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startupjs racer-orm

ORM system for Racer.js and ShareDB

What it does

Lets you automatically override your scope models (created with .at() and .scope()) with the additional methods.

Usage

StartupJS project has the ORM plugin enabled by default, so you don't need to do any initialization and can just start adding new ORM entities.

If you are using this package standalone, you'll need to add the orm plugin manually:

import Racer from 'racer'
import racerOrm from '@startupjs/orm'
Racer.use(racerOrm)

Then start adding the ORM entities to your model. Each ORM Entity must be inherited from either:

  • Model.ChildModel from racer package.
  • or recommended BaseModel from startupjs/orm package. This one has additional helper methods like .getId and .getCollection and can also use ActionRecord-like associations.
import { Model } from 'racer'

class PlayerModel extends Model.ChildModel {
  alert (message) {
    this.set('alert', this.get('name') + ', ' + message)
    this.setDiff('showAlert', true)
  }
}

class GamesModel extends Model.ChildModel {
  async addNew (userId = 'system', params = {}) {
    let gameId = this.id()
    await this.add('games', {
      name: 'Dummy Game',
      ...params,
      id: gameId,
      userId,
      playerIds: [],
      createdAt: Date.now()
    })
    return gameId
  }
}

class GameModel extends Model.ChildModel {
  async alertPlayers (message) {
    let playerIds = this.get('playerIds')
    let playersQuery = this.root.query('players', { _id: { $in: playerIds } })
    await this.subscribe(playersQuery)
    for (let playerId of playersQuery.getIds()) {
      this.scope('players.' + playerId).alert(message)
    }
  }

  async addPlayer (userId, params = {}) {
    if (!userId) throw new Error('userId required')
    var playerId = this.id()
    await this.root.add('players', {
      ...params,
      id: playerId,
      userId,
      createdAt: Date.now()
    })
    await this.push('playerIds', playerId)
    return playerId
  }
}

racer.orm('games', GamesModel)
racer.orm('games.*', GameModel)
racer.orm('players.*', PlayerModel)

// ...

async function main ($root) {
  let $games = $root.scope('games')
  let gameId = await $games.addNew('userId1', { name: 'Cool game' })
  let $game = $games.at(gameId)
  for (let userIds of ['userId1', 'userId2', 'userId3']) {
    await $game.addPlayer(userIds)
  }
  $game.alertPlayers('please join the game!')
}

// ...

Factory

Sometimes you want to dynamically decide which ORM to use based on the document's data. Factory let you do that.

Example:

class BasePlayerModel extends Model.ChildModel {
  getColor () {
    throw new Error('Player color is unknown')
  }
}

class AlliedPlayerModel extends BasePlayerModel {
  getColor () {
    return 'blue'
  }
}

class RivalPlayerModel extends BasePlayerModel {
  getColor () {
    return 'red'
  }
}

function PlayerFactory ($player, $parent) {
  // $player here is going to be just a pure scoped model
  let playerTeamId = $player.get('teamId')
  let $root = $player.root
  let myTeamId = $root.get('_session.myTeamId')

  // you have to always pass `$parent` when manually
  // instantiating the ORM Entity
  if (!playerTeamId || !myTeamId) return new BasePlayerModel($parent)

  if (playerTeamId === myTeamId) {
    return new AlliedPlayerModel($parent)
  } else {
    return new RivalPlayerModel($parent)
  }
}
PlayerFactory.factory = true

racer.orm('players.*', PlayerFactory)

Alias

You can optionally specify an alias for the ORM Entity:

racer.orm('players.*', PlayerModel, 'Player')

This will allow you to explicitly specify in .at() and .scope() which ORM Entity to use even for the unknown path patters:

let playerId = 'playerId1'
// will create the PlayerModel, since it matches the specified path pattern:
model.scope('players.' + playerId).alert('please join the game!')

// The following will also create the PlayerModel
// even though '_session.myPlayer' wasn't specified in the orm path patterns:
model.scope('_session.myPlayer', 'Player').alert('please join the game!')

IMPORTANT: Note, that this is a bad practice and must only be used in the edge cases.

It's always better to list all your path patterns explicitly and don't use aliases at all:

racer.orm('players.*', PlayerModel)
racer.orm('_session.myPlayer', PlayerModel)
racer.orm('_session.rivalPlayer', PlayerModel)

JSON Schema validation of documents.

Associations decorators

Association allow you to describe relationships between ORM entities for reuse in your code.

belongsTo(AssociatedOrmEntity, options)

Specifies a one-to-one association with another ORM entity. This decorator should only be used if this ORM entity contains the foreign key.

AssociatedOrmEntity (OrmEntityClass): associated orm entity

options (Object):

  • key: foreign key name (default: collection + 'Id')
  • any other custom properties

hasOne(AssociatedOrmEntity, options)

Specifies a one-to-one association with another ORM entity. This decorator should only be used if the other ORM entity contains the foreign key.

AssociatedOrmEntity (OrmEntityClass): associated orm entity

options (Object):

  • key: foreign key name (default: collection + 'Id')
  • any other custom properties

hasMany(AssociatedOrmEntity, options)

Is similar to hasOne, but indicates a one-to-many association with another ORM entity.

AssociatedOrmEntity (OrmEntityClass): associated orm entity

options (Object):

  • key: foreign key name (default: collection + 'Ids')
  • any other custom properties
import { BaseModel, hasMany } from 'startupjs/orm'
import GamesModel from './GamesModel'
import GameModel from './GameModel'
import PlayerModel from './PlayerModel'

racer.orm('games', GamesModel)
racer.orm('games.*', hasMany(PlayerModel)(GameModel))
racer.orm('players.*', PlayerModel)

Installation

  1. in server/index.js add validateSchema: true to startupjsServer() options
  2. Go to one of your ORM document entities (for example, UserModel, which targets users.*) and add a static method schema:
import { BaseModel } from 'startupjs/orm'

export default class UserModel extends BaseModel {
  static schema = {
    firstName: { type: 'string' },
    lastName: { type: 'string' },
    age: {
      type: 'number',
      multipleOf: 1,
      minimum: 0,
      maximum: 130
    }
  }
}

Notes

  1. Schema is checked on both client-side and server-side.
  2. Schema validation only works in development. So there won't be any performance overheads when NODE_ENV is production
  3. Only ORMs targeting documents path <collection>.* are gonna be parsed for schema definitions.

Licence

MIT

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