@startupjs/react-sharedb-classes

startupjs react-sharedb-classes

Run ShareDB in React using Class syntax

What it does

1. Brings real-time collaboration to React using ShareDB;
2. Uses Racer to add a model to your app to do any data manipulations;
3. The model acts as a global singleton state, so you can use it as a replacement for other state-management systems like Redux or MobX;
4. Makes the render reactive similar to how it's done in MobX -- rerendering happens whenever any model data you used in render changes.

Installation

You don't need to install anything if you are in a StartupJS project.

For instructions on standalone usage in a pure React project refer to react-sharedb readme

Requirements

react: 16.9 - 17

Usage with Classes

@subscribe(cb) HOC

@subscribe decorator is used to specify what you want to subscribe to.

@subscribe gives react component a personal local scope model, located at path $components.<random_id>. This model will be automatically cleared when the component is unmounted.

HOW TO: Subscribe to data and use it in render()

@subscribe accepts a single argument -- cb, which receives props and must return the subscriptions object.

Each key in the subscriptions object will fetch specified data from the MongoDB or a Local path and will write it into the component's personal scope model under that key.

The read-only data of the component's model is available as this.props.store. Use it to render the data you subscribed to, same way you would use this.state.

IMPORTANT As with this.state, the this.props.store SHOULD NOT be modified directly! Read below to find out how to modify data.

Example:

import React from 'react'
import {subscribe, subLocal, subDoc, subQuery} from 'startupjs'

@subscribe(props => ({
  myUserId: subLocal('_session.userId'),
  room: subDoc('rooms', props.roomId)
}))
@subscribe(props => ({
  myUser: subDoc('users', props.store.userId),
  usersInRoom: subQuery('users', {_id: {
    $in: props.store.room && props.store.room.userIds || []
  }})
}))
export default class Room extends React.Component {
  render () {
    let {room, myUser, usersInRoom} = this.props.store
    return <Fragment>
      <h1>{room.name}</h1>
      <h2>Me: {myUser.name}</h2>
      <p>Other users in the room: {usersInRoom.map(user => user.name)}</p>
    </Fragment>
  }
}

As seen from the example, you can combine multiple @subscribe one after another.

HOW TO: Modify the data you subscribed to

The actual scoped model of the component is available as this.props.$store. Use it to modify the data. For the API to modify stuff refer to the Racer documentation

In addition, all things from subscriptions object you subscribed to are available to you as additional scope models in this.props under names this.props.$KEY

Example:

import React from 'react'
import {subscribe, subLocal, subDoc, subQuery} from 'startupjs'

@subscribe(props => ({
  room: subDoc('rooms', props.roomId)
}))
export default class Room extends React.Component {
  updateName = () => {
    let {$store, $room} = this.props
    $room.set('name', 'New Name')
    // You can also use $store to do the same:
    $store.set('room.name', 'New Name')
  }
  render () {
    let {room} = this.props.store
    return <Fragment>
      <h1>{room.name}</h1>
      <button onClick={this.updateName}>Update Name</button>
    </Fragment>
  }
}

[Classes] sub*() functions

Use sub*() functions to define a particular subscription.

subDoc(collection, docId)

Subscribe to a particular document. You'll receive the document data as props.store.{key}

collection [String] -- collection name. Required docId [String] -- document id. Required

Example:

@subscribe(props => ({
  room: subDoc('rooms', props.roomId)
}))

subQuery(collection, query)

Subscribe to the Mongo query. You'll receive the docuents as an array: props.store.{key} You'll also receive an array of ids of those documents as props.store.{key}Ids

collection [String] -- collection name. Required query [Object] -- query (regular, $count, $aggregate queries are supported). Required

Example:

@subscribe(props => ({
  users: subQuery('users', { roomId: props.roomId, anonymous: false })
}))

IMPORTANT: The scope model ${key}, which you receive from subscription, targets an the array in the local model of the component, NOT the global collection path. So you won't be able to use it to efficiently update document's data. Instead you should manually create a scope model which targets a particular document, using the id:

let {usersInRoom, $store} = this.props.store
for (let user of usersInRoom) {
  $store.scope(`${collection}.${user.id}`).setEach({
    joinedRoom: true,
    updatedAt: Date.now()
  })
}

subLocal(path)

Subscribe to the data you already have in your local model by path. You'll receive the data on that path as props.store.{key}

You will usually use it to subscribe to private collections like _page or _session. This is very useful when you want to share the state between multiple components.

It's also possible to subscribe to the path from a public collection, for example when you want to work with some nested value of a particular document you have already subscribed to.

Example:

const TopBar = subscribe(props => ({
  sidebarOpened: subLocal('_page.Sidebar.opened')
}))({
  $sidebarOpened
}) =>
  <button
    onClick={() => $sidebarOpened.setDiff(true)}
  >Open Sidebar</button>

const Sidebar = subscribe(props => ({
  sidebarOpened: subLocal('_page.Sidebar.opened')
}))({
  store: {sidebarOpened}
}) =>
  sidebarOpened ? <p>Sidebar</p> : null

subValue(value)

A constant value to assign to the local scoped model of the component.

value [String] -- value to assign (any type)

[Classes] Example

Below is an example of a simple app with 2 components:

1. Home -- sets up my userId and renders Room
2. Room -- shows my user name ands lets user update it, shows all users which are currently in the room.

// Home.jsx
import React from 'react'
import Room from './Room.jsx'
import {model, subscribe, subLocal, subDoc, subQuery} from 'startupjs'

// `subscribe` means that the data is reactive and gets dynamically updated
// whenever the data in MongoDB or in private collections gets updated.

@subscribe(props => ({
  // Subscribe to the path in a private collection `_session`.
  //
  // `private` collection means that the data does NOT get synced with MongoDB.
  // Data in these collections live only on the client-side.
  //
  // Collection is considered `private` when its name starts from `_` or `$`.
  //
  // Private collections like `_session` are used as a singleton client-only storage,
  // an alternative to `Redux` or `MobX`.
  //
  // You can have as many private collections as you like, but the common
  // guideline is to use just one collection to store all private data -- `_session`
  userId: subLocal('_session.userId')
}))

export default class Home extends React.Component {
  constructor (...props) {
    super(...props)

    // For each thing you subscribe to, you receive a scoped `model`
    // with the same name prefixed with `$` in `props`. Use it
    // to update the data with the `model` operations available in Racer:
    // https://derbyjs.com/docs/derby-0.10/models
    let {$userId} = this.props

    // Update the private path `_session.userId` with the new value
    //
    // We'll use this `_session.userId` in all other children
    // components to easily get the userId without doing the potentially
    // heavy/long process of fetching the userId over and over again.
    $userId.set(this.getUserId())
  }

  // Get my userId somehow (for example from the server-side response).
  // For simplicity, we'll just generate a random guid in this example
  // by creating an empty user document each time, so whenever
  // you open a new page, you'll be a new user.
  getUserId = () => model.add('users', {})

  render = () => <Room roomId={'myCoolRoom1'} />
}

// Room.jsx
import React from 'react'
import {model, subscribe, subLocal, subDoc, subQuery} from 'startupjs'

@subscribe(props => ({

  // Subscribe to the same private path again to get the userId, which
  // we did manually setup in the parent `<Home>` component.
  // The pattern of subscribing and updating data in a private path
  // can be used to expose some data from one component to another.
  userId: subLocal('_session.userId'),

  // Subscribe to the particular document from a public collection `rooms` by id.
  // `public` means that it DOES sync with MongoDB.
  // `public` collection names start with a regular letter a-z.
  // You can also use ClassCase for collection names (A-Z), but it is
  // NOT recommended unless you have such guidelines in your project.
  room: subDoc('rooms', props.roomId)

}))

// All things you subscribe to end up in `props.store` under the same name.
// We can do a second subscribe using the data we received in the first one.

@subscribe(props => ({

  // Subscribe to the particular document from a public collection by id
  // which we got from the previous subscription
  myUser: subDoc('users', props.store.userId),

  // Subscribe to a query to get docs from a public `users` collection
  // using the array of userIds from `room` received in the previous subscription
  users: subQuery('users', {_id: {
    $in: props.store.room && props.store.room.userIds || []
  }})

}))

// Additionally, whenever you subscribe to the MongoDB query, you also
// receive the `Ids` in store.
// For example, subscribing to the `users` collection above populated
// `props.store.users` (array of documents) AND
// `props.store.userIds` (array of ids) - auto singular name with the `Ids` suffix

export default class Room extends React.Component {
  constructor (...props) {
    super(...props)
    let {$room, roomId} = this.props
    let {userId, room, room: {userIds = []}} = this.props.store

    // Create an empty room if it wasn't created yet
    if (!room) model.add('rooms', {id: roomId, title: `Room #${roomId}`})

    // Add user to the room unless he's already there
    if (!userIds.includes(userId)) $room.push('userIds', userId)
  }

  changeName = (event) => {
    let {$myUser} = this.props
    $myUser.setEach({name: event.target.value})
  }

  render () {
    let { myUser, room, users, userId } = this.props.store
    return (
      <main>
        <h1>{room.title}</h1>
        <section>
          My User Name:
          <input type='text' value={myUser.name} onChange={this.changeName} />
        </section>
        <h3>Users in the room:</h3>
        {
          users
          .filter(({id}) => id !== userId) // exclude my user
          .map(user =>
            <section key={user.id}>
              {user.name || `User ${user.id}`}
            </section>
          )
        }
      </main>
    )
  }
}

License

MIT

(c) Decision Mapper - http://decisionmapper.com