From 56e472169161d286ac37bc91722c6d36a382d553 Mon Sep 17 00:00:00 2001
From: Markus Blomqvist <blomqvist_markus@hotmail.com>
Date: Wed, 27 Mar 2024 00:59:32 +0200
Subject: [PATCH] Improve RPC route response serialization

This change serializes Blob data for API routes
and creates a JSON object from form responses,
although these are rare cases.
---
 .../src/pages/api/v1/rpc/[operationId].ts     |  8 +++++
 .../src/app-router/rpc-route.ts               | 20 ++++++------
 .../src/pages-router/rpc-api-route.ts         | 32 +++++++++++++++++--
 .../next-rest-framework/src/shared/utils.ts   | 14 ++++++++
 4 files changed, 60 insertions(+), 14 deletions(-)

diff --git a/apps/example/src/pages/api/v1/rpc/[operationId].ts b/apps/example/src/pages/api/v1/rpc/[operationId].ts
index 43078ae..006df1d 100644
--- a/apps/example/src/pages/api/v1/rpc/[operationId].ts
+++ b/apps/example/src/pages/api/v1/rpc/[operationId].ts
@@ -8,6 +8,14 @@ import {
 } from '@/actions';
 import { rpcApiRoute } from 'next-rest-framework';
 
+// Body parser must be disabled when parsing multipart/form-data requests with pages router.
+// A recommended way is to create a separate RPC API route for multipart/form-data requests.
+// export const config = {
+//   api: {
+//     bodyParser: false
+//   }
+// };
+
 const handler = rpcApiRoute({
   getTodos,
   getTodoById,
diff --git a/packages/next-rest-framework/src/app-router/rpc-route.ts b/packages/next-rest-framework/src/app-router/rpc-route.ts
index 92ab62d..1bdf871 100644
--- a/packages/next-rest-framework/src/app-router/rpc-route.ts
+++ b/packages/next-rest-framework/src/app-router/rpc-route.ts
@@ -7,7 +7,8 @@ import {
 import {
   validateSchema,
   logNextRestFrameworkError,
-  type RpcOperationDefinition
+  type RpcOperationDefinition,
+  parseRpcOperationResponseJson
 } from '../shared';
 import {
   type FormDataContentType,
@@ -194,21 +195,18 @@ export const rpcRoute = <
         );
       }
 
-      const parseRes = (res: unknown): BodyInit => {
-        if (
-          res instanceof ReadableStream ||
-          res instanceof ArrayBuffer ||
-          res instanceof Blob ||
-          res instanceof FormData ||
-          res instanceof URLSearchParams
-        ) {
+      const parseRes = async (res: unknown): Promise<BodyInit> => {
+        if (res instanceof ReadableStream || res instanceof Blob) {
           return res;
         }
 
-        return JSON.stringify(res);
+        const parsed = await parseRpcOperationResponseJson(res);
+        return JSON.stringify(parsed);
       };
 
-      return new NextResponse(parseRes(res), {
+      const json = await parseRes(res);
+
+      return new NextResponse(json, {
         status: 200,
         headers: {
           'Content-Type': 'application/json'
diff --git a/packages/next-rest-framework/src/pages-router/rpc-api-route.ts b/packages/next-rest-framework/src/pages-router/rpc-api-route.ts
index f64389f..b9e3bf0 100644
--- a/packages/next-rest-framework/src/pages-router/rpc-api-route.ts
+++ b/packages/next-rest-framework/src/pages-router/rpc-api-route.ts
@@ -7,7 +7,8 @@ import {
   validateSchema,
   logNextRestFrameworkError,
   type RpcOperationDefinition,
-  logPagesEdgeRuntimeErrorForRoute
+  logPagesEdgeRuntimeErrorForRoute,
+  parseRpcOperationResponseJson
 } from '../shared';
 import { type NextApiRequest, type NextApiResponse } from 'next/types';
 import {
@@ -117,7 +118,7 @@ export const rpcApiRoute = <
               // Parse multipart/form-data into a FormData object.
               try {
                 req.body = await parseMultiPartFormData(req);
-              } catch (e) {
+              } catch {
                 res.status(400).json({
                   message: `${DEFAULT_ERRORS.invalidRequestBody} Failed to parse form data.`
                 });
@@ -166,7 +167,32 @@ export const rpcApiRoute = <
         return;
       }
 
-      res.status(200).json(_res);
+      if (_res instanceof Blob) {
+        const reader = _res.stream().getReader();
+        res.setHeader('Content-Type', 'application/octet-stream');
+
+        res.setHeader(
+          'Content-Disposition',
+          `attachment; filename="${_res.name}"`
+        );
+
+        const pump = async () => {
+          await reader.read().then(async ({ done, value }) => {
+            if (done) {
+              res.end();
+              return;
+            }
+
+            res.write(value);
+            await pump();
+          });
+        };
+
+        await pump();
+      }
+
+      const json = await parseRpcOperationResponseJson(_res);
+      res.status(200).json(json);
     } catch (error) {
       logNextRestFrameworkError(error);
       res.status(400).json({ message: DEFAULT_ERRORS.unexpectedError });
diff --git a/packages/next-rest-framework/src/shared/utils.ts b/packages/next-rest-framework/src/shared/utils.ts
index b0fa235..ba24dbc 100644
--- a/packages/next-rest-framework/src/shared/utils.ts
+++ b/packages/next-rest-framework/src/shared/utils.ts
@@ -5,3 +5,17 @@ export const isValidMethod = (x: unknown): x is ValidMethod =>
 
 export const capitalizeFirstLetter = (str: string) =>
   str[0]?.toUpperCase() + str.slice(1);
+
+export const parseRpcOperationResponseJson = async (res: unknown) => {
+  if (res instanceof FormData || res instanceof URLSearchParams) {
+    const body: Record<string, FormDataEntryValue> = {};
+
+    for (const [key, value] of res.entries()) {
+      body[key] = value;
+    }
+
+    return body;
+  }
+
+  return res;
+};