In Ember pushObject calls supposed callbacks but removeObject does not

Question

I got the following WorkSpec item controller, which controls checkboxes state:

ContractorApp.WorkSpecController = Em.ObjectController.extend
  needs: ['account']
  selected: (->
    work_spec = @get 'content'
    work_specializations = @get 'controllers.account.work_specializations'
    work_specializations.contains work_spec
    ).property()

  selection_changed: (->
    work_spec = @get 'content'
    work_specializations = @get 'controllers.account.work_specializations'

    limit = @get 'controllers.account.specialization_limit'

    if @get( 'selected' ) && work_specializations.get('length') < limit
      work_specializations.pushObject work_spec
    else
      work_specializations.removeObject work_spec
    ).observes('selected')

As you see work_specializations is the parent's set of work specializations: I want to control (work_specializations.get('length') < limit) the addition of an element to the array.

The problem here that I got observer in the model contained the work_specializations array:

ContractorApp.ContractorProfile = DS.Model.extend
  work_specializations: DS.hasMany "work_specialization"
  on_spec_change: ( ->
    ws_ids = @get( 'work_specializations').map (ws)->
      ws.get 'id'
    @set( 'work_specialization_ids', ws_ids )
  ).observes 'work_specializations'

For some reason the call of 'work_specializations.pushObject work_spec' calls the model's callback but its counterpart removeObject does not. Any ideas why?

Answer 1

You're observing the collection itself, not items being added or removed. It's likely that the first change is triggering the observes to fire for the first time.

on_spec_change: ( ->
  ws_ids = @get( 'work_specializations').map (ws)->
    ws.get 'id'
  @set( 'work_specialization_ids', ws_ids )
).observes 'work_specializations.[]'