---
title: Use Workers KV from Durable Objects
description: Read and write to/from KV within a Durable Object
image: https://developers.cloudflare.com/dev-products-preview.png
---

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# Use Workers KV from Durable Objects

Read and write to/from Workers KV within a Durable Object

The following Worker script shows you how to configure a Durable Object to read from and/or write to a [Workers KV namespace](https://developers.cloudflare.com/kv/concepts/how-kv-works/). This is useful when using a Durable Object to coordinate between multiple clients, and allows you to serialize writes to KV and/or broadcast a single read from KV to hundreds or thousands of clients connected to a single Durable Object [using WebSockets](https://developers.cloudflare.com/durable-objects/best-practices/websockets/).

Prerequisites:

* A [KV namespace](https://developers.cloudflare.com/kv/api/) created via the Cloudflare dashboard or the [wrangler CLI](https://developers.cloudflare.com/workers/wrangler/install-and-update/).
* A [configured binding](https://developers.cloudflare.com/kv/concepts/kv-bindings/) for the `kv_namespace` in the Cloudflare dashboard or Wrangler file.
* A [Durable Object namespace binding](https://developers.cloudflare.com/workers/wrangler/configuration/#durable-objects).

Configure your Wrangler file as follows:

* [  wrangler.jsonc ](#tab-panel-8702)
* [  wrangler.toml ](#tab-panel-8703)

JSONC

```
{  "$schema": "./node_modules/wrangler/config-schema.json",  "name": "my-worker",  "main": "src/index.ts",  "kv_namespaces": [    {      "binding": "YOUR_KV_NAMESPACE",      "id": "<id_of_your_namespace>"    }  ],  "durable_objects": {    "bindings": [      {        "name": "YOUR_DO_CLASS",        "class_name": "YourDurableObject"      }    ]  }}
```

TOML

```
"$schema" = "./node_modules/wrangler/config-schema.json"name = "my-worker"main = "src/index.ts"
[[kv_namespaces]]binding = "YOUR_KV_NAMESPACE"id = "<id_of_your_namespace>"
[[durable_objects.bindings]]name = "YOUR_DO_CLASS"class_name = "YourDurableObject"
```

* [  TypeScript ](#tab-panel-8700)
* [  Python ](#tab-panel-8701)

TypeScript

```
import { DurableObject } from "cloudflare:workers";
interface Env {  YOUR_KV_NAMESPACE: KVNamespace;  YOUR_DO_CLASS: DurableObjectNamespace;}
export default {  async fetch(req: Request, env: Env): Promise<Response> {    // Assume each Durable Object is mapped to a roomId in a query parameter    // In a production application, this will likely be a roomId defined by your application    // that you validate (and/or authenticate) first.    let url = new URL(req.url);    let roomIdParam = url.searchParams.get("roomId");
    if (roomIdParam) {      // Get a stub that allows you to call that Durable Object      let durableObjectStub = env.YOUR_DO_CLASS.getByName(roomIdParam);
      // 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.      //      // You could pass the original Request to the Durable Object's fetch method      // or a simpler URL with just the roomId.      let response = await durableObjectStub.fetch(`http://do/${roomId}`);
      // This would return the value you read from KV *within* the Durable Object.      return response;    }  },};
export class YourDurableObject extends DurableObject {  constructor(    public state: DurableObjectState,    env: Env,  ) {    super(state, env);  }
  async fetch(request: Request) {    // Error handling elided for brevity.    // Write to KV    await this.env.YOUR_KV_NAMESPACE.put("some-key");
    // Fetch from KV    let val = await this.env.YOUR_KV_NAMESPACE.get("some-other-key");
    return Response.json(val);  }}
```

Python

```
from workers import DurableObject, Response, WorkerEntrypointfrom urllib.parse import urlparse, parse_qs
class Default(WorkerEntrypoint):  async def fetch(self, req):    # Assume each Durable Object is mapped to a roomId in a query parameter    # In a production application, this will likely be a roomId defined by your application    # that you validate (and/or authenticate) first.    url = req.url    parsed_url = urlparse(url)    room_id_param = parse_qs(parsed_url.query).get('roomId', [None])[0]
    if room_id_param:      # Get a stub that allows you to call that Durable Object      durable_object_stub = self.env.YOUR_DO_CLASS.getByName(room_id_param)
      # 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.      #      # You could pass the original Request to the Durable Object's fetch method      # or a simpler URL with just the roomId.      response = await durable_object_stub.fetch(f"http://do/{room_id_param}")
      # This would return the value you read from KV *within* the Durable Object.      return response
class YourDurableObject(DurableObject):  def __init__(self, state, env):    super().__init__(state, env)
  async def fetch(self, request):    # Error handling elided for brevity.    # Write to KV    await self.env.YOUR_KV_NAMESPACE.put("some-key", "some-value")
    # Fetch from KV    val = await self.env.YOUR_KV_NAMESPACE.get("some-other-key")
    return Response.json(val)
```

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