state: &S,
+    ) -> impl Future<Output = Result<Option<Self>, Self::Rejection>> + Send;
+}
+
+/// Customize the behavior of `Option<Self>` as a [`FromRequest`] extractor.
+pub trait OptionalFromRequest<S, M = private::ViaRequest>: Sized {
+    /// If the extractor fails, it will use this "rejection" type.
+    ///
+    /// A rejection is a kind of error that can be converted into a response.
+    type Rejection: IntoResponse;
+
+    /// Perform the extraction.
+    fn from_request(
+        req: Request,
+        state: &S,
+    ) -> impl Future<Output = Result<Option<Self>, Self::Rejection>> + Send;
+}
+
+impl<S, T> FromRequestParts<S> for Option<T>
+where
+    T: OptionalFromRequestParts<S>,
+    S: Send + Sync,
+{
+    type Rejection = T::Rejection;
+
+    fn from_request_parts(
+        parts: &mut Parts,
+        state: &S,
+    ) -> impl Future<Output = Result<Option<T>, Self::Rejection>> {
+        T::from_request_parts(parts, state)
+    }
+}
+
+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/CHANGELOG.md

@@ -7,11 +7,15 @@ and this project adheres to [Semantic Versioning].
 
 # Unreleased
 
+- **breaking:** `Option<Query<T>>` no longer swallows all error conditions, instead rejecting the
+  request in many cases; see its documentation for details ([#2475])
+- **changed:** Deprecated `OptionalPath<T>` and `OptionalQuery<T>` ([#2475])
 - **fixed:** `Host` extractor includes port number when parsing authority ([#2242])
 - **added:** Add `RouterExt::typed_connect` ([#2961])
 - **added:** Add `json!` for easy construction of JSON responses ([#2962])
 
 [#2242]: https://github.com/tokio-rs/axum/pull/2242
+[#2475]: https://github.com/tokio-rs/axum/pull/2475
 [#2961]: https://github.com/tokio-rs/axum/pull/2961
 [#2962]: https://github.com/tokio-rs/axum/pull/2962
 

axum-extra/src/extract/mod.rs

@@ -24,9 +24,9 @@ pub mod multipart;
 #[cfg(feature = "scheme")]
 mod scheme;
 
-pub use self::{
-    cached::Cached, host::Host, optional_path::OptionalPath, with_rejection::WithRejection,
-};
+#[allow(deprecated)]
+pub use self::optional_path::OptionalPath;
+pub use self::{cached::Cached, host::Host, with_rejection::WithRejection};
 
 #[cfg(feature = "cookie")]
 pub use self::cookie::CookieJar;
@@ -41,7 +41,10 @@ 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

@@ -1,5 +1,5 @@
 use axum::{
-    extract::{path::ErrorKind, rejection::PathRejection, FromRequestParts, Path},
+    extract::{rejection::PathRejection, FromRequestParts, Path},
     RequestPartsExt,
 };
 use serde::de::DeserializeOwned;
@@ -31,9 +31,11 @@ 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)]
 impl<T, S> FromRequestParts<S> for OptionalPath<T>
 where
     T: DeserializeOwned + Send + 'static,
@@ -45,19 +47,15 @@ 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

@@ -1,5 +1,5 @@
 use axum::{
-    extract::FromRequestParts,
+    extract::{FromRequestParts, OptionalFromRequestParts},
     response::{IntoResponse, Response},
     Error,
 };
@@ -18,6 +18,19 @@ use std::fmt;
 /// with the `multiple` attribute. Those values can be collected into a `Vec` or other sequential
 /// container.
 ///
+/// # `Option<Query<T>>` behavior
+///
+/// If `Query<T>` itself is used as an extractor and there is no query string in
+/// the request URL, `T`'s `Deserialize` implementation is called on an empty
+/// string instead.
+///
+/// You can avoid this by using `Option<Query<T>>`, which gives you `None` in
+/// the case that there is no query string in the request URL.
+///
+/// Note that an empty query string is not the same as no query string, that is
+/// `https://example.org/` and `https://example.org/?` are not treated the same
+/// in this case.
+///
 /// # Example
 ///
 /// ```rust,no_run
@@ -96,6 +109,27 @@ where
     }
 }
 
+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`].
@@ -182,9 +216,11 @@ 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<Query<_>> instead"]
 #[derive(Debug, Clone, Copy, Default)]
 pub struct OptionalQuery<T>(pub Option<T>);
 
+#[allow(deprecated)]
 impl<T, S> FromRequestParts<S> for OptionalQuery<T>
 where
     T: DeserializeOwned,
@@ -204,6 +240,7 @@ where
     }
 }
 
+#[allow(deprecated)]
 impl<T> std::ops::Deref for OptionalQuery<T> {
     type Target = Option<T>;
 
@@ -213,6 +250,7 @@ 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 {
@@ -260,6 +298,7 @@ impl std::error::Error for OptionalQueryRejection {
 }
 
 #[cfg(test)]
+#[allow(deprecated)]
 mod tests {
     use super::*;
     use crate::test_helpers::*;

axum-extra/src/typed_header.rs

@@ -1,7 +1,7 @@
 //! Extractor and response for typed headers.
 
 use axum::{
-    extract::FromRequestParts,
+    extract::{FromRequestParts, OptionalFromRequestParts},
     response::{IntoResponse, IntoResponseParts, Response, ResponseParts},
 };
 use headers::{Header, HeaderMapExt};
@@ -78,6 +78,30 @@ where
     }
 }
 
+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/typed_path/pass/option_result.rs → axum-macros/tests/typed_path/pass/result_handler.rs

@@ -8,8 +8,6 @@ struct UsersShow {
     id: String,
 }
 
-async fn option_handler(_: Option<UsersShow>) {}
-
 async fn result_handler(_: Result<UsersShow, PathRejection>) {}
 
 #[derive(TypedPath, Deserialize)]
@@ -20,7 +18,6 @@ async fn result_handler_unit_struct(_: Result<UsersIndex, StatusCode>) {}
 
 fn main() {
     _ = axum::Router::<()>::new()
-        .typed_get(option_handler)
         .typed_post(result_handler)
         .typed_post(result_handler_unit_struct);
 }

axum/CHANGELOG.md

@@ -20,10 +20,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   This allows middleware to add bodies to requests without needing to manually set `content-length` ([#2897])
 - **breaking:** Remove `WebSocket::close`.
   Users should explicitly send close messages themselves. ([#2974])
+- **breaking:** `Option<Path<T>>` and `Option<Query<T>>` no longer swallow all error conditions,
+  instead rejecting the request in many cases; see their documentation for details ([#2475])
 - **added:** Extend `FailedToDeserializePathParams::kind` enum with (`ErrorKind::DeserializeError`)
   This new variant captures both `key`, `value`, and `message` from named path parameters parse errors,
   instead of only deserialization error message in `ErrorKind::Message`. ([#2720])
 
+[#2475]: https://github.com/tokio-rs/axum/pull/2475
 [#2897]: https://github.com/tokio-rs/axum/pull/2897
 [#2903]: https://github.com/tokio-rs/axum/pull/2903
 [#2894]: https://github.com/tokio-rs/axum/pull/2894

axum/Cargo.toml

@@ -116,6 +116,7 @@ features = [
 
 [dev-dependencies]
 anyhow = "1.0"
+axum-extra = { path = "../axum-extra", features = ["typed-header"] }
 axum-macros = { path = "../axum-macros", features = ["__private"] }
 hyper = { version = "1.1.0", features = ["client"] }
 quickcheck = "1.0"