Change HeaderMap extractor to clone the headers (#698)

* Change `HeaderMap` extractor to clone the headers

* fix docs

* changelog

* inline variable

* also add changelog item to axum

* don't list types from axum in axum-core's changelog

* document that `HeaderMap::from_request` clones the headers

* fix typo

* a few more typos

axum-core/src/extract/mod.rs

@@ -77,7 +77,7 @@ pub struct RequestParts<B> {
     method: Method,
     uri: Uri,
     version: Version,
-    headers: Option<HeaderMap>,
+    headers: HeaderMap,
     extensions: Option<Extensions>,
     body: Option<B>,
 }
@@ -107,7 +107,7 @@ impl<B> RequestParts<B> {
             method,
             uri,
             version,
-            headers: Some(headers),
+            headers,
             extensions: Some(extensions),
             body: Some(body),
         }
@@ -117,14 +117,11 @@ impl<B> RequestParts<B> {
     ///
     /// Fails if
     ///
-    /// - The full [`HeaderMap`] has been extracted, that is [`take_headers`]
-    /// have been called.
     /// - The full [`Extensions`] has been extracted, that is
     /// [`take_extensions`] have been called.
     /// - The request body has been extracted, that is [`take_body`] have been
     /// called.
     ///
-    /// [`take_headers`]: RequestParts::take_headers
     /// [`take_extensions`]: RequestParts::take_extensions
     /// [`take_body`]: RequestParts::take_body
     pub fn try_into_request(self) -> Result<Request<B>, RequestAlreadyExtracted> {
@@ -132,7 +129,7 @@ impl<B> RequestParts<B> {
             method,
             uri,
             version,
-            mut headers,
+            headers,
             mut extensions,
             mut body,
         } = self;
@@ -148,14 +145,7 @@ impl<B> RequestParts<B> {
         *req.method_mut() = method;
         *req.uri_mut() = uri;
         *req.version_mut() = version;
-
-        if let Some(headers) = headers.take() {
-            *req.headers_mut() = headers;
-        } else {
-            return Err(RequestAlreadyExtracted::HeadersAlreadyExtracted(
-                HeadersAlreadyExtracted,
-            ));
-        }
+        *req.headers_mut() = headers;
 
         if let Some(extensions) = extensions.take() {
             *req.extensions_mut() = extensions;
@@ -199,22 +189,13 @@ impl<B> RequestParts<B> {
     }
 
     /// Gets a reference to the request headers.
-    ///
-    /// Returns `None` if the headers has been taken by another extractor.
-    pub fn headers(&self) -> Option<&HeaderMap> {
-        self.headers.as_ref()
+    pub fn headers(&self) -> &HeaderMap {
+        &self.headers
     }
 
     /// Gets a mutable reference to the request headers.
-    ///
-    /// Returns `None` if the headers has been taken by another extractor.
-    pub fn headers_mut(&mut self) -> Option<&mut HeaderMap> {
-        self.headers.as_mut()
-    }
-
-    /// Takes the headers out of the request, leaving a `None` in its place.
-    pub fn take_headers(&mut self) -> Option<HeaderMap> {
-        self.headers.take()
+    pub fn headers_mut(&mut self) -> &mut HeaderMap {
+        &mut self.headers
     }
 
     /// Gets a reference to the request extensions.

axum-core/src/extract/rejection.rs

@@ -8,13 +8,6 @@ define_rejection! {
     pub struct BodyAlreadyExtracted;
 }
 
-define_rejection! {
-    #[status = INTERNAL_SERVER_ERROR]
-    #[body = "Headers taken by other extractor"]
-    /// Rejection used if the headers has been taken by another extractor.
-    pub struct HeadersAlreadyExtracted;
-}
-
 define_rejection! {
     #[status = INTERNAL_SERVER_ERROR]
     #[body = "Extensions taken by other extractor"]
@@ -47,7 +40,6 @@ composite_rejection! {
     /// [`Request<_>`]: http::Request
     pub enum RequestAlreadyExtracted {
         BodyAlreadyExtracted,
-        HeadersAlreadyExtracted,
         ExtensionsAlreadyExtracted,
     }
 }
@@ -79,7 +71,6 @@ composite_rejection! {
     ///
     /// Contains one variant for each way the [`http::request::Parts`] extractor can fail.
     pub enum RequestPartsAlreadyExtracted {
-        HeadersAlreadyExtracted,
         ExtensionsAlreadyExtracted,
     }
 }

axum-core/src/extract/request_parts.rs

@@ -19,7 +19,7 @@ where
                 method: req.method.clone(),
                 version: req.version,
                 uri: req.uri.clone(),
-                headers: None,
+                headers: HeaderMap::new(),
                 extensions: None,
                 body: None,
             },
@@ -65,15 +65,20 @@ where
     }
 }
 
+/// Clone the headers from the request.
+///
+/// Prefer using [`TypedHeader`] to extract only the headers you need.
+///
+/// [`TypedHeader`]: https://docs.rs/axum/latest/axum/extract/struct.TypedHeader.html
 #[async_trait]
 impl<B> FromRequest<B> for HeaderMap
 where
     B: Send,
 {
-    type Rejection = HeadersAlreadyExtracted;
+    type Rejection = Infallible;
 
     async fn from_request(req: &mut RequestParts<B>) -> Result<Self, Self::Rejection> {
-        req.take_headers().ok_or(HeadersAlreadyExtracted)
+        Ok(req.headers().clone())
     }
 }
 
@@ -143,7 +148,10 @@ where
         let method = unwrap_infallible(Method::from_request(req).await);
         let uri = unwrap_infallible(Uri::from_request(req).await);
         let version = unwrap_infallible(Version::from_request(req).await);
-        let headers = HeaderMap::from_request(req).await?;
+        let headers = match HeaderMap::from_request(req).await {
+            Ok(headers) => headers,
+            Err(err) => match err {},
+        };
         let extensions = Extensions::from_request(req).await?;
 
         let mut temp_request = Request::new(());