1 files changed, 30 insertions, 17 deletions

diff --git a/src/header.rs b/src/header.rs
index 61cc561..683c1f9 100644
--- a/src/header.rs
+++ b/src/header.rs
@@ -1,16 +1,22 @@
+use std::ops::Deref;
+
 use axum::{
     extract::FromRequestParts,
     http::{request::Parts, HeaderName, HeaderValue},
 };
 use axum_extra::typed_header::TypedHeader;
+use serde::{de::DeserializeOwned, Serialize};
 
 /// A typed header. When used as a bare extractor, reads from the
 /// `Last-Event-Id` HTTP header.
-pub struct LastEventId(pub String);
+pub struct LastEventId<T>(pub T);
 
 static LAST_EVENT_ID: HeaderName = HeaderName::from_static("last-event-id");
 
-impl headers::Header for LastEventId {
+impl<T> headers::Header for LastEventId<T>
+where
+    T: Serialize + DeserializeOwned,
+{
     fn name() -> &'static HeaderName {
         &LAST_EVENT_ID
     }
@@ -20,11 +26,9 @@ impl headers::Header for LastEventId {
         I: Iterator<Item = &'i HeaderValue>,
     {
         let value = values.next().ok_or_else(headers::Error::invalid)?;
-        if let Ok(value) = value.to_str() {
-            Ok(Self(value.into()))
-        } else {
-            Err(headers::Error::invalid())
-        }
+        let value = value.to_str().map_err(|_| headers::Error::invalid())?;
+        let value = serde_json::from_str(value).map_err(|_| headers::Error::invalid())?;
+        Ok(Self(value))
     }
 
     fn encode<E>(&self, values: &mut E)
@@ -33,16 +37,18 @@ impl headers::Header for LastEventId {
     {
         let Self(value) = self;
         // Must panic or suppress; the trait provides no other options.
-        let value = HeaderValue::from_str(value).expect("LastEventId is a valid header value");
+        let value = serde_json::to_string(value).expect("value can be encoded as JSON");
+        let value = HeaderValue::from_str(&value).expect("LastEventId is a valid header value");
 
         values.extend(std::iter::once(value));
     }
 }
 
 #[async_trait::async_trait]
-impl<S> FromRequestParts<S> for LastEventId
+impl<S, T> FromRequestParts<S> for LastEventId<T>
 where
     S: Send + Sync,
+    T: Serialize + DeserializeOwned,
 {
     type Rejection = <TypedHeader<Self> as FromRequestParts<S>>::Rejection;
 
@@ -57,17 +63,24 @@ where
     }
 }
 
-impl From<String> for LastEventId {
-    fn from(header: String) -> Self {
-        Self(header)
-    }
-}
-
-impl std::ops::Deref for LastEventId {
-    type Target = str;
+impl<T> Deref for LastEventId<T> {
+    type Target = T;
 
     fn deref(&self) -> &Self::Target {
         let Self(header) = self;
         header
     }
 }
+
+impl<T> From<T> for LastEventId<T> {
+    fn from(value: T) -> Self {
+        Self(value)
+    }
+}
+
+impl<T> LastEventId<T> {
+    pub fn into_inner(self) -> T {
+        let Self(value) = self;
+        value
+    }
+}