Add a separate trait for optional extractors (#2475)

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::*;