@ticketbridge/hyper-durable

HyperDurable

HyperDurable is a base class for Durable Objects to enable natural, object-like access to underlying persistent storage from Durable Object stubs. HyperDurable completely abstracts the Durable Object fetch API, improving code readability in business logic layers.

• Abstracts away Durable Object fetch API
• Automatically persists dirty data
• Built with TypeScript
• Comprehensive test suite

Installation

With Yarn:

yarn add @ticketbridge/hyper-durable

With NPM:

npm i @ticketbridge/hyper-durable

Usage

Write your durable object class by extending the HyperDurable base class. In the constructor, pass the state and env to HyperDurable via super(). HyperDurable will load all previously persisted data into memory inside its fetch, so any properties you set in the constructor after calling super() will be overriden by any previously persisted data.

Inside your durable object, access properties and methods in memory using this. No need to worry about persistence- dirty data is persisted at the end of every fetch request.

// RubberDuck.js
import { HyperDurable } from '@ticketbridge/hyper-durable';

export class RubberDuck extends HyperDurable {
  constructor(state, env) {
    // Pass state and env to HyperDurable
    super(state, env);

    // Anything set here will be overriden by previously persisted data, if any exists
    // Therefore, you can safely set default values here
    this.name = 'New Duck';
    this.favoriteFoods = [];
  }

  addFavoriteFood(food) {
    this.favoriteFoods.push(food);
  }

  sayHello() {
    return `Hello world, my name is ${this.name}, and I have ${this.favoriteFoods.length} favorite foods.`;
  }
}

In your worker, first proxy your durable object namespaces with proxyHyperDurables. Obtaining a stub is unchanged: generate your id with your preferred method from the namespace API (i.e., newUniqueId, idFromName, idFromString), then use get to construct an object stub.

Every stub operation must be awaited, since they all use the fetch API under the hood. Properties can be read directly from the stub. Properties can be set with their auto-generated setters (in the format set + PropName). Methods can be called directly from the stub.

// worker.js
import { proxyHyperDurables } from '@ticketbridge/hyper-durable';
import { RubberDuck } from './RubberDuck';

// Export the DO class
export { RubberDuck };

export default {
  async fetch(request, env) {
    // Proxy the namespace
    const { RUBBERDUCK } = proxyHyperDurables(env, {
      // BINDINGNAME: DurableObjectClass
      RUBBERDUCK: RubberDuck
    });

    // Obtain a stub
    const id = RUBBERDUCK.idFromName('firstDuck');
    const stub = RUBBERDUCK.get(id);

    // Await properties
    const name = await stub.name; // 'New Duck'

    // Await setters
    const newName = await stub.setName('Special Duck'); // 'Special Duck'

    // Await methods
    await Promise.all([
      stub.addFavoriteFood('herring'),
      stub.addFavoriteFood('shrimp')
    ]);
    const greeting = await stub.sayHello(); // 'Hello world, my name is Special Duck, and I have 2 favorite foods.'
  
    return new Response(greeting);
  }
}

API

HyperDurable

Use as the base class of your durable object. Includes some properties and methods by default, which are described below.

env: Env

The env passed in the constructor.

state: HyperState

The state passed in the constructor, plus:

state.dirty: Set<string>

Set of properties that have been changed in memory but are not yet persisted.

state.persisted: Set<string>

Set of properties that are persisted in Durable Object storage.

state.tempKey: string

Used to track the key of a deeply-nested property (i.e., when accessing this.favoriteFoods[0], state.tempKey is favoriteFoods).

storage: DurableObjectStorage

Durable Object storage, from state.storage.

router: Router

An itty-router to handle incoming fetch requests.

async initialize()

Initializes loading if loading has not already begun.

async load()

Loads persisted data into memory.

async persist()

Persists dirty properties.

async destroy()

Deletes all data in storage, clears state.dirty and state.persisted, and deletes all properties from memory.

toObject()

Returns all persisted and dirty data as an object.

async fetch(request: Request): Promise<Response>

Initializes the object (if not previously initialized), then passes the request to router. After router handles the request, persists any dirty data.

proxyHyperDurables(env: Env, doBindings: { [key: string]: DOClass })

Use to proxy your durable object namespaces. Accepts two parameters: env and doBindings. env is the env of your worker where namespaces are accessed. doBindings is an object, where the keys are binding names and the values are the durable object classes associated with those binding. Returns an object, where the keys are the passed binding names and the values are the associated HyperNamespaceProxy.

HyperNamespaceProxy

Use to generate object IDs and get object stubs, just as in the upstream DurableObjectNamespace API.

HyperStub

Produced by HyperNamespaceProxy.get(id). The fetch method can be accessed directly, as in the upstream API. The stub also allows for simple access to properties and methods.

To get a property, await it:

await stub.name;

To set a property, await the auto-generated setter (returns the new value):

await stub.setName('Eendje');

To invoke a method, await it (NOTE: If a method has no return value, it will return null instead of the usual undefined):

await stub.sayHello();

Stub properties and methods will return their value directly in the event of a success. If the operation fails, a HyperError will be thrown with the following structure:

{
  message: 'Error message',
  details: 'Error details'
}

Special Thanks

This library was heavily inspired by itty-durable from Kevin Whitley.