ActiveRecord::AssociationTypeMismatch when attempting to save nested attributes in Rails

Question

I read through a lot of pages on `has_one relationships and nested attributes but haven't been successful in making this work. Any help would be fantastic.

Each User has_one Network. I'm trying to gather information for both attributes in one form but keep getting the exception ActiveRecord::AssociationTypeMismatch in UsersController#create

The parameters passed are:

{"utf8"=>"✓",
 "authenticity_token"=>"I54tm1ovzHEHaXbBLTT+5tqBJv2795sKg978ot3HDBc=",
 "user"=>{"name"=>"Bilbo Baggins",
 "email"=>"bilbo@lotr.com",
 "password"=>"[FILTERED]",
 "password_confirmation"=>"[FILTERED]",
 "network"=>{"home_lng"=>"-87.91894912719727",
 "home_lat"=>"43.03812464542969",
 "center_lng"=>"-87.91894912719727",
 "center_lat"=>"43.03812464542969",
 "radius"=>"500"}},
 "commit"=>"Sign up"}

I'm guessing the parameters for Network have to somehow show up as network_attributes but I'm not sure how.

Controller:

def create
    @user = User.new(params[:user])
    if (@user.save)
      sign_in @user
      flash[:success] = "One ring to rule them all!"
      redirect_to @user
    else
      @title = "The journey begins..."
      render 'new'
    end
end

View:

<%= f.label :name %>
<%= f.text_field :name %>
<%= f.label :email %>
<%= f.text_field :email %><br />
<%= f.label :password %>
<%= f.password_field :password %>
<%= f.label :password_confirmation, "Confirmation" %>
<%= f.password_field :password_confirmation %>
  <%= f.fields_for @network do |fn| %>
    <%= fn.hidden_field :home_lng %>
    <%= fn.hidden_field :home_lat %>
    <%= fn.hidden_field :center_lng %>
    <%= fn.hidden_field :center_lat %>
    <%= fn.hidden_field :radius %>
  <% end %>

and of course, the Models:

class User < ActiveRecord::Base
  attr_accessor :password
  attr_accessible :name, :email, :password, :password_confirmation, :network_attributes, :network
  has_one  :network, :foreign_key => "user_id",
                     :dependent => :destroy

  accepts_nested_attributes_for :network,
                            :reject_if => :all_blank,
                            :allow_destroy => true
end

class Network < ActiveRecord::Base
  attr_accessible :home_lng, :home_lat, :center_lng, :center_lat, :radius
  belongs_to :user
end

Thank you

Answer 1

Incase someone else is having the same issue, I resolved this by changing:

<%= f.fields_for @network do |fn| %> to <%= f.fields_for :network do |fn| %> and removing :network as an accessible attribute from the user model.

Answer 2

Not certain, think you need:

<%= f.fields_for @network, :network_attributes do |fn| %>

Answer 3

If you remove :network from the model as an accessible it will not work for sure