Firebase orm

firebase-orm.coffee

###*
@see http://bish.nu/2014/exposing-firebase-as-ORM-in-nodejs/
###
Firebase = require("firebase")
_ = require("underscore")

###*
Initialize the db (acting as ORM):

orm = require('./firebase-orm')

db = orm('http://myblog.firebaseio.com',
  process.env.FIREBASE_AUTH, [ 'posts', 'comments' ])

@param fbPath
@param auth
@param types
@returns {{data: {}}}
###
module.exports = (fbPath, auth, types) ->

  fbRoot = new Firebase(fbPath)
  db = data: {}
  data = db.data
  fbRoot.authWithCustomToken auth, (err, a) ->
    throw err if err

  types.forEach (type) ->
    data[type] = {}
    data[type].values = []
    data[type].ids = []
    data[type].cloud = fbRoot.child(type)
    data[type].cloud.on "child_added", (snap) ->
      remoteItem = snap.val()
      stringified = JSON.stringify(remoteItem)
      localIndex = data[type].values.length
      data[type].values[localIndex] = remoteItem
      data[type].ids[localIndex] = snap.name()
      return

    data[type].cloud.on "child_removed", (snap) ->
      remoteItem = snap.val()
      stringified = JSON.stringify(remoteItem)
      localIds = data[type].ids
      localItemIndex = localIds.indexOf(snap.name())
      if ~localItemIndex
        data[type].values.splice localItemIndex, 1
        localIds.splice localItemIndex, 1
      return

    data[type].cloud.on "child_changed", (snap) ->
      remoteItem = snap.val()
      stringified = JSON.stringify(remoteItem)
      localIds = data[type].ids
      localItemIndex = localIds.indexOf(snap.name())
      data[type].values[localItemIndex] = remoteItem  if ~localItemIndex
      return

    return

  ###

  Use db.read to read back the full list of objects of a particular resource type:

  db.read 'posts', (e, posts) ->
    console.log(posts)

  @param type
  @param fn

  ###
  db.read = (type, fn) ->
    values = data[type].values
    fn null, values.map((obj, i) ->
      id = data[type].ids[i]
      _.extend _.clone(obj),
        id: id

    )
    return

  ###

  Use db.create to create new objects of provided resource type:

  db.create 'posts',
    title: 'Title',
    body: 'Body'
  , (e, post) ->
    id = post.id
    console.log('created with id', id)

  @param type
  @param obj
  @param fn

  ###
  db.create = (type, obj, fn) ->
    ref = data[type].cloud.push(obj, (e) ->
      return fn(e)  if e
      fn null, _.extend(_.clone(obj),
        id: ref.name()
      )
      return
    )
    return

  ###

  Use db.update to update a particular object:

  db.update 'posts', post.id,
    title: 'New title'
  , (e, post) ->
    console.log('updated', post)


  @param type
  @param id
  @param attributes
  @param fn
  @returns {*}

  ###
  db.update = (type, id, attributes, fn) ->
    info = getResource(data[type], id)
    ref = info.ref
    obj = info.obj
    return fn(new Error("Resource not found in database"))  unless obj
    _.extend obj, _.omit(attributes, "id")
    ref.set obj, (e) ->
      return fn(e)  if e
      fn null, _.extend(_.clone(obj),
        id: id
      )
      return

    return

  ###

  Use db.delete to delete a particular object from database:

  db.delete 'posts', id, (e, post) ->
    console.log('deleted', post)

  @param type
  @param id
  @param fn
  @returns {*}

  ###
  db.delete = (type, id, fn) ->
    info = getResource(data[type], id)
    ref = info.ref
    obj = info.obj
    return fn(new Error("Resource not found in database"))  unless obj
    ref.remove (e) ->
      return fn(e)  if e
      fn null, _.extend(_.clone(obj),
        id: id
      )
      return

    return

  getResource = (dataObj, id) ->
    index = dataObj.ids.indexOf(id)
    obj = dataObj.values[index]
    return {}  unless obj
    ref: dataObj.cloud.child(id)
    obj: obj

  return db