From dc5c202c5f6ad8be0466cc2172d656e883fce648 Mon Sep 17 00:00:00 2001
From: Leon Lux <leonlux@icloud.com>
Date: Sun, 17 Nov 2024 22:12:45 +0100
Subject: [PATCH] Add shorthand way to return non-IntoResponse errors (#3010)

Co-authored-by: Jonas Platte <jplatte+git@posteo.de>
---
 axum-extra/Cargo.toml                     |  1 +
 axum-extra/src/response/error_response.rs | 51 +++++++++++++++++++++++
 axum-extra/src/response/mod.rs            |  6 +++
 3 files changed, 58 insertions(+)
 create mode 100644 axum-extra/src/response/error_response.rs

diff --git a/axum-extra/Cargo.toml b/axum-extra/Cargo.toml
index 10459f70..c357975a 100644
--- a/axum-extra/Cargo.toml
+++ b/axum-extra/Cargo.toml
@@ -16,6 +16,7 @@ default = ["tracing", "multipart"]
 
 async-read-body = ["dep:tokio-util", "tokio-util?/io", "dep:tokio"]
 attachment = ["dep:tracing"]
+error_response = ["dep:tracing", "tracing/std"]
 cookie = ["dep:cookie"]
 cookie-private = ["cookie", "cookie?/private"]
 cookie-signed = ["cookie", "cookie?/signed"]
diff --git a/axum-extra/src/response/error_response.rs b/axum-extra/src/response/error_response.rs
new file mode 100644
index 00000000..07069505
--- /dev/null
+++ b/axum-extra/src/response/error_response.rs
@@ -0,0 +1,51 @@
+use axum_core::response::{IntoResponse, Response};
+use http::StatusCode;
+use std::error::Error;
+use tracing::error;
+
+/// Convenience response to create an error response from a non-[`IntoResponse`] error
+///
+/// This provides a method to quickly respond with an error that does not implement
+/// the `IntoResponse` trait itself. This type should only be used for debugging purposes or internal
+/// facing applications, as it includes the full error chain with descriptions,
+/// thus leaking information that could possibly be sensitive.
+///
+/// ```rust
+/// use axum_extra::response::InternalServerError;
+/// use axum_core::response::IntoResponse;
+/// # use std::io::{Error, ErrorKind};
+/// # fn try_thing() -> Result<(), Error> {
+/// #   Err(Error::new(ErrorKind::Other, "error"))
+/// # }
+///
+/// async fn maybe_error() -> Result<String, InternalServerError<Error>> {
+///     try_thing().map_err(InternalServerError)?;
+///     // do something on success
+///     # Ok(String::from("ok"))
+/// }
+/// ```
+#[derive(Debug)]
+pub struct InternalServerError<T>(pub T);
+
+impl<T: Error + 'static> IntoResponse for InternalServerError<T> {
+    fn into_response(self) -> Response {
+        error!(error = &self.0 as &dyn Error);
+        (
+            StatusCode::INTERNAL_SERVER_ERROR,
+            "An error occurred while processing your request.",
+        )
+            .into_response()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::io::{Error, ErrorKind};
+
+    #[test]
+    fn internal_server_error() {
+        let response = InternalServerError(Error::new(ErrorKind::Other, "Test")).into_response();
+        assert_eq!(response.status(), StatusCode::INTERNAL_SERVER_ERROR);
+    }
+}
diff --git a/axum-extra/src/response/mod.rs b/axum-extra/src/response/mod.rs
index 12e104d8..bac7d040 100644
--- a/axum-extra/src/response/mod.rs
+++ b/axum-extra/src/response/mod.rs
@@ -9,6 +9,12 @@ mod attachment;
 #[cfg(feature = "multipart")]
 pub mod multiple;
 
+#[cfg(feature = "error_response")]
+mod error_response;
+
+#[cfg(feature = "error_response")]
+pub use error_response::InternalServerError;
+
 #[cfg(feature = "erased-json")]
 pub use erased_json::ErasedJson;