api: Introduce OutgoingResponse trait

ruma-api-macros/src/api/response.rs

@@ -116,7 +116,7 @@ impl Response {
                         if segments.last().unwrap().ident == "Option" =>
                     {
                         quote! {
-                            if let Some(header) = response.#field_name {
+                            if let Some(header) = self.#field_name {
                                 headers
                                     .insert(
                                         #http::header::#header_name,
@@ -129,7 +129,7 @@ impl Response {
                         headers
                             .insert(
                                 #http::header::#header_name,
-                                response.#field_name.parse()?,
+                                self.#field_name.parse()?,
                             );
                     },
                 };
@@ -152,13 +152,13 @@ impl Response {
         if let Some(field) = self.newtype_raw_body_field() {
             let field_name = field.ident.as_ref().expect("expected field to have an identifier");
             let span = field.span();
-            return quote_spanned!(span=> response.#field_name);
+            return quote_spanned!(span=> self.#field_name);
         }
 
         let body = if let Some(field) = self.newtype_body_field() {
             let field_name = field.ident.as_ref().expect("expected field to have an identifier");
             let span = field.span();
-            quote_spanned!(span=> response.#field_name)
+            quote_spanned!(span=> self.#field_name)
         } else {
             let fields = self.fields.iter().filter_map(|response_field| {
                 if let ResponseField::Body(ref field) = *response_field {
@@ -170,7 +170,7 @@ impl Response {
 
                     Some(quote_spanned! {span=>
                         #( #cfg_attrs )*
-                        #field_name: response.#field_name
+                        #field_name: self.#field_name
                     })
                 } else {
                     None
@@ -285,10 +285,13 @@ impl Response {
 
             #[automatically_derived]
             #[cfg(feature = "server")]
-            impl ::std::convert::TryFrom<Response> for #http::Response<Vec<u8>> {
-                type Error = #ruma_api::error::IntoHttpError;
-
-                fn try_from(response: Response) -> ::std::result::Result<Self, Self::Error> {
+            impl #ruma_api::OutgoingResponse for Response {
+                fn try_into_http_response(
+                    self,
+                ) -> ::std::result::Result<
+                    #http::Response<::std::vec::Vec<u8>>,
+                    #ruma_api::error::IntoHttpError,
+                > {
                     let mut resp_builder = #http::Response::builder()
                         .header(#http::header::CONTENT_TYPE, "application/json");
 
@@ -300,8 +303,7 @@ impl Response {
                     // This cannot fail because we parse each header value
                     // checking for errors as each value is inserted and
                     // we only allow keys from the `http::header` module.
-                    let response = resp_builder.body(#body).unwrap();
-                    Ok(response)
+                    Ok(resp_builder.body(#body).unwrap())
                 }
             }
 

ruma-api/src/lib.rs

@@ -20,7 +20,7 @@
 #[cfg(not(all(feature = "client", feature = "server")))]
 compile_error!("ruma_api's Cargo features only exist as a workaround are not meant to be disabled");
 
-use std::{convert::TryInto, error::Error as StdError};
+use std::{convert::TryInto as _, error::Error as StdError};
 
 use bytes::Buf;
 use http::Method;
@@ -306,7 +306,7 @@ pub trait IncomingRequest: Sized {
     type EndpointError: EndpointError;
 
     /// Response type to return when the request is successful.
-    type OutgoingResponse: TryInto<http::Response<Vec<u8>>, Error = IntoHttpError>;
+    type OutgoingResponse: OutgoingResponse;
 
     /// Metadata about the endpoint.
     const METADATA: Metadata;
@@ -315,6 +315,15 @@ pub trait IncomingRequest: Sized {
     fn try_from_http_request(req: http::Request<Vec<u8>>) -> Result<Self, FromHttpRequestError>;
 }
 
+/// A request type for a Matrix API endpoint, used for sending responses.
+pub trait OutgoingResponse {
+    /// Tries to convert this response into an `http::Response`.
+    ///
+    /// This method should only fail when when invalid header values are specified. It may also
+    /// fail with a serialization error in case of bugs in Ruma though.
+    fn try_into_http_response(self) -> Result<http::Response<Vec<u8>>, IntoHttpError>;
+}
+
 /// Marker trait for requests that don't require authentication, for the client side.
 pub trait OutgoingNonAuthRequest: OutgoingRequest {}
 

ruma-api/tests/header_override.rs

@@ -1,7 +1,5 @@
-use std::convert::TryFrom;
-
 use http::header::{Entry, CONTENT_TYPE};
-use ruma_api::{ruma_api, OutgoingRequest as _};
+use ruma_api::{ruma_api, OutgoingRequest as _, OutgoingResponse as _};
 
 ruma_api! {
     metadata: {
@@ -30,7 +28,7 @@ ruma_api! {
 #[test]
 fn response_content_type_override() {
     let res = Response { stuff: "magic".into() };
-    let mut http_res = http::Response::<Vec<u8>>::try_from(res).unwrap();
+    let mut http_res = res.try_into_http_response().unwrap();
 
     // Test that we correctly replaced the default content type,
     // not adding another content-type header.

ruma-api/tests/manual_endpoint_impl.rs

@@ -7,6 +7,7 @@ use http::{header::CONTENT_TYPE, method::Method};
 use ruma_api::{
     error::{FromHttpRequestError, FromHttpResponseError, IntoHttpError, ServerError, Void},
     AuthScheme, EndpointError, IncomingRequest, IncomingResponse, Metadata, OutgoingRequest,
+    OutgoingResponse,
 };
 use ruma_identifiers::{RoomAliasId, RoomId};
 use ruma_serde::Outgoing;
@@ -113,10 +114,8 @@ impl IncomingResponse for Response {
     }
 }
 
-impl TryFrom<Response> for http::Response<Vec<u8>> {
-    type Error = IntoHttpError;
-
-    fn try_from(_: Response) -> Result<http::Response<Vec<u8>>, Self::Error> {
+impl OutgoingResponse for Response {
+    fn try_into_http_response(self) -> Result<http::Response<Vec<u8>>, IntoHttpError> {
         let response = http::Response::builder()
             .header(CONTENT_TYPE, "application/json")
             .body(b"{}".to_vec())

ruma-api/tests/no_fields.rs

@@ -1,6 +1,4 @@
-use std::convert::TryFrom;
-
-use ruma_api::{ruma_api, OutgoingRequest as _};
+use ruma_api::{ruma_api, OutgoingRequest as _, OutgoingResponse as _};
 
 ruma_api! {
     metadata: {
@@ -27,7 +25,7 @@ fn empty_request_http_repr() {
 #[test]
 fn empty_response_http_repr() {
     let res = Response {};
-    let http_res = http::Response::<Vec<u8>>::try_from(res).unwrap();
+    let http_res = res.try_into_http_response().unwrap();
 
     assert_eq!(http_res.body(), b"{}");
 }

ruma-api/tests/ui/05-request-only.rs

@@ -1,9 +1,7 @@
-use std::convert::TryFrom;
-
 use bytes::Buf;
 use ruma_api::{
     error::{FromHttpResponseError, IntoHttpError, Void},
-    ruma_api, IncomingResponse,
+    ruma_api, IncomingResponse, OutgoingResponse,
 };
 use ruma_serde::Outgoing;
 
@@ -37,10 +35,8 @@ impl IncomingResponse for Response {
     }
 }
 
-impl TryFrom<Response> for http::Response<Vec<u8>> {
-    type Error = IntoHttpError;
-
-    fn try_from(_: Response) -> Result<Self, Self::Error> {
+impl OutgoingResponse for Response {
+    fn try_into_http_response(self) -> Result<http::Response<Vec<u8>>, IntoHttpError> {
         todo!()
     }
 }