Missing belongsTo relationship

book.js.coffee

#Library.Book.url = '/books'
#Library.Book.adapter = Library.RESTAdapter.create()

attr = DS.attr
hasMany = DS.hasMany

Library.Book = DS.Model.extend
  code: attr()
  volume: attr()
  stock: attr('number')
  title: attr()
  subtitle: attr()
  adult: attr('boolean')
  notes: attr()
  author: attr()
  created_at: attr('date')

  checkouts: hasMany('checkout')

  available: (->
    copies_out = @get('checkouts').filterProperty('status', 'out').get('length')
    @get('stock') - copies_out
  ).property('stock', 'checkouts.@each.status')

  notAvailable: (->
    not @get('available')
  ).property('available')

  full_title: (->
    volume = @get('volume')
    title = @get('title')

    if volume
      @get('title') + ", vol. " + volume
    else
      @get('title')

  ).property('title', 'volume')

  match_filter: (filter)->
    filter = filter.toLowerCase()
    full_title = @get('full_title').toLowerCase()

    if full_title.indexOf(filter) < 0
      return false

    true

  noStock: (->
    if @get('stock') <= 0 then return true else return false
  ).property('stock')

Library.Book.reopenClass
  findByCode: (code) ->
    @find('code:' + code)

  cloneVolumeFrom: (item) ->
    if parseInt(item.get('volume'))
      next_volume = parseInt(item.get('volume')) + 1
    else
      next_volume = undefined

    cloned_book_params = {
      title: item.get('title')
      notes: item.get('notes')
      adult: item.get('adult')
      volume: next_volume
    }

    return cloned_book_params

checkout.js.coffee

attr = DS.attr
belongsTo = DS.belongsTo

Library.Checkout = DS.Model.extend
  book: belongsTo('book')
  patron: belongsTo('patron')
  status: attr()
  closed_at: attr('date')
  created_at: attr('date')

  isFullyLoaded: (->
    if @get('book.isLoaded') and @get('patron.isLoaded')
      return true

    return false
  ).property('book.isLoaded', 'patron.isLoaded')

  isOpen: (->
    if @get('status') == "out" then true else false
  ).property('status')

  duration: (->
    if @get('created_at') and @get('closed_at')
      diff = moment.duration(moment(@get('closed_at')).valueOf() - moment(@get('created_at')).valueOf())
      dur =  moment.duration(diff)
      return dur
    else if @get('created_at')
      diff = moment.duration(moment().valueOf() - moment(@get('created_at')).valueOf())
      dur =  moment.duration(diff)
      return dur
    else
      return null
  ).property('created_at', 'closed_at')

Library.Checkout.reopenClass
  findByInfo: (book_info, patron_info) ->
    @find('book_info:' + book_info)

JSON Response

{"checkouts":[{"id":223,"status":"out","created_at":"2013-10-20T17:05:15Z","closed_at":null,"book_id":25748,"patron_id":1149},{"id":224,"status":"out","created_at":"2013-10-20T17:05:15Z","closed_at":null,"book_id":25798,"patron_id":1179},{"id":225,"status":"out","created_at":"2013-10-20T17:05:15Z","closed_at":null,"book_id":25725,"patron_id":1150},{"id":226,"status":"out","created_at":"2013-10-20T17:05:15Z","closed_at":null,"book_id":25735,"patron_id":1208},{"id":227,"status":"out","created_at":"2013-10-20T17:05:15Z","closed_at":null,"book_id":25789,"patron_id":1135},{"id":228,"status":"out","created_at":"2013-10-20T17:05:15Z","closed_at":null,"book_id":25753,"patron_id":1138},{"id":229,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25788,"patron_id":1197},{"id":230,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25814,"patron_id":1154},{"id":231,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25802,"patron_id":1185},{"id":232,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25720,"patron_id":1143},{"id":233,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25737,"patron_id":1213},{"id":234,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25788,"patron_id":1160},{"id":235,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25804,"patron_id":1180},{"id":236,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25797,"patron_id":1222},{"id":237,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25758,"patron_id":1225},{"id":238,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25719,"patron_id":1159},{"id":239,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25809,"patron_id":1156},{"id":240,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25738,"patron_id":1199},{"id":241,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25785,"patron_id":1133},{"id":242,"status":"out","created_at":"2013-10-20T17:05:16Z","closed_at":null,"book_id":25766,"patron_id":1201}]}

patron.js.coffee

attr = DS.attr
hasMany = DS.hasMany

Library.Patron = DS.Model.extend
  code: attr()
  name: attr()
  gender: attr()
  email: attr()
  notes: attr()
  adult: attr()
  keepCheckoutHistory: attr()

  checkouts: DS.hasMany('checkout')

  match_filter: (filter)->
    filter = filter.toLowerCase()
    name = @get('name').toLowerCase()

    if name.indexOf(filter) < 0
      return false

    true

Library.Patron.camelizeKeys = true

Library.Patron.reopenClass
  findByCode: (code) ->
    @find('code:' + code)

#Library.Patron.url = '/patrons'
#Library.Patron.adapter = Library.RESTAdapter.create()