Rails How To Manually Create Child Object Without Form - ruby-on-rails-3

Question

I was wondering what the best implementation would be to programatically generate a single child object for a parent(s) without the use of a form.
In my case I have an existing forum system that I would like to tie into my Upload system via comments. I would like to manually create a child Forum object to discuss said upload in the same create action that the Upload is created. The two models have a relationship as so:
Child forum:
class Forum < ActiveRecord::Base
...
belongs_to :upload
end
Parent upload:
class Upload < ActiveRecord::Base
...
has_one :forum
end
I was thinking of something along the lines of:
class UploadsController < ApplicationController
...
def create
#Create the upload and a new forum + initial post to discuss the upload
#upload = Upload.new(params[:upload])
#forum = Forum.new(:upload_id => #upload.id, :title => #upload.name...)
#first_post = Post.new(:forum_id => #forum.id....)
if #upload.save && #topic.save && #first_post.save
redirect_to :action => "show", :id => #upload.id
else
redirect_to :action => "new"
end
end
end
Which is fairly close to what I wanted to do but the parent ids aren't generated until the parent objects are saved. I could probably do something like:
#upload.save
#forum = Forum.new(:upload_id => #upload.id...
#forum.save....
But I thought it might be cleaner to only persist the objects if they all validated. I'm not sure, does anybody else know of a better implementation?

Answer 1

I would recommend moving the forum creation from the controller to the model. The forum will only be created on the successful creation of the Upload.
class Upload < ActiveRecord::Base
...
has_one :forum
after_create :create_forum
...
def create_forum
Forum.create(:upload_id => self.id, :title => self.name...)
end
end
class Forum < ActiveRecord::Base
...
has_many :posts
after_create :create_first_post
...
def create_first_post
Post.new(:forum_id => self.id)
# or self.posts << Post.new()
end
end