How to send an early response and continue executing

[gregoryforel]

I am migrating a Google Cloud function to a Bun/Hono backend. My function currently allows me an early response and continue to proceed with the rest of the code.

Google Cloud function:

export const create_backup = v2.https.onRequest(
  async (request, response) => {    
      const { id: backupId } = ...

      // Early response to the client, as Sveltekit expects a response within 15 seconds. The backup will continue in the background, and we'll get notified
      response.status(HttpStatusCode.Accepted).json({
        status: 'In progress',
        data: { backupId },
      });

      // Continue to work
...
);

In Hono, I tried to simply use c.json without returning the statement, but it doesn't work:

 c.json(
      {
        status: 'In progress',
        data: { backupId },
      },
      HttpStatusCode.Accepted
    );

// above never sends anything back to the client
// ... continue

[nakasyou]

Hi @gregoryforel.

If you use Cloudflare Workers, can use c.executionCtx.waitUntil!

c.executionCtx.waitUntil((async () => {
  // This code is executed after the server has respond
})())
return c.json(
// ^ You have to add `return`
      {
        status: 'In progress',
        data: { backupId },
      },
      HttpStatusCode.Accepted
    );

If you don't, probably you can use like that:

;(async () => {
  // Describe the subsequent processing in this code
})()
return c.json(
// ^ You have to add `return`
      {
        status: 'In progress',
        data: { backupId },
      },
      HttpStatusCode.Accepted
    );

[gregoryforel]

Thank you! I'll try this as soon as I can!

[gregoryforel]

So, I'm not using Cloudflare Workers, and unfortunately, the other async solution does not work. I solved the issue using streamSSE but it feels very hacky for such a simple thing.

[mikkelsvartveit]

Did you find a good solution for this? This seems like a very common use case to me

[gregoryforel]

@mikkelsvartveit sorry, I hadn't seen your question.

return streamSSE(c, async (stream) => {
  // Send early response to the client (Sveltekit needs to receive a response within 15 seconds)
  await stream.write(
    JSON.stringify({
      status: HttpStatusCode.Accepted,
    })
  );

  // Close the stream to send the response immediately  
  await stream.close();

  // ... rest of the processing continues ...
});