how to avoid saving empty records on a nested rails form

Question

I'm using the nested_form gem for my AddressBook relation. When the user blanks out the value of an existing Addr, I want to delete that Addr rather than saving with a blank value

class Person < ActiveRecord::Base   has_many :addrs, dependent: :destroy   attr_accessible :name, :addrs_attributes   accepts_nested_attributes_for :addrs, reject_if: :addr_blank, allow_destroy: true    def addr_blank(a)     valid? && a[:id].blank? && a[:value].blank?    end  class Addr < ActiveRecord::Base   belongs_to :person   attr_accessible :kind, :label, :value, :person_id 

My :reject_if method works well but it doesn't give me everything I need

1. valid? keeps my blank Addrs around through validation
2. a[:id].blank? avoids rejections when the user blanks out and existing record

Now, I need to delete (rather than save) an existing Addr when the user blanks the value. Also, I'm exposing Persons and Addrs via a RESTful API. I see two possible options:

1. Post process the params hash to add the magical _destroy=1 param. IOW, emulate the user activity of pressing the delete button.
2. Encapsulate this inside the Addr model such that an update with a blank value is effectively considered a delete.

Based on the advice here is how I implemented it:

people_controller.rb

def update   @person = Person.find(params[:id])   @person.destroy_blank_addrs(params[:person])   respond_to do |format|   ... 

person.rb

def destroy_blank_addrs(person_params)   if valid? && person_params[:addrs_attributes]     person_params[:addrs_attributes].each do |addr_params_array|       addr_params= addr_params_array[1]        addr_params[:_destroy] = '1' if !addr_params[:id].blank? && addr_params[:value].blank?      end   end end 

Answer 1

accepts_nested_attributes_for :addrs,    allow_destroy: true,    :reject_if => proc { |att| att[:name].blank? && attr[:description].blank? } 

Answer 2

accepts_nested_attributes_for :addrs,    allow_destroy: true,    reject_if: -> { |attr| [name, description].any? &:blank? }