Q:

Ember.js with Rails accepts_nested_attributes_for and polymorphic has_many/belongs_to

On the Rails API side I have the following 2 models:
class Grower < ActiveRecord::Base
 has_many :addresses, as: :addressable
 accepts_nested_attributes_for :addresses
end

class Address < ActiveRecord::Base
  belongs_to :addressable, polymorphic: true
end

as well as a Growers controller which returns and can create/update Growers with embedded Addresses attributes.  I also have an Addresses controller with proper routing so that Addresses can be viewed/created/updated for a specific Grower.  The latter is more of an "in-case", and I'm not sure I'll be needing to return/update/create addresses as a separate payload. 
I am starting to try and piece together an Ember app that would allow me to view/edit/create a Grower at the same time as its Address(es).  Can anyone point me to an existing real or sample app that does this?  I will be posting my code as I go along, but I already have an idea of some areas where I will be running into trouble:

Rails returns/expects nested params named addresses_attributes.  Ember, I am sure, doesn't use that convention.  What's the best approach of resolving this? 
Because of the polymorphic association (objects other than Grower can be addressable), on the API/Address side, to get the correct belongs_to object, Rails uses addressable_id in conjunction with addressable_type.  In this example the addressable_type would be "Grower", and the addressable_id would be the grower_id value.  How would one go about translating that on the Ember side? 

UPDATE:
I got it to work at least a couple different ways.  My preferred solution, at least for this particular case, is in the answer section. 

A:

Here is a sample of code based @yuяi's strategy that worked well for me:
App. Post = DS.Model.extend
    comments: DS.hasMany('comment')

App. PostSerializer = DS.ActiveModelSerializer.extend( DS.EmbeddedRecordsMixin,
    attrs:
        comments: {embedded: 'always'}

    keyForAttribute: (attr) ->
        if attr == "comments"
            "comments_attributes"
        else
            @_super(attr)
)

This solution worked well with Ember 1.6.1 and Ember Data 1.0.0-beta.8.2a68c63a. 

A:

I found a couple ways to get it done, but the final approach doesn't require any changes on the Rails/API side. 
On the client (Ember) side:

I added the addresses hasMany property to the App. Grower model.  I also mapped it on the RESTAdapter to what's expected from the API, by setting the key for addresses to addresses_attributes. 
I added the grower (for now - will change to addressable once I have other addressable models) belongsTo property on App. Address.  It's not really required for what I'm doing, but it might be useful in the future. 
I set the addresses on the RESTAdapter to be embedded: 'always'. 
On the App. GrowersEditController, I just do a model.save (transaction.commit), and the child addresses are automatically saved via the API call. 
On the App. GrowersAddController, I use the App. Address.createRecord and App. Grower.createRecord methods using the user-entered Grower and Address data.  Then I use the pushObject method to append the Address to the Grower, and then call a save on the Grower (commit on transaction).  Again, the address data gets submitted and saved automatically.