Ember.js this in callback - ember.js

Question

I have an action in my controller to create a new page which is one of my models.
Afterwards, I want to clear out the form and transition to the new page.
Here is my code:
App.ApplicationController = Ember.ObjectController.extend
newSlug: (->
# some function
).property('newTitle')
newMenuName: # some property
actions:
addNewPage: ->
# Get the site
site = #get('model')
# Get all the pages associated with the site
pages = site.get('pages')
# ...
# snipped a bunch out to save space
# ...
# Create a new page passing in our title, slug and menu_name
page = pages.createRecord({title: title, slug: slug, menu_name: menu_name, menu_1: menu_1, menu_2: menu_2, menu_1_order: menu_1_order, menu_2_order: menu_2_order})
page.save().then(onSuccess, onError)
onSuccess = (page) ->
page = this.store.find('page', slug)
console.log('Slug: ' + slug + ' ' + page.slug)
#set('newTitle', '')
#set('newSlug', '')
#set('newMenuName', '')
$('#addPageModal').foundation('reveal', 'close')
#transitionToRoute('page', page)
But I'm getting the error that this has no method set. I have even tried using self = this but it gives me the same error.
Any thoughts?
BTW, in case you're wondering, inside onSuccess, page is not defined, so I have to look it up again. I thought a promise was supposed to return the data sent back from the API.
EDIT:
I must look like a total imbecile, but once again, right after posting a question here, I find (part) of the answer myself. Turns out in CoffeeScript (so far I'm not a big fan of it in combination with Ember.js) I needed the => so my callback function becomes:
onSuccess = (page) =>
page = this.store.find('page', slug)
console.log('Slug: ' + slug + ' ' + page.slug)
#set('newTitle', '')
#set('newSlug', '')
#set('newMenuName', '')
$('#addPageModal').foundation('reveal', 'close')
#transitionToRoute('page', page)
However, page is still not defined. Not sure what to do about that.
EDIT:
And the correct answer is....
App.ApplicationController = Ember.ObjectController.extend
newSlug: (->
# some function
).property('newTitle')
newMenuName: # some property
actions:
addNewPage: ->
# Get the site
site = #get('model')
# Get all the pages associated with the site
pages = site.get('pages')
# ...
# snipped a bunch out to save space
# ...
onSuccess = (page) ->
#set('newTitle', '')
#set('newSlug', '')
#set('newMenuName', '')
$('#addPageModal').foundation('reveal', 'close')
#transitionToRoute('page', page.get('slug'))
# And just for completeness
onError = (page) =>
# Do something
# Create a new page passing in our title, slug, menu_name, etc.
page = pages.createRecord({title: title, slug: slug, menu_name: menu_name, menu_1: menu_1, menu_2: menu_2, menu_1_order: menu_1_order, menu_2_order: menu_2_order})
page.save().then(onSuccess, onError)