Durable Object 内存状态

此示例展示 Durable Objects 是有状态的，意味着内存状态可以在请求之间保留。在短暂不活动后，Durable Object 将被驱逐，所有内存状态将丢失。下一个请求将重建对象，但不会显示上一个请求的城市，而是显示对象已重新初始化的消息。如果您需要应用状态在驱逐后存活，请使用 Storage API 将状态写入存储，或将数据存储在其他地方。

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);
	}
}

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)

最后，配置 Wrangler 文件以包含基于先前选择的 namespace 和类名称的 Durable Object 绑定和迁移。

{
	"$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"
			]
		}
	]
}

"$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" ]