From 1fb61acff0f4264a1e996d143f17ae5e89849ec7 Mon Sep 17 00:00:00 2001
From: Tom Anderson <tom@ando.gq>
Date: Mon, 24 Jun 2024 11:46:29 +1000
Subject: [PATCH] return parameter deserialisation errors (close #69)

---
 .changes/return-param-errors.md        |  6 ++++++
 crates/qubit-macros/src/handler/mod.rs |  8 ++++++--
 src/builder/mod.rs                     |  3 +++
 src/builder/rpc_builder.rs             | 17 ++++++++++-------
 4 files changed, 25 insertions(+), 9 deletions(-)
 create mode 100644 .changes/return-param-errors.md

diff --git a/.changes/return-param-errors.md b/.changes/return-param-errors.md
new file mode 100644
index 0000000..3f67bd8
--- /dev/null
+++ b/.changes/return-param-errors.md
@@ -0,0 +1,6 @@
+---
+"qubit": patch:feat
+"qubit-macros": patch:feat
+---
+
+return parameter deserialising errors if they are encountered (close #69)
diff --git a/crates/qubit-macros/src/handler/mod.rs b/crates/qubit-macros/src/handler/mod.rs
index c5e8350..9a3e1a7 100644
--- a/crates/qubit-macros/src/handler/mod.rs
+++ b/crates/qubit-macros/src/handler/mod.rs
@@ -237,7 +237,10 @@ impl From<Handler> for TokenStream {
             // Generate the parameter parsing implementation
             let parse_params = (!inputs.is_empty()).then(|| {
                 quote! {
-                    let (#(#param_names,)*) = #params_ident.parse::<(#(#param_tys,)*)>().unwrap();
+                    let (#(#param_names,)*) = match #params_ident.parse::<(#(#param_tys,)*)>() {
+                        ::std::result::Result::Ok(params) => params,
+                        ::std::result::Result::Err(e) => return ::std::result::Result::Err(e),
+                    };
                 }
             });
 
@@ -251,7 +254,8 @@ impl From<Handler> for TokenStream {
             let register_inner = quote! {
                 #parse_params
 
-                #handler_call
+                let result = #handler_call;
+                ::std::result::Result::Ok::<_, ::qubit::ErrorObject>(result)
             };
 
             let register_method = match kind {
diff --git a/src/builder/mod.rs b/src/builder/mod.rs
index 81c8c8c..f807379 100644
--- a/src/builder/mod.rs
+++ b/src/builder/mod.rs
@@ -9,3 +9,6 @@ pub use handler::Handler;
 pub(crate) use handler::HandlerCallbacks;
 pub use rpc_builder::RpcBuilder;
 pub use ty::*;
+
+pub use jsonrpsee::types::ErrorObject;
+pub use jsonrpsee::IntoResponse;
diff --git a/src/builder/rpc_builder.rs b/src/builder/rpc_builder.rs
index 0eef4d4..55ed5d8 100644
--- a/src/builder/rpc_builder.rs
+++ b/src/builder/rpc_builder.rs
@@ -2,10 +2,10 @@ use std::ops::Deref;
 
 use futures::{Future, Stream, StreamExt};
 use jsonrpsee::{
-    types::{ErrorCode, Params, ResponsePayload},
-    RpcModule, SubscriptionCloseResponse, SubscriptionMessage,
+    types::{ErrorCode, ErrorObject, Params, ResponsePayload},
+    IntoResponse, RpcModule, SubscriptionCloseResponse, SubscriptionMessage,
 };
-use serde::Serialize;
+use serde::{de::Error, Serialize};
 use serde_json::json;
 
 use crate::{FromRequestExtensions, RequestKind, RpcError};
@@ -50,7 +50,7 @@ where
         T: Serialize + Clone + 'static,
         C: FromRequestExtensions<Ctx>,
         F: Fn(C, Params<'static>) -> Fut + Send + Sync + Clone + 'static,
-        Fut: Future<Output = T> + Send + 'static,
+        Fut: Future<Output = Result<T, ErrorObject<'static>>> + Send + 'static,
     {
         self.register_handler(name, handler, RequestKind::Query)
     }
@@ -61,7 +61,7 @@ where
         T: Serialize + Clone + 'static,
         C: FromRequestExtensions<Ctx>,
         F: Fn(C, Params<'static>) -> Fut + Send + Sync + Clone + 'static,
-        Fut: Future<Output = T> + Send + 'static,
+        Fut: Future<Output = Result<T, ErrorObject<'static>>> + Send + 'static,
     {
         self.register_handler(name, handler, RequestKind::Mutation)
     }
@@ -78,7 +78,7 @@ where
         T: Serialize + Clone + 'static,
         C: FromRequestExtensions<Ctx>,
         F: Fn(C, Params<'static>) -> Fut + Send + Sync + Clone + 'static,
-        Fut: Future<Output = T> + Send + 'static,
+        Fut: Future<Output = Result<T, jsonrpsee::types::ErrorObject<'static>>> + Send + 'static,
     {
         self.module
             .register_async_method(self.namespace_str(name), move |params, ctx, extensions| {
@@ -114,7 +114,10 @@ where
                         };
 
                     // Run the actual handler
-                    ResponsePayload::success(handler(ctx, params).await)
+                    match handler(ctx, params).await {
+                        Ok(result) => ResponsePayload::success(result),
+                        Err(e) => ResponsePayload::error(e),
+                    }
                 }
             })
             .unwrap();