---
title: Durable Object in-memory state
description: Create a Durable Object that stores the last location it was accessed from in-memory.
image: https://edgetunnel-b2h.pages.dev/dev-products-preview.png
---

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# Durable Object in-memory state

Create a Durable Object that stores the last location it was accessed from in-memory.

This example shows you how Durable Objects are stateful, meaning in-memory state can be retained between requests. After a brief period of inactivity, the Durable Object will be evicted, and all in-memory state will be lost. The next request will reconstruct the object, but instead of showing the city of the previous request, it will display a message indicating that the object has been reinitialized. If you need your applications state to survive eviction, write the state to storage by using the [Storage API](https://edgetunnel-b2h.pages.dev/durable-objects/api/sqlite-storage-api/), or by storing your data elsewhere.

* [  JavaScript ](#tab-panel-9024)
* [  Python ](#tab-panel-9025)

**JavaScript**

```js
import { DurableObject } from "cloudflare:workers";


// Worker
export default {
  async fetch(request, env) {
    return await handleRequest(request, env);
  },
};


async function handleRequest(request, env) {
  let stub = env.LOCATION.getByName("A");
  // Forward the request to the remote Durable Object.
  let resp = await stub.fetch(request);
  // Return the response to the client.
  return new Response(await resp.text());
}


// Durable Object
export class Location extends DurableObject {
  constructor(state, env) {
    super(state, env);
    // Upon construction, you do not have a location to provide.
    // This value will be updated as people access the Durable Object.
    // When the Durable Object is evicted from memory, this will be reset.
    this.location = null;
  }


  // Handle HTTP requests from clients.
  async fetch(request) {
    let response = null;


    if (this.location == null) {
      response = new String(`
This is the first request, you called the constructor, so this.location was null.
You will set this.location to be your city: (${request.cf.city}). Try reloading the page.`);
    } else {
      response = new String(`
The Durable Object was already loaded and running because it recently handled a request.


Previous Location: ${this.location}
New Location: ${request.cf.city}`);
    }


    // You set the new location to be the new city.
    this.location = request.cf.city;
    console.log(response);
    return new Response(response);
  }
}
```

**Python**

```py
from workers import DurableObject, Response, WorkerEntrypoint


# Worker
class Default(WorkerEntrypoint):
  async def fetch(self, request):
    return await handle_request(request, self.env)


async def handle_request(request, env):
  stub = env.LOCATION.getByName("A")
  # Forward the request to the remote Durable Object.
  resp = await stub.fetch(request)
  # Return the response to the client.
  return Response(await resp.text())


# Durable Object
class Location(DurableObject):
  def __init__(self, ctx, env):
    super().__init__(ctx, env)
    # Upon construction, you do not have a location to provide.
    # This value will be updated as people access the Durable Object.
    # When the Durable Object is evicted from memory, this will be reset.
    self.location = None


  # Handle HTTP requests from clients.
  async def fetch(self, request):
    response = None


    if self.location is None:
      response = f"""
This is the first request, you called the constructor, so this.location was null.
You will set this.location to be your city: ({request.js_object.cf.city}). Try reloading the page."""
    else:
      response = f"""
The Durable Object was already loaded and running because it recently handled a request.


Previous Location: {self.location}
New Location: {request.js_object.cf.city}"""


    # You set the new location to be the new city.
    self.location = request.js_object.cf.city
    print(response)
    return Response(response)
```

Finally, configure your Wrangler file to include a Durable Object [binding](https://edgetunnel-b2h.pages.dev/durable-objects/get-started/#4-configure-durable-object-bindings) and [migration](https://edgetunnel-b2h.pages.dev/durable-objects/reference/durable-objects-migrations/) based on the namespace and class name chosen previously.

* [  wrangler.jsonc ](#tab-panel-9026)
* [  wrangler.toml ](#tab-panel-9027)

**JSONC**

```jsonc
{
  "$schema": "./node_modules/wrangler/config-schema.json",
  "name": "durable-object-in-memory-state",
  "main": "src/index.ts",
  "durable_objects": {
    "bindings": [
      {
        "name": "LOCATION",
        "class_name": "Location"
      }
    ]
  },
  "migrations": [
    {
      "tag": "v1",
      "new_sqlite_classes": [
        "Location"
      ]
    }
  ]
}
```

**TOML**

```toml
"$schema" = "./node_modules/wrangler/config-schema.json"
name = "durable-object-in-memory-state"
main = "src/index.ts"


[[durable_objects.bindings]]
name = "LOCATION"
class_name = "Location"


[[migrations]]
tag = "v1"
new_sqlite_classes = [ "Location" ]
```

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