JSON error (playing with serde API)

crates/librqbit/src/http_api_error.rs

@@ -1,7 +1,10 @@
+use std::ops::Deref;
+
 use axum::{
     http::StatusCode,
     response::{IntoResponse, Response},
 };
+use serde::{ser::SerializeMap, Serialize, Serializer};
 
 // Convenience error type.
 #[derive(Debug)]
@@ -38,6 +41,53 @@ enum ApiErrorKind {
     Other(anyhow::Error),
 }
 
+struct ErrWrap<'a, E: ?Sized>(&'a E);
+
+impl<'a, E> Serialize for ErrWrap<'a, E>
+where
+    E: std::error::Error + ?Sized,
+{
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let mut m = serializer.serialize_map(None)?;
+        m.serialize_entry("description", &format!("{}", self.0))?;
+        if let Some(source) = self.0.source() {
+            m.serialize_entry("source", &ErrWrap(source))?;
+        }
+        m.end()
+    }
+}
+
+impl Serialize for ApiErrorKind {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        match self {
+            ApiErrorKind::TorrentNotFound(id) => {
+                let mut m = serializer.serialize_map(None)?;
+                m.serialize_entry("error_kind", "torrent_not_found")?;
+                m.serialize_entry("id", id)?;
+                m.end()
+            }
+            ApiErrorKind::DhtDisabled => {
+                let mut m = serializer.serialize_map(None)?;
+                m.serialize_entry("error_kind", "dht_disabled")?;
+                m.end()
+            }
+            ApiErrorKind::Other(err) => {
+                let mut m = serializer.serialize_map(None)?;
+                m.serialize_entry("error_kind", "internal_error")?;
+                m.serialize_entry("human_readable", &format!("{err:#}"))?;
+                m.serialize_entry("error_chain", &ErrWrap(err.deref()))?;
+                m.end()
+            }
+        }
+    }
+}
+
 impl From<anyhow::Error> for ApiError {
     fn from(value: anyhow::Error) -> Self {
         Self {
@@ -68,7 +118,7 @@ impl std::fmt::Display for ApiError {
 
 impl IntoResponse for ApiError {
     fn into_response(self) -> Response {
-        let mut response = format!("{self}").into_response();
+        let mut response = axum::Json(&self.kind).into_response();
         *response.status_mut() = match self.status {
             Some(s) => s,
             None => StatusCode::INTERNAL_SERVER_ERROR,