Nested attributes and params.require error

I am new to ruby on rails espacially nestes forms. I am trying to create an author and a book in the same form knowing that there's a many to many relationshio between them my code is presented below. book.rb

class Book < ActiveRecord::Base
has_many :exemplaires
has_many :talks, inverse_of: :book
has_many :subjects, through: :writings
has_many :writings
has_many :authors, through: :talks
accepts_nested_attributes_for :authors
validates :title, presence: true

end

author.rb:

class Author < ActiveRecord::Base
 has_many :talks
 has_many :books, through: :talks
end

talk.rb

class Talk < ActiveRecord::Base
 belongs_to :book
 belongs_to :author
end

book_controller.rb

class BooksController < ApplicationController

  def index

 end
 def list
   @books= Book.all
 end
 def new
   @book = Book.new
   @[email protected]
 end
 def create
    @book= Book.new(book_params)
    if @book.save
     flash[:notice]='goood'
     redirect_to admin_manage_path
    else
     flash[:alert]='ouups'
     redirect_to root_url
    end
  end



  private

  def book_params
   params.require(:book).permit(:title, :pages, :resume, :authors_attributes)
  end
  end

books\new.html.erb

<h1>Add new book</h1>
  <%= form_for(@book) do |form| %>
     <%= form.label :title %>
     <%= form.text_field :title %>
     <%= form.fields_for :authors do |tag_form| %>

       <%= tag_form.label :f_name %>
       <%= tag_form.text_field :f_name %>
    <% end %>

   <%= form.submit "Submit" %>
 <% end %>

what i got as error

Processing by BooksController#create as HTML Parameters: {"utf8"=>"✓", "authenticity_token"=>"qpGng8tOiC/B5VX2tphuhAe+Wq1vx7it1vEO6XmwZmI=", "book"=>{"title"=>"booooooooooooook", "authors_attributes"=>{"0"=>{"f_name"=>"auuuuuuuuuuuuuuuuuthor"}}}, "commit"=>"Submit"} Unpermitted parameters: authors_attributes

Solution

You need to whitelist the authors_attributes fields too:

  def book_params
   params.require(:book).permit(:title, :pages, :resume, authors_attributes: [:f_name])
  end