On Apr 23, 4:34 ¨Βν¬ ΝαξοΛυναΌναξοκσ®ξ®®®ΐηναιμ®γονχςοτεΊ
> What is the difference between
>
> parent.children << child.new
>
> and
>
> parent.children.build(params[:child])

http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html

Under has_many examples, build is used to automatically fill up the
relationship data. The documentation is your friend, spend some time
reading it.

Now that I've google that for you, another useful link:

http://rubyonrails.org/community

Post your Ruby on Rails related questions there in the Rails mailing
lists, not here as there are better chances you don't get any answer
at all since this list is mainly Ruby.

--
Luis Lavena