Rails can't save a nested resource via ActiveResource

Question

I'm having a problem using ActiveResource to save a model with a nested resource: I can load and save a non-nested resource with no problems, and I can load a resource plus its nested resources fine, but saving the resource fails. This problem occurs for me with REE 1.8.7/Rails 2.3.9 and Ruby 1.9.2-p0/Rails 3.0.2. The examples below are from Rails 3/AR 3. There are two models in my sample app: - Asset - Interface Assets have many Interfaces, Interfaces belong to Assets. routes.rb ``` Rails3Testapp::Application.routes.draw do resources :interfaces resources :assets end ``` Relevant AssetController actions ``` def index @assets = Asset.all respond_to do |format| format.html # index.html.erb format.xml { render :xml => @assets, :include => [ :interfaces ] } end end def show @asset = Asset.find(params[:id]) respond_to do |format| format.html # show.html.erb format.xml { render :xml => @asset, :include => [ :interfaces ] } end end def update @asset = Asset.find(params[:id]) respond_to do |…

Accepted Answer

ActiveResource doesn't have association support out of the box. interesting idea to hijack the nested_* stuff for this. This seems to work for me:

```
class Asset < ActiveRecord::Base
  has_many :interfaces
  accepts_nested_attributes_for :interfaces
  alias interfaces_attributes interfaces

def to_xml(options = {})
    super(options.merge({:methods => :interfaces_attributes}))
  end
end
```

move the to_xml options into the controller if you like. might want to also make sure Interface has the right attr_protected's.

Rails can't save a nested resource via ActiveResource

Solution

Problem