halboy-ts

An intuitive HAL+JSON library.

---

Install

npm:
npm i halboy-ts

yarn:
yarn add halboy-ts

pnpm:
pnpm add halboy-ts

Usage

Resources

Resources are immutable by default. This means that any operation that would change the state of a resource will return a new resource with the changes applied and leaves the previous resource untouched.

const resource = Resource.create('https://example.com/things/123')
//.addProperty creates a new resource and leaves 'resource' untouched
const differentResource = resource.addProperty('a', 1)

Creating Resource through DSL

Basic example

import { Resource } from 'halboy-ts'

const resource = Resource.create('https://example.com/things/123').addProperty(
  'someProp',
  'hello, world!',
)

console.log(resource.getProperty('someProp')) // hello, world!

Adding self link

Self links can be added directly through the create method. This is semantically equivalent to calling addLink with the self relation.

import { Resource } from 'halboy-ts'

//both are equivalent
Resource.create('https://example.com/things/123')
Resource.create().addLink('self', 'https://example.com/things/123')

Adding links

Links can be added individually or in a batch. Links can also be added in a simplified manner by just passing a string or as a Link object.
The former exists for convenience and will create a Link object with the relation relation.

import { Resource } from 'halboy-ts'

Resource.create()
  .addLink('foo', 'https://example.com/foos/1')
  .addLink('bar', 'https://example.com/bars/2')

Resource.create().batchAddLinks({
  foo: 'https://example.com/foos/1',
  bar: 'https://example.com/bars/2',
})

//This allows for adding additional link properties as defined in the spec.
Resource.create().addLink('foo', { href: 'https://example.com/foos/1' })

Adding properties

Properties can be added individually or in a batch.

import { Resource } from 'halboy-ts'

Resource.create().addProperty('a', 1).addProperty('b', 2)

Resource.create().batchAddProperties({ a: 1, b: 2 })

Accessing properties

The simplest way to access properties is through the getProperty method.

import { Resource } from 'halboy-ts'

const resource = Resource.create().add('a', 1)

resource.getProperty('a')

Be mindful that this method returns type Property. Which is a built-in type. If you want to cast to a specific type on access you can pass a type parameter to getProperty.

import { Resource } from 'halboy-ts'

const resource = Resource.create().add('a', 1)

const a: number = resource.getProperty<number>('a')

[!CAUTION]
This is only to appease the type system. No checks are done to validate if the property is actually of that type.

Creating Resource from JSON

import { Resource } from 'halboy-ts'

const resource = Resource.fromObject({
  someProp: 'hello, world!',
  _links: {
    otherThing: { href: 'https://example.com/other-things/456' },
  },
})

console.log(resource.getProperty('someProp')) // hello, world!
console.log(resource.getHref('otherThing')) //https://example.com/other-things/456

Creating object from Resource for usage on wire

import { Resource } from 'halboy-ts'

const resource = Resource.create('https://example.com/things/123')
  .addLink('otherThing', 'https://example.com/other-things/456')
  .addProperty('someProp', 'hello, world!')

console.log(resource.toObject())

//output
//{
//  someProp: 'hello, world!',
//  _links: {
//    otherThing: { href: 'https://example.com/other-things/456' }
//  }
//}

Navigator

The Navigator class is used to navigate through a HAL+JSON API. It is used to fetch resources and perform operations on them.
The starting point for every interaction with an API should be the discover method.

import { Navigator } from 'halboy-ts'

const navigator = await Navigator.discover(url)

//navigator provides `status` and `resource` properties based on the result of the underlying network call

Navigating to relations

One the API was discovered relations can be navigated to with the respective http-method-based methods.

const navigator = await Navigator.discover(url).then((navigator) =>
  navigator.get('aRelation'),
)

If any of the calls in the chain fail the result will be passed through the chain without making further network calls.

const navigator = await Navigator.discover(url) //Discovery failed!
  .then((navigator) => navigator.get('aRelation')) //This call will not be made

navigator.status //status code from discovery call

TODO

• Resource

  • links
    • support for other link props
  • embedded
    • batch adding resources

• Navigator

  • patch
  • put
  • http options
  • support for link templates as per RFC 6570

• Test Support