api: add xrpc query extractor

Lewis: May this revision serve well! <lu5a@proton.me>

crates/tranquil-pds/src/api/mod.rs

@@ -2,6 +2,7 @@ pub mod error;
 pub mod invite;
 pub mod proxy;
 pub mod proxy_client;
+pub mod query;
 pub mod responses;
 pub mod validation;
 

crates/tranquil-pds/src/api/query.rs

@@ -0,0 +1,18 @@
+use axum::extract::FromRequestParts;
+use axum::http::request::Parts;
+use serde::de::DeserializeOwned;
+
+use super::error::ApiError;
+
+pub struct XrpcQuery<T>(pub T);
+
+impl<T: DeserializeOwned, S: Send + Sync> FromRequestParts<S> for XrpcQuery<T> {
+    type Rejection = ApiError;
+
+    async fn from_request_parts(parts: &mut Parts, _state: &S) -> Result<Self, Self::Rejection> {
+        let raw = parts.uri.query().unwrap_or_default();
+        serde_urlencoded::from_str(raw)
+            .map(Self)
+            .map_err(|e| ApiError::InvalidRequest(e.to_string()))
+    }
+}