Changes to the incremental responses

.changeset/witty-pens-nail.md

@@ -0,0 +1,5 @@
+---
+'@as-integrations/next': minor
+---
+
+Add support for incremental delivery

README.md

@@ -7,7 +7,7 @@ An Apollo Server integration for use with Next.js.
 First create a Next.js API route by creating a file at for example `pages/api/graphql.js`.  
 This API route will be accessible at `/api/graphql`.
 
-Next create an Apollo Server instance and pass it to `startServerAndCreateNextHandler`:
+Next, create an Apollo Server instance and pass it to `startServerAndCreateNextHandler`:
 
 ```js
 import { ApolloServer } from '@apollo/server';
@@ -46,15 +46,11 @@ The Next.js `req` and `res` objects are passed along to the context function.
 
 ## App Router (Route Handlers)
 
-This integration has experimental support for [Next.js' App Router](https://nextjs.org/docs/app/building-your-application/routing/router-handlers), which is now the stable and default project structure for Next.js.
+First create a Next.js Route Handler by creating a file at for example `app/api/graphql/route.js`.  
+This Route Handler will be accessible at `/api/graphql`.
 
-Make sure you're on recent version of Next.js (13.4+), then create a new Route
-Handler file, for example at `app/api/graphql/route.js`.
-
-This file's route handlers will be accessible at URI path `/api/graphql`.
-
-Next create an Apollo Server instance, pass it to `startServerAndCreateNextHandler` and
-finally pass the handler to both a GET and a POST route handler:
+Next, create an Apollo Server instance, pass it to `startServerAndCreateNextHandler` and  
+finally export the handler both as GET and POST:
 
 ```js
 import { startServerAndCreateNextHandler } from '@as-integrations/next';
@@ -83,7 +79,7 @@ const handler = startServerAndCreateNextHandler(server);
 export { handler as GET, handler as POST };
 ```
 
-## Typescript
+## TypeScript
 
 When using this integration with Route Handlers you will have to specify the type of the incoming request object (`Response` or `NextResponse`) for the context function to receive the correct type signature:
 

src/__tests__/integration.test.ts

@@ -56,7 +56,6 @@ describe('nextHandler', () => {
       };
     },
     {
-      noIncrementalDelivery: true,
       serverIsStartedInBackground: true,
     },
   );

src/startServerAndCreateNextHandler.ts

@@ -4,6 +4,7 @@ import { isNextApiRequest } from './lib/isNextApiRequest';
 import { ApolloServer, BaseContext, ContextFunction } from '@apollo/server';
 import { NextApiRequest, NextApiResponse } from 'next';
 import { NextRequest } from 'next/server';
+import { Readable } from 'stream';
 import { parse } from 'url';
 
 type HandlerRequest = NextApiRequest | NextRequest | Request;
@@ -49,34 +50,38 @@ function startServerAndCreateNextHandler<
 
       if (httpGraphQLResponse.body.kind === 'complete') {
         res.send(httpGraphQLResponse.body.string);
+        res.end();
       } else {
-        for await (const chunk of httpGraphQLResponse.body.asyncIterator) {
-          res.write(chunk);
-        }
+        res.send(Readable.from(httpGraphQLResponse.body.asyncIterator));
       }
 
-      res.end();
       return;
     }
 
-    const body = [];
-
-    if (httpGraphQLResponse.body.kind === 'complete') {
-      body.push(httpGraphQLResponse.body.string);
-    } else {
-      for await (const chunk of httpGraphQLResponse.body.asyncIterator) {
-        body.push(chunk);
-      }
-    }
-
     const headers: Record<string, string> = {};
-
     for (const [key, value] of httpGraphQLResponse.headers) {
       headers[key] = value;
     }
 
     // eslint-disable-next-line consistent-return
-    return new Response(body.join(''), { headers, status: httpGraphQLResponse.status || 200 });
+    return new Response(
+      httpGraphQLResponse.body.kind === 'complete'
+        ? httpGraphQLResponse.body.string
+        : new ReadableStream({
+            async pull(controller) {
+              if (httpGraphQLResponse.body.kind === 'chunked') {
+                const { value, done } = await httpGraphQLResponse.body.asyncIterator.next();
+
+                if (done) {
+                  controller.close();
+                } else {
+                  controller.enqueue(value);
+                }
+              }
+            },
+          }),
+      { headers, status: httpGraphQLResponse.status || 200 },
+    );
   }
 
   return handler;