feat(server + client): streaming mutations and queries over HTTP (#5700)

src/client/index.ts

@@ -1,7 +1,7 @@
 /**
  * This is the client-side code that uses the inferred types from the server
  */
-import { createTRPCClient, httpBatchLink } from '@trpc/client';
+import { createTRPCClient, unstable_httpBatchStreamLink } from '@trpc/client';
 /**
  * We only import the `AppRouter` type from the server - this is not available at runtime
  */
@@ -10,7 +10,7 @@ import type { AppRouter } from '../server/index.js';
 // Initialize the tRPC client
 const trpc = createTRPCClient<AppRouter>({
   links: [
-    httpBatchLink({
+    unstable_httpBatchStreamLink({
       url: 'http://localhost:3000',
     }),
   ],
@@ -34,3 +34,9 @@ console.log('Created user:', createdUser);
 const user = await trpc.user.byId.query('1');
 //    ^?
 console.log('User 1:', user);
+
+const iterable = await trpc.examples.iterable.query();
+
+for await (const i of iterable) {
+  console.log('Iterable:', i);
+}

src/server/index.ts

@@ -32,6 +32,14 @@ const appRouter = router({
         return user;
       }),
   },
+  examples: {
+    iterable: publicProcedure.query(async function* () {
+      for (let i = 0; i < 3; i++) {
+        await new Promise((resolve) => setTimeout(resolve, 500));
+        yield i;
+      }
+    }),
+  },
 });
 
 // Export type router type signature, this is used by the client.

src/server/trpc.ts

@@ -4,7 +4,11 @@ import { initTRPC } from '@trpc/server';
  * Initialization of tRPC backend
  * Should be done only once per backend!
  */
-const t = initTRPC.create();
+const t = initTRPC.create({
+  experimental: {
+    iterablesAndDeferreds: true,
+  },
+});
 
 /**
  * Export reusable router and procedure helpers