Rails nested form on HABTM: how to prevent duplicate entry?

Question

I have simple app with 3 tables in DB and \'many-to-many\' relationships.

# Model Employee
class Employee < ActiveRecord::Base
   has_and_belongs_to_many          


        

Answer 1

You can use rails validation to check uniqueness of record.

In your model phonenumber.rb put following line,

validates_uniqueness_of :column_name

It will ensure that Phonenumber will have unique phone_numbers only.

Now in controller you can check phone_number from params and if number is already exist then we will delete nested attributes fron params so that Phonenumber record wont generate.

 def create
   @phone_number = Phonenumber.where(:number=>params[:employee][:phonenumber][:number])
   if @phone_number.any?
      params[:employee].delete(:phonenumber)
      @employee = Employee.new(params[:employee])
      if @employee.save?
        @employee.phonenumber = @phone_number.first
        redirect_to :action => :index
      else
        render "new"
      end
   else
     @employee = Employee.new(params[:employee])
     @employee.save ? (redirect_to :action => :index) : (render "new")
   end
 end

Answer 2

in employee.rb:

before_save :get_phonenumbers


  def get_phonenumbers
    self.phonenumbers = self.phonenumbers.collect do |phonenumber|
      Phonenumber.find_or_create_by_number(phonenumber.number)
    end
  end

I have found its working