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use axum::{
extract::{Extension, FromRequestParts, Request},
http::{request::Parts, StatusCode},
middleware::Next,
response::Response,
};
use chrono::{DateTime, 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<Utc>);
impl RequestedAt {
fn now() -> Self {
Self(Utc::now())
}
pub fn timestamp(&self) -> DateTime<Utc> {
self.0
}
}
#[async_trait::async_trait]
impl<S> FromRequestParts<S> for RequestedAt
where
S: Send + Sync,
{
type Rejection = <Extension<RequestedAt> 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::<RequestedAt>::from_request_parts(parts, state).await?;
Ok(requested_at)
}
}
/// 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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