Nested Models Creation

I am trying to build a nested model but I have a problem:

In new method in TopicController.rb

def new
  @topic = Topic.new
  @topic.message = Message.find(params[:id])
  @topic.build_comment
end

And now in create I have (1st try):

def create
  @cuser = current_facebook_user.fetch
  @topic = Topic.new(:topic)

  respond_to do |format|
    if @topic.save
      format.html { redirect_to(@topic, :notice => 'Topic was successfully created.') }
    else
      format.html { render :action => "new" }
    end
  end
en开发者_开发技巧d

Error for 1st try:

ActiveRecord::RecordNotFound (Couldn't find Message with ID=1 for Topic with ID=):

I also tried (2nd try):

def create
  @cuser = current_facebook_user.fetch
  @topic = Topic.new
  @topic.message = params['topic']['message_id'] #enters nil instead of the message_id
  @topic.comment = params['topic']['comment_id'] #enters nil instead of the comment_id
  @topic.user = User.find(1) #enters correct user_id

  respond_to do |format|
    if @topic.save
      format.html { redirect_to(@topic, :notice => 'Topic was successfully created.') }
    else
      format.html { render :action => "new" }
    end
  end
end

Error for second try:

No Error but Topic.message_id = nill and Topic.comment_id = nill. Those values are not assigned.

Any suggestions?

Thanks

If message and comment are defined as associations in the Topic model, you shouldn't assign IDs to them, but objects, like this:

@topic.message = Message.find(params[:topic][:message_id])
@topic.comment = Comment.find(params[:topic][:comment_id])

This only makes sense, of course, if both message and comment have already been created.