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

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/durable-objects/llms.txt  
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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://developers.cloudflare.com/durable-objects/api/sqlite-storage-api/), or by storing your data elsewhere.

* [  JavaScript ](#tab-panel-8662)
* [  Python ](#tab-panel-8663)

JavaScript

```
import { DurableObject } from "cloudflare:workers";
// Workerexport 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 Objectexport 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

```
from workers import DurableObject, Response, WorkerEntrypoint
# Workerclass 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 Objectclass 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://developers.cloudflare.com/durable-objects/get-started/#4-configure-durable-object-bindings) and [migration](https://developers.cloudflare.com/durable-objects/reference/durable-objects-migrations/) based on the namespace and class name chosen previously.

* [  wrangler.jsonc ](#tab-panel-8664)
* [  wrangler.toml ](#tab-panel-8665)

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

```
"$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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