Extend custom rejection examples (#1276)

* examples: Created new `error-handling` example * examples(error-handling): Add error codes and responses * examples(error-handling): `custom_extractor` * examples(error-handling): `derive_from_request` * examples(error-handling): Using POST instead of GET * examples(error-handling): Using `thiserror` for `derive_from_request` * examples(error-handling): Using `snake-case` for routes * revert(error-handling): Use `From` impl instead of `thiserror` refs: 3533d96215 * examples(error-handling): Removed chrono * examples: merged `error-handling` and `customize-extractor-error` * examples(customize-extractor-error): Improved error codes * examples(customize-extractor-error): rustfmt * examples(customize-extractor-error): Removed `matched-path` feature Co-authored-by: David Pedersen <[email protected]> * examples(customize-extractor-error): added `publish=false` to `Cargo.toml` Co-authored-by: David Pedersen <[email protected]> * examples(customize-extractor-error): Fix env filter * examples(customize-extractor-error): Added README * examples(customize-extractor-error): Added `with_rejection` comments * examples(customize-extractor-error): Added `custom_extractor` comments * examples(customize-extractor-error):Typo on `with_rejection` * examples(customize-extractor-error): Added `boilerplate` con to `custom_extractor` * examples(customize-extractor-error): Added `derive_from_request` comments * examples(customize-extractor-error): typo impossible * examples(customize-extractor-error): typos * examples(customize-extractor-error): replaced `extensions` with `extract` * examples(customize-extractor-error): typo `from` Co-authored-by: David Pedersen <[email protected]> Co-authored-by: David Pedersen <[email protected]>
2026-08-26 00:00:23 +02:00 · 2022-08-19 13:11:03 +00:00
parent 18dd830b84
commit 789f51ba1a
6 changed files with 219 additions and 74 deletions
@@ -0,0 +1,69 @@
+//! Manual implementation of `FromRequest` that wraps another extractor
+//!
+//! + Powerful API: Implementing `FromRequest` grants access to `RequestParts`
+//!   and `async/await`. This means that you can create more powerful rejections
+//! - Boilerplate: Requires creating a new extractor for every custom rejection
+//! - Complexity: Manually implementing `FromRequest` results on more complex code
+use axum::extract::MatchedPath;
+use axum::{
+    async_trait,
+    extract::{rejection::JsonRejection, FromRequest, RequestParts},
+    http::StatusCode,
+    response::IntoResponse,
+    BoxError,
+};
+use serde::de::DeserializeOwned;
+use serde_json::{json, Value};
+
+pub async fn handler(Json(value): Json<Value>) -> impl IntoResponse {
+    Json(dbg!(value));
+}
+
+// We define our own `Json` extractor that customizes the error from `axum::Json`
+pub struct Json<T>(T);
+
+#[async_trait]
+impl<S, B, T> FromRequest<S, B> for Json<T>
+where
+    S: Send + Sync,
+    // these trait bounds are copied from `impl FromRequest for axum::Json`
+    // `T: Send` is required to send this future across an await
+    T: DeserializeOwned + Send,
+    B: axum::body::HttpBody + Send,
+    B::Data: Send,
+    B::Error: Into<BoxError>,
+{
+    type Rejection = (StatusCode, axum::Json<Value>);
+
+    async fn from_request(req: &mut RequestParts<S, B>) -> Result<Self, Self::Rejection> {
+        match axum::Json::<T>::from_request(req).await {
+            Ok(value) => Ok(Self(value.0)),
+            // convert the error from `axum::Json` into whatever we want
+            Err(rejection) => {
+                let path = req
+                    .extract::<MatchedPath>()
+                    .await
+                    .map(|x| x.as_str().to_owned())
+                    .ok();
+
+                // We can use other extractors to provide better rejection
+                // messages. For example, here we are using
+                // `axum::extract::MatchedPath` to provide a better error
+                // message
+                let payload = json!({
+                    "message": rejection.to_string(),
+                    "origin": "custom_extractor",
+                    "path": path,
+                });
+
+                let code = match rejection {
+                    JsonRejection::JsonDataError(_) => StatusCode::UNPROCESSABLE_ENTITY,
+                    JsonRejection::JsonSyntaxError(_) => StatusCode::BAD_REQUEST,
+                    JsonRejection::MissingJsonContentType(_) => StatusCode::UNSUPPORTED_MEDIA_TYPE,
+                    _ => StatusCode::INTERNAL_SERVER_ERROR,
+                };
+                Err((code, axum::Json(payload)))
+            }
+        }
+    }
+}