associate nested attributes with the ids they get after save

class Member < ActiveRecord::Base
  has_many :posts
  accepts_nested_attributes_for :posts
end

params = { :member => {
  :name => 'joe', :posts_attributes => [
    { :title => 'Kari, the awesome Ruby documentation browser!' },
    { :title => 'The egalitarian assumption of the modern citizen' },
  ]
}}

member = Member.create(params['member'])

After doing this I want is to map the elements in posts_attributes in params hash to th开发者_如何学编程e id's (The primary keys) after they are saved. Is there any thing I can do when accepts_nested_attributes_for builds or creates each record

PS: posts_attributes array may not contain index in sequence I mean this array might not contain index like 0,1,2 it can contain index like 0,127653,7863487 as I am dynamically creating form elements through javascript

also, I want is to associate only new records created in Post and not already existing Post

Thanks in Advance

---

Have you considered refreshing the posts association and grabbing the posts_attributes array in full?

Unfortunately, there is not a reliable way to do what you want. You could try looping over both and finding the IDs associated with the content using string matching, but without a field on the posts that is guaranteed to be a unique value, there's not an effective way to do it.

---

Although I'm not quite sure about what elements you want to assign with what ids, I think this approach would give you a hint.

You may assign a method name symbol to :reject_if, then put your logic into that method, like this:

class Member < ActiveRecord::Base
  has_many :posts
  accepts_nested_attributes_for :posts, :reject_if => :reject_posts?

  def reject_posts?(attrs)
    # You can do some assignment here
    return true if attrs["title"].blank?
    post_exist = self.posts.detect do |p|
      p.title == attrs["title"]
    end
    return post_exist
  end
end