Nested Attributes not Working in Form

I have a form that uses two models - badge and badge winners. The user_id and community_id fields are needed for badge_winners which is nested in badges. I was trying to learn from Ryan Bates’ Railscast (http://railscasts.com/episodes/196-nested-model-form-part-1)

The error I’m getting is:

ActiveRecord::UnknownAttributeError in BadgesController#create

unknown attribute: user_id

app/controllers/badges_controller.rb:42:in `new’

LIne 42 corresponds to this line in :create

@badge = Badge.new(params[:badge])

here’s the controller:

def new

@badge = Badge.new

badge_winner = @badge.badge_winners.build

respond_with(@badge)

end

def create

@badge = Badge.new(params[:badge])

if @badge.save

flash[:notice] = “Badge was successfully created.”

redirect_to home_path

else

flash[:notice] = “There was a problem creating your badge.”

redirect_to home_path

end

end

Here’s the form (both community_id and user_id are populating fine):

<%= form_for(@badge) do |f| %>

<%= f.label :Description %>

<%= f.text_area :description %>

<%= f.fields_for :badge_winners do |builder| %>

<%= builder.hidden_field :user_id ,:value => user_id %>

<%= builder.hidden_field :community_id ,:value => community_id %>

<% end %>

<%= f.submit “Give Badge” %>

<% end %>

The models (user_id and community_id are fields in the BadgeWinner table):

class Badge < ActiveRecord::Base

belongs_to :community

has_many :badge_winners, :dependent=>:destroy

accepts_nested_attributes_for :badge_winners

end

class BadgeWinner < ActiveRecord::Base

belongs_to :user

belongs_to :badge

end

I’m hoping someone’s able to help. I just know it’s a newbie error somewhere. Thanks in advance for any assistance!