Devour JSON-API Client

– _"Don't just consume your JSON-API, Devour it"_

-------------------------------------------------

The JSON API specification has given us a sensible convention to build our API's against.
It's flexible, well thought out, and comes fully loaded with clear answers to questions like pagination, filtering,
sparse fields, and relationships.

While JSON API is amazing, it can be painful to work with if you don't have a good consumer library. It turns out that
serializing and deserializing JSON API resources manually is quite painful. Enter Devour...

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While there are quite a few TypeScript client implementations,
none of them appeared to offer the exact feature set we needed with the simplicity we required.

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``
$ npm install devour-client-ts
`

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`js
// Import
import { JsonApi } from 'devour-client-ts'
import { LogLevel } from 'devour-client-ts/lib/logger'

// Bootstrap
const jsonApi: JsonApi = new JsonApi({apiUrl:'http://your-api-here.com', loglevel: LogLevel.WARN})

// Define Model
jsonApi.define('post', {
title: '',
content: '',
tags: []
})

// To find many...
jsonApi.findAll('post')

// To find many with filters...
jsonApi.findAll('post', {page: {number: 2}})

// To find one...
jsonApi.find('post', 5)

// To create...
jsonApi.create('post', {
title: 'hello',
content: 'some content',
tags: ['one', 'two']
}, {
include: 'tags'
})

// To update...
jsonApi.update('post', {
id: 5,
title: 'new title',
content: 'new content',
tags: ['new tag']
}, {
include: 'tags'
})

// To destroy...
jsonApi.destroy('post', 5)

// To make arbitrary requests through the middleware stack
jsonApi.request('https://example.com', 'GET', { a_query_param: 3 }, { some_payload_item: 'blah' })
`

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const jsonApi: JsonApi = new JsonApi({apiUrl: 'http://your-api-here.com'})

Devour takes an object as the initializer. The following options are available:

apiUrl: The HTTP API end point, for example: http://your-api-here.com

middleware: An array of middleware to use. See below

logger: A boolean to enable or disable the logger. (Default: true)

loglevel: The log level to use. (Default: LogLevel.INFO)

pluralize: A function like pluralize, or false to disable pluralization. (Default: require('pluralize'))

resetBuilderOnCall: A boolean to clear the builder stack after a .get, .post, .patch, .destroy call. (Default: true)

auth: An object with username and password, used to pass in HTTP Basic Authentication Headers, new JsonApi({apiUrl: 'http://your-api-here.com', auth: {username: 'secret', password: 'cheesecake'})

bearer: A string containing the bearer token, used to add a HTTP Authorization Header new JsonApi({apiUrl: 'http://your-api-here.com', bearer: 'your-token-here'})

trailingSlash: An optional object to use trailing slashes on resource and/or collection urls (defaults to false), new JsonApi({apiUrl: 'http://your-api-here.com', trailingSlash: {resource: false, collection: true})

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Devour comes stock with an easy way of defining relationships which can be included when hitting your API.

``js
jsonApi.define('post', {
title: '',
content: '',
comments: {
jsonApi: 'hasMany',
type: 'comments'
}
})

jsonApi.define('comment', {
comment: ''
})

let { data, errors, meta, links } = jsonApi.findAll('post', {include: 'comments'})
// => data.comment will be populated with any comments included by your API
`

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Devour uses a fully middleware based approach. This allows you to easily manipulate any part of the request and response cycle by injecting your own middleware. In fact, it's entirely possible to fully remove our default middleware and write your own. Moving forward we hope to see adapters for different server implementations. If you'd like to take a closer look at the middleware layer, please checkout:

* The jsonapi.ts file where we construct our default middleware stack
* The middleware folder that contains all our default JSON API middleware

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Adding your own middleware is easy. It's just a simple JavaScript object that has a name, req, and/or res property. The name property must be the unique name of your middleware. The req or res property is a function that receives a payload, which houses all the details of the request cycle _(see documentation below)_. For async operations, your req or res methods can return a promise, which will need to resolve before the middleware chain continues. Otherwise, you may just manipulate the payload as needed and return it immediately.

`js
let requestMiddleware = {
name: 'add-cats-to-request',
req: (payload)=> {
if(payload.req.method === 'GET') {
payload.req.cats = 'more-cats'
}
return payload
}
}

let responseMiddleware = {
name: 'only-cats-please',
res: (payload) => {
payload.res.data = ['Cats', 'Cats', 'Cats']
return payload
}
}

let errorMiddleware = {
name: 'nothing-to-see-here',
error: function (payload) {
return { errors: [] }
}
}

jsonApi.insertMiddlewareBefore('axios-request', requestMiddleware)
jsonApi.insertMiddlewareAfter('response', responseMiddleware)
jsonApi.replaceMiddleware('errors', errorMiddleware)
jsonApi.removeMiddleware('response')
`

#### The payload object

The payload object that gets passed to your middleware function has the following shape:

* data - JSON data contained in request/response body
* headers - An object containing the headers for the request/response
* method - A string representing the HTTP verb used, e.g. 'GET' or 'PATCH'
* model - The model that initiated this request
* params - An object containing the keys/values passed in the query params of the request
* url - The URL to which the request was sent

The payload for response middleware contains these additional fields:

* config - An object of low-level config data
* request - The original XMLHttpRequest object used to make the request
* status - HTTP status code for the request, e.g. 200
* statusText - Text representation of the HTTP status, e.g. "OK", "Created"

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This request middleware may be handy for live queries as it permits the last pending request to be cancelled
(via Axios request cancellation feature).

`
let cancellableRequest = {
name: 'axios-cancellable-request',
req: function (payload) {
let jsonApi = payload.jsonApi
return jsonApi.axios(payload.req, {
cancelToken: new jsonApi.axios.CancelToken(function executor(c) {
// An executor function receives a cancel function as a parameter
jsonApi.cancel = c;
})
})
}
}

jsonApi.replaceMiddleware('axios-request', cancellableRequest)

// jsonApi.cancel() will cancel the last pending request
`

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When declaring a model you may pass in a few extra options. We will likely expand these options as we find new and
interesting requirements.

`js
jsonApi.define('product', {
title: '',
description: '',
price: ''
}, {
readOnly: ['price'],
collectionPath: 'awesome-products',
serializer: (rawItem)=> {
return {customStuff: true}
},
deserializer: (rawItem)=> {
return {customStuff: true}
}
})
`

There are also a few options we can set on the jsonApi instance directly. For example:

`js
// Append headers to every request
jsonApi.headers['my-auth-token'] = 'xxxxx-xxxxx'

// Replace the default middleware stack with your own
jsonApi.middleware = [{...}, {...}, {...}]

// Change the apiUrl
jsonApi.apiUrl = 'http://api.yoursite.com'

// Use custom error builder
jsonApi.errorBuilder = (error) => {
// add 'meta' in addition to title and detail
const { title, detail, meta } = error
return { title, detail, meta }
}
`

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JSON API Specs allows nested URLs to be used to define a resource. For example, /authors/1/posts may define posts
from author with ID 1.

The builder pattern allows arbitrary nested URL construction by chaining .one(model, id) and .all(model) and append
an action, one of: .get, .post, .patch and .destroy

For example:

`js
let jsonApi = new JsonApi({apiUrl: 'http://api.yoursite.com'})
jsonApi.define('author', {name: ''})
jsonApi.define('post', {title: ''})

jsonApi.one('author', 1).all('post').get({include: 'books'}) // GET http://api.yoursite.com/authors/1/posts?include=books
jsonApi.one('author', 1).all('post').post({title:'title'}, {include: 'books'}) // POST http://api.yoursite.com/authors/1/posts?include=books
`

JSON API Specs also allow the _relationships_ between resources to be created, updated and deleted.
For example, /authors/1/relationships/posts defines the relationships between an author and its post.
You can use .patch, .post and .delete to edit relationships
(read more).

For example:

`js
let jsonApi = new JsonApi({apiUrl: 'http://api.yoursite.com'})
jsonApi.define('author', {name: '', articles: { jsonApi: 'hasMany', type: 'post' } })
jsonApi.define('post', {title: ''})

jsonApi.create('author', { name: 'Joanna Blogs' }) // Create an author
jsonApi.create('post', { title: 'How to Make Relationships' }) // Create a post

// Create a relationship between the author and the post
jsonApi.one('author', 1).relationships('articles').patch([{ id: 1 }])
`

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To specify a polymorphic relationship, simply define a model with a polymorphic relationship without specifying its type.

`js
jsonApi.define('order', {
name: '',
payables: {
jsonApi: 'hasMany'
}
})

let payables = [{id: 4, type: 'subtotal'}, {id: 5, type: 'tax'}]
jsonApi.all('order').post({ name: 'first', payables }).subscribe(({ data, errors, meta, links }) => { / ... / })
/* => POST http://api.yoursite.com/orders
{
type: orders,
attributes: {
name: 'first'
},
relationships: {
payables: {
data: [
{ id: 4, type: 'subtotal' },
{ id: 5, type: 'tax' }
]
}
}
} */
`

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* 1.1.0: Promises are now Observables (rxjs@7.4.0`)