title: ember-data: How to make a Saving/Saved flash message
body: <p>In order to make a little yellow "Saving"/"Saved" indicator message at the top of my app, I'd like to have a boolean property indicating if any ember-data records are currently in flight.</p>
  
  <p>I tried this:</p>
  
  <pre><code>App.store = DS.Store.create
    isSaving: (-&gt;
      for record in this.get('recordCache')
        if record?.getPath('stateManager.currentState.name') == 'inFlight'
          return true
      return false
    ).property('recordCache.@each.stateManager.currentState.name')
  </code></pre>
  
  <p>but then I discovered that <code>recordCache</code> is not observable.</p>
  
  <p>I don't use transactions, only <code>App.store.commit()</code>, so I looked at <code>App.store.get('defaultTransaction')</code>, but it didn't yield anything useful.</p>
  
  <p>I'm using the RESTAdapter, so if I can extend it into giving me this piece of information, that would work too.</p>