TypeScript Standard Endpoints

Declarative, strongly typed, reusable network definitions for networking libraries.

1) Define the function

import { Endpoint } from '@rest-hooks/endpoint';

const fetchUser = ({ id }) ⇒ fetch(`/users/${id}`).then(res => res.json());
const UserDetail = new Endpoint(fetchUser);

2) Reuse with different hooks

function UserProfile() {
  const user = useResource(UserDetail, { id });
  const updateUser = useFetcher(UserDetail);

  return <UserForm user={user} onSubmit={updateUser} />
}

3) Or call directly

const user = await UserDetail({ id: '5' });
console.log(user);

Why

There is a distinction between

• What are networking API is
  • How to make a request, expected response fields, etc.
• How it is used
  • Binding data, polling, triggering imperative fetch, etc.

Thus, there are many benefits to creating a distinct seperation of concerns between these two concepts.

With TypeScript Standard Endpoints, we define a standard for declaring in TypeScript the definition of a networking API.

• Allows API authors to publish npm packages containing their API interfaces
• Definitions can be consumed by any supporting library, allowing easy consumption across libraries like Vue, React, Angular
• Writing codegen pipelines becomes much easier as the output is minimal
• Product developers can use the definitions in a multitude of contexts where behaviors vary
• Product developers can easily share code across platforms with distinct behaviors needs like React Native and React Web

What's in an Endpoint

• A function that resolves the results
• A function to uniquely store those results
• Optional: information about how to store the data in a normalized cache
• Optional: whether the request could have side effects - to prevent repeat calls

API

@rest-hooks/endpoint defines a standard interface

interface EndpointInterface {
    (params?: any, body?: any): Promise<any>;
    key(parmas?: any): string;
    schema?: Readonly<S>;
    sideEffects?: true;
    // other optionals like 'optimistic'
}

as well as a helper class to make construction easier.

class Endpoint<F extends () => Promise<any>> {
  constructor(fetchFunction: F, options: EndpointOptions);

  key(...args: Parameters<F>): string;

  readonly sideEffect?: true;

  readonly schema?: Schema;

  fetch: F;

  extend(options: EndpointOptions): Endpoint;
}

export interface EndpointOptions extends EndpointExtraOptions {
  key?: (params: any) => string;
  sideEffect?: true | undefined;
  schema?: Schema;
}

EndpointOptions

key: (params) => string

Serializes the parameters. This is used to build a lookup key in global stores.

Default:

`${this.fetch.name} ${JSON.stringify(params)}`

sideEffect: true | undefined

Disallows usage in hooks like useResource() since they might call fetch an unpredictable number of times. Use this for APIs with mutation side-effects like update, create, deletes.

Defaults to undefined meaning no side effects.

schema: Schema

Declarative definition of where Entities appear in the fetch response.

Not providing this option means no entities will be extracted.

import { Entity } from '@rest-hooks/normalizr';
import { Endpoint } from '@rest-hooks/endpoint';

class User extends Entity {
  readonly id: string = '';
  readonly username: string = '';

  pk() { return this.id;}
}

const UserDetail = new Endpoint(
    ({ id }) ⇒ fetch(`/users/${id}`),
    { schema: User }
);

Endpoint

extend(EndpointOptions): Endpoint

Can be used to further customize the endpoint definition

const UserDetail = new Endpoint(({ id }) ⇒ fetch(`/users/${id}`));


const UserDetailNormalized = UserDetail.extend({ schema: User });

Index

export interface IndexInterface<S extends typeof Entity> {
  key(parmas?: Readonly<IndexParams<S>>): string;
  readonly schema: S;
}

import { Entity } from '@rest-hooks/normalizr';
import { Index } from '@rest-hooks/endpoint';

class User extends Entity {
  readonly id: string = '';
  readonly username: string = '';

  pk() { return this.id;}
  static indexes = ['username'] as const;
}

const UserIndex = new Index(User)

const bob = useCache(UserIndex, { username: 'bob' });

// @ts-expect-error Indexes don't fetch, they just retrieve already existing data
const bob = useResource(UserIndex, { username: 'bob' });