Remove association instead of destroying object when: allow_destroy => true

When using new accepts_nested_attributes_for

in ActiveRecord, the option can be used :allow_destroy => true

. When this option is set, any hash that contains nested attributes, such as {"_delete"=>"1", "id"=>"..."}

passed in update_attributes

, removes the nested object.

Easy setup:

class Forum < ActiveRecord::Base
  has_many :users
  accepts_nested_attributes_for :users, :allow_destroy => true
end

class User < ActiveRecord::Base
  belongs_to :forum
end

Forum.first.update_attributes("users_attributes"=>{"0"=>{"_delete"=>"1", "id"=>"42"}})
      

        
        
        
      

    

Question: How do I - instead of removing nested objects, when "_delete" => "1"

- just remove the association? (i.e. in the above case, set the forum_id for the user to nil)

Bonus question: What if I also want to change the attribute for the nested object when removing the association? (for example, to set a state or timestamp)