Use Queues from Durable Objects

Publish to a queue from within a Durable Object.

The following example shows you how to write a Worker script to publish to Cloudflare Queues from within a Durable Object.

Prerequisites:

A queue created via the Cloudflare dashboard or the wrangler CLI.
A configured producer binding in the Cloudflare dashboard or wrangler.toml file.
A Durable Object namespace binding.

Configure your wrangler.toml file as follows:

wrangler.tomlname = "my-worker"

[[queues.producers]]  queue = "my-queue"  binding = "YOUR_QUEUE"

[durable_objects]
bindings = [  { name = "YOUR_DO_CLASS", class_name = "YourDurableObject" }
]

The following Worker script:

Creates a Durable Object stub, or retrieves an existing one based on a userId.
Passes request data to the Durable Object.
Publishes to a queue from within the Durable Object.

The constructor() in the Durable Object makes your Environment available (in scope) on this.env to the fetch() handler in the Durable Object.

src/index.tsinterface Env {  YOUR_QUEUE: Queue;  YOUR_DO_CLASS: DurableObject;
}

export default {  async fetch(req: Request, env: Environment): Promise<Response> {    // Assume each Durable Object is mapped to a userId in a query parameter    // In a production application, this will be a userId defined by your application    // that you validate (and/or authenticate) first.    let url = new URL(req.url)    let userIdParam = url.searchParams.get("userId")
    if (userIdParam) {      // Create (or get) a Durable Object based on that userId.      let durableObjectId = env.YOUR_DO_CLASS.idFromName(userIdParam);      // Get a "stub" that allows you to call that Durable Object      let durableObjectStub = env.YOUR_DO_CLASS.get(durableObjectId);
      // Pass the request to that Durable Object and await the response      // This invokes the constructor once on your Durable Object class (defined further down)      // on the first initialization, and the fetch method on each request.      // We pass the original Request to the Durable Object's fetch method      let response = await durableObjectStub.fetch(req);
      // This would return "wrote to queue", but you could return any response.      return response;    }  }
}

export class YourDurableObject implements DurableObject {  constructor(public state: DurableObjectState, env: Env) {      this.state = state;      // Ensure you pass your bindings and environment variables into      // each Durable Object when it is initialized      this.env = env;    }  }
  async fetch(request: Request) {    // Error handling elided for brevity.    // Publish to your queue    await this.env.YOUR_QUEUE.send({      id: this.state.id // Write the ID of the Durable Object to your queue      // Write any other properties to your queue    });
    return new Response("wrote to queue")  }