Next.js

In this tutorial, we’ll create a Next.js app that calls a long-running background job using QStash.

Prerequisites

• Create an Upstash account and get your QStash token
• Node.js installed

1. Create Next.js app and install QStash

   npx create-next-app@latest --ts --eslint --tailwind --src-dir --app --import-alias='@/*' qstash-bg-job 
   

   cd qstash-bg-job
   

   npm install @upstash/qstash
   

   npm run dev
   

2. Create UI

   After removing the default content in src/app/page.tsx, let’s create a simple UI to trigger the background job using a button.

   src/app/page.tsx

   "use client"
   
   export default function Home() {
     return (
       <main className="flex h-lvh items-center justify-center">
         <button onClick={handleClick} className="btn btn-primary w-1/2 h-56 bg-green-500 text-xl sm:text-3xl rounded-lg hover:bg-green-600">
           Start Background Job
         </button>
       </main>
     );
   }
   

   Beautiful
3. Start Background Job

   We can use QStash to start a background job by calling the publishJSON method. In this example, we’re using Next.js server actions, but you can also use route handlers.

   Since we don’t have our public API endpoint yet, we can use Request Catcher to test the background job. This will eventually be replaced with our own API endpoint.

   src/app/actions.ts

   "use server"
   import { Client } from "@upstash/qstash";
   
   const qstashClient = new Client({
     // Add your token to a .env file
     token: process.env.QSTASH_TOKEN!,
   });
   
   export async function startBackgroundJob() {
     await qstashClient.publishJSON({
       "url": "https://firstqstashmessage.requestcatcher.com/test",
       body: {
         "hello": "world"
       }
     });
   }
   

   Now let’s invoke the startBackgroundJob function when the button is clicked.

   src/app/page.tsx

   "use client"
   import { startBackgroundJob } from "@/app/actions";
   
   export default function Home() {
     async function handleClick() {
       await startBackgroundJob();
     }
   
     return (
       <main className="flex h-lvh items-center justify-center">
         <button onClick={handleClick} className="btn btn-primary w-1/2 h-56 bg-green-500 text-xl sm:text-3xl rounded-lg hover:bg-green-600">
           Start Background Job
         </button>
       </main>
     );
   }
   

   To test the background job, click the button and check the Request Catcher for the incoming request.

   Verification screenshots

   You can also head over to Upstash Console and go to the Logs tab where you can see your message activities.
4. Create your own endpoint

   Now that we know QStash is working, let’s create our own endpoint to handle a background job. This is the endpoint that will be invoked by QStash.

   This job will be responsible for sending 10 requests, each with a 500ms delay. Since we’re deploying to Vercel, we have to be cautious of the time limit for serverless functions.

   src/app/api/long-task/route.ts

   export async function POST(request: Request) {
     const data = await request.json()
   
     for (let i = 0; i < 10; i++) {
       await fetch('https://firstqstashmessage.requestcatcher.com/test', {
         method: 'POST',
         body: JSON.stringify(data),
         headers: { 'Content-Type': 'application/json' }
       })
       await new Promise(resolve => setTimeout(resolve, 500))
     }
   
   
     return Response.json({ success: true })
   }
   

   Now let’s update our startBackgroundJob function to use our new endpoint.

   There’s 1 problem: our endpoint is not public. We need to make it public so that QStash can call it. We have 2 options:

   1. Deploy our application to a platform like Vercel and use the public URL.
   2. Create a local tunnel to test the endpoint locally.

   For the purpose, of this tutorial, I’ll deploy the application to Vercel, but feel free to use a local tunnel if you prefer.

   Deploying to Vercel

   There are many ways to deploy to Vercel, but I’m going to use the Vercel CLI.

   npm install -g vercel
   

   vercel
   

   Once deployed, you can find the public URL in the Vercel dashboard.

   Now that we have a public URL, we can update the URL.

   src/app/actions.ts

   "use server"
   import { Client } from "@upstash/qstash";
   
   const qstashClient = new Client({
     token: process.env.QSTASH_TOKEN!,
   });
   
   export async function startBackgroundJob() {
     await qstashClient.publishJSON({
       // Replace with your public URL
       "url": "https://qstash-bg-job.vercel.app/api/long-task",
       body: {
         "hello": "world"
       }
     })
   }
   

   And voila! You’ve created a Next.js app that calls a long-running background job using QStash.

5. Error catching and security

   QStash is a great way to handle background jobs, but it’s important to remember that it’s a public API. This means that anyone can call your endpoint. Make sure to add security measures to your endpoint to ensure that QStash is the sender of the request.

   Luckily, our SDK provides a way to verify the sender of the request. Make sure to get your signing keys from the QStash console and add them to your environment variables. The verifySignatureAppRouter will try to load QSTASH_CURRENT_SIGNING_KEY and QSTASH_NEXT_SIGNING_KEY from the environment. If one of them is missing, an error is thrown.

   src/app/api/long-task/route.ts

   import { verifySignatureAppRouter } from "@upstash/qstash/dist/nextjs";
   
   async function handler(request: Request) {
     const data = await request.json();
   
     for (let i = 0; i < 10; i++) {
       await fetch('https://firstqstashmessage.requestcatcher.com/test', {
         method: 'POST',
         body: JSON.stringify(data),
         headers: { 'Content-Type': 'application/json' }
       });
       await new Promise(resolve => setTimeout(resolve, 500));
     }
   
   
     return Response.json({ success: true });
   }
   
   export const POST = verifySignatureAppRouter(handler);
   

   Let’s also add error catching to our action and a loading state to our UI.

   src/app/actions.ts

   "use server"
   import { Client } from "@upstash/qstash";
   
   const qstashClient = new Client({
     token: process.env.QSTASH_TOKEN!,
   });
   
   export async function startBackgroundJob() {
     try {
       const response = await qstashClient.publishJSON({
         "url": "https://qstash-bg-job.vercel.app/api/long-task",
         body: {
           "hello": "world"
         }
       });
       return response.messageId;
     } catch (error) {
       console.error(error);
       return null;
     }
   }
   

Result

We have now created a Next.js app that calls a long-running background job using QStash! Here’s the app in action:

We can also view the logs on Vercel and QStash

Logs

Vercel

QStash

And the code for the 3 files we created:

src/app/page.tsx

"use client"
import { startBackgroundJob } from "@/app/actions";
import { useState } from "react";

export default function Home() {
  const [loading, setLoading] = useState(false);
  const [msg, setMsg] = useState("");

  async function handleClick() {
    setLoading(true);
    const messageId = await startBackgroundJob();
    if (messageId) {
      setMsg(`Started job with ID ${messageId}`);
    } else {
      setMsg("Failed to start background job");
    }
    setLoading(false);
  }

  return (
    <main className="flex flex-col h-lvh items-center justify-center">
      <button onClick={handleClick} disabled={loading} className="btn btn-primary w-1/2 h-56 bg-green-500 text-xl sm:text-3xl rounded-lg hover:bg-green-600 disabled:bg-gray-500">
        Start Background Job
      </button>

      {loading && <div className="text-2xl mt-8">Loading...</div>}
      {msg && <p className="text-center text-lg">{msg}</p>}
    </main>
  );
}

Now, go ahead and try it out for yourself! Try using some of the other features of QStash, like schedules, callbacks, and topics.

Assistant

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