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use axum::{
extract::{Extension, FromRequestParts, Request},
http::{request::Parts, StatusCode},
middleware::Next,
response::Response,
};
use chrono::Utc;
pub type DateTime = chrono::DateTime<chrono::Utc>;
// Extractor that provides the "current time" for a request. This time is
// calculated once per request, even if the extractor is used in multiple
// places. This requires the [middleware] function to be installed with
// [axum::middleware::from_fn] around the current route.
#[derive(Clone)]
pub struct RequestedAt(pub DateTime);
impl RequestedAt {
fn now() -> Self {
Self(Utc::now())
}
}
#[async_trait::async_trait]
impl<S> FromRequestParts<S> for RequestedAt
where
S: Send + Sync,
{
type Rejection = <Extension<Self> as FromRequestParts<S>>::Rejection;
async fn from_request_parts(parts: &mut Parts, state: &S) -> Result<Self, Self::Rejection> {
// This is purely for ergonomics: it allows `RequestedAt` to be extracted
// without having to wrap it in `Extension<>`. Callers _can_ still do that,
// but they aren't forced to.
let Extension(requested_at) = Extension::from_request_parts(parts, state).await?;
Ok(requested_at)
}
}
impl From<DateTime> for RequestedAt {
fn from(timestamp: DateTime) -> Self {
Self(timestamp)
}
}
impl std::ops::Deref for RequestedAt {
type Target = DateTime;
fn deref(&self) -> &Self::Target {
let Self(timestamp) = self;
timestamp
}
}
// Computes a canonical "requested at" time for each request it wraps. This
// time can be recovered using the [RequestedAt] extractor.
pub async fn middleware(mut req: Request, next: Next) -> Result<Response, StatusCode> {
let now = RequestedAt::now();
req.extensions_mut().insert(now);
Ok(next.run(req).await)
}
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