title: "Couldn't find" Error ActiveRecord.new method
body: <p>I facing this problem in may Rails 3.0.3 App, I think this is a silly error but I can't figure out why it's happening, or in fact, I'm misunderstanding the ActiveRecord behavior and it's is not really a error.</p>
  
  <p>This is the scenario, I've three models:</p>
  
  <pre><code>
  class User &lt; ActiveRecord::Base  
      devise :database_authenticatable, :registerable,
      :recoverable, :rememberable, :trackable, :validatable  
      has_many :addresses, :as => :addressable  
      accepts_nested_attributes_for :addresses  
  end
  
  class Address &lt; ActiveRecord::Base  
    belongs_to :addressable, :polymorphic => true  
    belongs_to :address_base  
    accepts_nested_attributes_for :address_base  
  end  
  
  class AddressBase &lt; ActiveRecord::Base  
    has_many :address  
  end
  </code></pre>
  
  <p>If I try to instantiate a new User passing a hash parameters, by this way: </p>
  
  <pre><code>
  User.new({"addresses_attributes"=>  
      {"0"=>
          {"number"=>"10",
           "complement"=>"Next Starbucks",
           "address_base_attributes"=>
              {"city"=>"San Francisco",
               "zip_code"=>"00010",
               "district"=>"San Francisco",
               "id"=>"10",
               "street"=>"Market St.",
               "state"=>"CA"}
          }
      },
      "name"=>"Homer Simpson",
      "password_confirmation"=>"[FILTERED]",
      "document"=>"123321111",
      "password"=>"[FILTERED]",
      "email"=>"homer@simpson.com"
  })
  </code></pre>
  
  <p>I face the error</p>
  
  <pre>Couldn't find AddressBase with ID=10 for Address with ID=</pre>
  
  <p>And it happens because that AddressBase already exists and the Address don't, if I remove the AddressBase.id parameter of the hash everything works, but I not want it, because on this way, always will be created a new register for Address and AddressBase. My intention is reuse commons AddressBase's, so the scenario of a new Address with an existent AddressBase will be necessary.</p>
  
  <p>Now this is my doubts, I'm missing some parameter in the AddressBase hash?? Something like saying that the record already exist? Or it's a problem with belongs_to and has_many associations of ActiveRecord?</p>
  
  <p>Thanks in advance.</p>