mobx-rest

REST conventions for mobx.

Table of Contents

• Installation
• What is it?
• Full React example
• Documentation
  • Model
  • Collection
  • apiClient
• Simple Example
• State shape
• FAQ
• Where is it used?
• License

Installation

npm install mobx-rest --save

What is it?

An application state is usually divided into three realms:

• Component state: Each component can have their own state, like a button being pressed, a text input value, etc.
• Application state: Sometimes we need components to share state between them and they are too far away to actually make them talk each other through props.
• Resources state: Other times, state is persisted in the server. We synchronize that state through APIs that consume resources. One way to synchronize this state is through REST.

MobX is an excellent state management choice to deal with those three realms: It allows you to represent your state as a graph while other solutions, like Redux for instance, force you to represent your state as a tree.

With mobx-rest resources are implemented with all their REST actions built in (create, fetch, save, destroy, ...) so instead of writing, over and over, hundreds of lines of boilerplate we can leverage REST conventions to minimize the code needed for your API interactions.

Full React example

If you want to see a full example with React you can check out the mobx-rest-example repo. The demo is deployed here.

Documentation

mobx-rest is fairly simple and its source code could be read in 5 minutes.

Model

A Model represents one resource. It's identified by a primary key (mandatory) and holds its attributes. You can create, update and destroy models in the client and then sync them with the server. Apart from its attributes, a Model also holds the state of the interactions with the server so you can react to those easily (showing loading states for instance).

constructor(attributes: Object)

Initialize the model with the given attributes.

defaultAttributes: Object

An object literal that holds the default attributes of the model. {} by default.

attributes: ObservableMap

An ObservableMap that holds the attributes of the model in the client.

commitedAttributes: ObservableMap

An ObservableMap that holds the attributes of the model in the server.

collection: ?Collection

A pointer to a Collection. By having models "belong to" a collection you can take the most out of mobx-rest.

toJS(): Object

Return the object version of the attributes.

primaryKey: string

Implement this abstract method so mobx-rest knows what to use as a primary key. It defaults to 'id' but if you use something like mongodb you can change it to '_id'.

urlRoot(): string

Implement this abstract method so mobx-rest knows where its API points to. If the model belongs to a Collection (setting the collection attribute) this method does not need to be implemented.

url(): string

Return the url for that given resource. Will leverage the collection's base url (if any) or urlRoot. It uses the primary id since that's REST convention.

Example: tasks.get(34).url() // => "/tasks/34"

changedAttributes: Array

Get an array with the attributes names that have changed.

Example:

model.set({ name: 'Pau'})

model.changedAttributes // => ['name']

changes: { [string]: any }

Gets the current changes.

Example:

model.set({ name: 'Pau'})

model.changes // => { name: 'Pau' }

hasChanges(attribute?: string): boolean

If an attribute is specified, returns true if it has changes. If no attribute is specified, returns true if any attribute has changes.

Example:

model.set({ name: 'Pau'})

// with attribute
model.hasChanges('name') // => true

// without attribute
model.hasChanges() // => true

commitChanges(): void

Commit attributes to model.

Example:

model.set({ name: 'Pau' })
model.hasChanges // => true

model.commitChanges()
model.hasChanges // => false

discardChanges(): void

This will reset the model attributes to the last committed ones.

Example:

const model = new Model({ name: 'Foo' })
model.set({ name: 'Pau' })
model.get('name') // => Pau

model.discardChanges()
model.get('name') // => 'Foo'

isNew: boolean

Return whether that model has been synchronized with the server or not. Resources created in the client side (optimistically) don't have an id attribute yet (that's given by the server)

Example:

const user = new User({ name : 'Pau' })
user.isNew // => true
user.save()
user.isNew // => false
user.get('id') // => 1

get(attribute: string): any

Get the given attribute. If the attribute does not exist, it will throw an error.

If different resources have different schemas you can always use has to check whether a given attribute exists or not.

Example:

if (user.has('role')) {
  return user.get('role')
} else {
  return 'basic'
}

has(attribute: string): boolean

Check that the given attribute exists.

set(data: Object): void

Update the attributes in the client.

Example:

const folder = new Folder({ name : 'Trash' })
folder.get('name') // => 'Trash'
folder.set({ name: 'Rubbish' })
folder.get('name') // => 'Rubbish'

fetch(options): Promise

Fetches this resource's data from the server.

Example:

const task = new Task({ id: 3 })
const promise = task.fetch()
await promise
task.get('name') // => 'Do the laundry'

save(attributes: Object, options: Object): Promise

The opposite of fetch. It takes the resource from the client and persists it in the server through the API. It accepts some attributes as the first argument so you can use it as a set + save. It tracks the state of the request using the label saving. If the model has a collection associated, it will be added into it.

Options:

• optimistic = true Whether we want to update the resource in the client first or wait for the server's response.
• patch = true Whether we want to use the PATCH verb and semantics, sending only the changed attributes instead of the whole resource down the wire.
• keepChanges = false Whether we want to keep the changes after the response from the API.
• path (Optional) Target API path where we want perform the save action. It has preference over url().

Example:

const company = new Company({ name: 'Teambox' })
const promise = company.save({ name: 'Redbooth' }, { optimistic: false })
company.get('name') // => 'Teambox'
await promise
company.get('name') // => 'Redbooth'

destroy(options: Object): Promise

Tells the API to destroy this resource.

Options:

• optimistic = true Whether we want to delete the resource in the client first or wait for the server's response.
• path (Optional) Target API path where we want perform the save action. It has preference over url().

rpc(method: 'string', body?: {}, label?: 'fetching'): Promise

When dealing with REST there are always cases when we have some actions beyond the conventions. Those are represented as rpc calls and are not opinionated.

Example:

const response = await task.rpc('resolveSubtasks', { all: true })
if (response.ok) {
  task.subTasks.fetch()
}

Collection

A Collection represents a group of resources. Each element of a Collection is a Model. Likewise, a collection tracks also the state of the interactions with the server so you can react accordingly.

models: ObservableArray

An ObservableArray that holds the collection of models.

indexes: Array<String>

Indexes allow you to determine which attributes you want to index your collection by. This allows you to trade-off memory for speed. By default we index all the models by primaryKey but you can add more indexes that will be used automatically when using filter and find with the object form.

users.find({ id: 123 }) // This will hit the index. Fast!
users.find(user => user.get('id') === 123) // This will do a full scan of the table. Slow.

You can query your collection by a combination of attributes that are indexed and others that are not indexed. mobx-rest will take care to sort your query in order to scan the least number of models.

constructor(data: Array<Object>)

Initializes the collection with the given resources.

url(): string

Abstract method that must be implemented if you want your collection and it's models to be able to interact with the API.

model(): Model

Abstract method that tells which kind of Model objects this collection holds. This is used, for instance, when doing a collection.create so we know which object to instantiate.

toJS(): Array<Object>

Return a plain data structure representing the collection of resources without all the observable layer.

toArray(): Array<ObservableMap>

Return an array with the observable resources.

isEmpty: boolean

Helper method that asks the collection whether there is any model in it.

Example:

const promise = usersCollection.fetch()
usersCollection.isEmpty // => true
await promise
usersCollection.isEmpty // => false
usersCollection.models.length // => 10

at(index: number): ?Model

Find a model at the given position.

get(id: number, { required?: boolean = false }): ?Model

Find a model (or not) with the given id. If required it will raise an error if not found.

filter(query: Object | Function): Array<Model>

Helper method that filters the collection by the given conditions represented as a key value.

Example:

// using a query object
const resolvedTasks = tasksCollection.filter({ resolved: true })
resolvedTasks.length // => 3

// using a query function
const resolvedTasks = tasksCollection.filter(model => model.resolved)
resolvedTasks.length // => 3

It's important to notice that using the object API we can optimize the filtering using indexes.

find(query: Object | Function, { required?: boolean = false }): ?Model

Same as filter but it will halt and return when the first model matches the conditions. If required it will raise an error if not found.

Example:

// using a query object
const user = usersCollection.find({ name: 'paco' })
user.get('name') // => 'paco'

// using a query function
const user = usersCollection.find(model => model.name === 'paco')
user.get('name') // => 'paco'

usersCollection.find({ name: 'foo'}) // => Error(`Invariant: Model must be found`)

last(): ?Model

Returns the last model of the collection. If the collection is empty, it returns null

add(data: Array<Object|T>|T|Object): Array<Model>

Adds models with the given array of attributes.

usersCollection.add([{id: 1, name: 'foo'}])

reset(data: Array<Object|T>): Array<Model>

Resets the collection with the given models.

usersCollection.reset([{id: 1, name: 'foo'}])

remove(ids: Array<number|T>|number|T): void

Remove any model with the given ids.

Example:

usersCollection.remove([1, 2, 3])

set(models: Array<Object | Model>, options: Object): void

Merge the given models smartly the current ones in the collection. It detects what to add, remove and change.

Options:

• add = true Change to disable adding models
• change = true Change to disable updating models
• remove = true Change to disable removing models

const companiesCollection = new CompaniesCollection([
  { id: 1, name: 'Teambox' }
  { id: 3, name: 'Zpeaker' }
])
companiesCollection.set([
  { id: 1, name: 'Redbooth' },
  { id: 2, name: 'Factorial' }
])
companiesCollection.get(1).get('name') // => 'Redbooth'
companiesCollection.get(2).get('name') // => 'Factorial'
companiesCollection.get(3) // => null

build(attributes: Object|T): Model

Instantiates and links a model to the current collection.

const factorial = companiesCollection.build({ name: 'Factorial' })
factorial.collection === companiesCollection // => true
factorial.get('name') // 'Factorial'

create(target: Object | Model, options: Object)

Add and save to the server the given model. If attributes are given, also it builds the model for you. It tracks the state of the request using the label creating.

Options:

• optimistic = true Whether we want to create the resource in the client first or wait for the server's response.
• path (Optional) Target API path where we want perform the save action. It has preference over url().

const promise = tasksCollection.create({ name: 'Do laundry' })
await promise
tasksCollection.at(0).get('name') // => 'Do laundry'

fetch(options: Object)

Fetch the date from the server and then calls set to update the current models. Accepts any option from the set method.

const promise = tasksCollection.fetch()
tasksCollection.isEmpty // => true
await promise
tasksCollection.isEmpty // => false

rpc(method: 'string', body: {}): Promise

Exactly the same as the model one, but at the collection level.

forEach (callback: (model: T) => void): void

Alias for models.forEach

Example: collection.forEach(model => console.log(model.get('id')))

map

(callback: (model: T) => P): Array

Alias for models.map

Example: collection.map(model => model.get('id')) // => [1,2,3...]

peek (): Array<T: Model>

Returns a shallow array representation of the collection

slice (): Array<T: Model>

Returns a defensive shallow array representation of the collection

apiClient

This is the object that is going to make the xhr requests to interact with your API. There are currently three implementations:

• One using jQuery in the mobx-rest-jquery-adapter package.
• One using fetch in the mobx-rest-fetch-adapter package.
• One Using axios in the mobx-rest-axios-adapter package.

Initially you need to configure apiClient() with an adapter and the apiPath. You can also set additional options, like headers to send with all requests.

For example, if you're using JWT and need to send it using the Authorization header, it could look like this:

const options = {
  apiPath: window.env.apiUrl,
}
if (token) {
  options.commonOptions = {
    headers: {
      Authorization: `Bearer ${token}`
    }
  }
}
apiClient(adapter, options)

All options:

• apiPath (required): what do prepend for all model and collections URLs
• commonOptions: settings to use for all requests
  • headers: Additional request headers, like Authorization
  • tbd.

Simple Example

A collection looks like this:

// TasksCollection.js
const apiPath = '/api'
import adapter from 'mobx-rest-fetch-adapter'
import { apiClient, Collection, Model } from 'mobx-rest'

// We will use the adapter to make the `xhr` calls
apiClient(adapter, { apiPath })

class Task extends Model { }
class Tasks extends Collection {
  url ()  { return `/tasks` }
  model () { return Task }
}

// We instantiate the collection and export it as a singleton
export default new Tasks()

And here an example of how to use React with it:

import tasksCollection from './TasksCollection'
import { computed } from 'mobx'
import { observer } from 'mobx-react'

@observer
class Task extends React.Component {
  onClick () {
    this.props.task.save({ resolved: true })
  }

  render () {
    return (
      <li key={task.id}>
        <button onClick={this.onClick.bind(this)}>
          resolve
        </button>
        {this.props.task.get('name')}
      </li>
    )
  }
}

@observer
class Tasks extends React.Component {
  componentDidMount () {
    // This will call `/api/tasks?all=true`
    tasksCollection.fetch({ data: { all: true } })
  }

  @computed
  get activeTasks () {
    return tasksCollection.filter({ resolved: false })
  }

  render () {
    return (
      <div>
        <span>{this.activeTasks.length} tasks</span>
        <ul>{activeTasks.map((task) => <Task task={task} />)}</ul>
      </div>
    )
  }
}

State shape

Your collections and models will have the following state shape:

Collection

models: Array<Model>      // This is where the models live

Model

attributes: Object    // The resource attributes
optimisticId: string, // Client side id. Used for optimistic updates

FAQ

How do I create relations between the models?

This is something that mobx makes really easy to achieve:

import users from './UsersCollections'
import comments from './CommentsCollections'
import { computed } from 'mobx'

class Task extends Model {
  @computed
  author () {
    return users.get(this.get('user_id'))
  }

  @computed
  comments () {
    return comments.filter({ task_id: this.get('id') })
  }
}

Where is it used?

Developed and battle tested in production in Factorial

License

(The MIT License)

Copyright (c) 2022 Pau Ramon masylum@gmail.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.