how can we get only newly added object after update using accepts_nested_attributes_for assocation in rails

Question

My association looks like this :

class Abc < ApplicationRecord
  has_many :def
  accepts_nested_attributes_for :def, allow_destroy: true
end

class AbcController < ApplicationController

  def update
    abc = Abc.find(params[:id])
     if abc.update(abc_params)
       # TODO Here update is sucessful but  how to get all newly added def in database with their id?
     end
  end


  private
  def abc_params
    params.require(:abc).permit(def_attributes: [:name, :title,:wordcount, :id])
  end
end

We know accepts_nested attributes creates a new nested object in the database so how can I get all the newly added(not already existing) def object with their database id in AbcController update function ?

what activerecord object does this return? `abc.update(abc_params)`, use byebug and see.. — Md. Farhan Memon, May 10 '17 at 08:39
Just a tip - use `foo`, `bar` as placeholders. `def` is a keyword in Ruby and makes this example very confusing. — max, May 10 '17 at 11:28

score 0 · Answer 1 · answered May 10 '17 at 12:56

0

One solution is (not a direct one)..

def update
  abc = Abc.find(params[:id])
  number_of_defs = abc.defs.length
  if abc.update(abc_params)
    number_newly_added_defs = abc.defs.length - number_of_defs
    newly_added_defs = abc.defs.last(number_newly_added_defs)
  end
end

you will get the desired output.

answered May 10 '17 at 12:56

Naveen Krishnan

356
2
6

@ananta could you plese confirm on this?. or did you get any other better solution? – Naveen Krishnan May 26 '17 at 06:33

how can we get only newly added object after update using accepts_nested_attributes_for assocation in rails

1 Answers1