How to save an object after submit with decent_exposure?

Question

I'm completely at a loss! I'm using decent_exposure gem for a first time and I suppose the problem is in it. That's the link https://github.com/hashrocket/decent_exposure When I submit my form, it saves nothing. All my table in database are just full of empty fields. This is my form

<%= simple_form_for book do |f| %>
    <%= f.input :name %>
    <%= f.input :author %>
    <%= f.input_field :annotation %>
    <%= f.button :submit %>
<% end %>

This is my controller:

class BooksController < ApplicationController
  before_filter :is_admin?
  before_filter :authenticate_user!
  expose(:book, finder_parameter: :id, params: :book_params)
  #I've tried both expose(:book) and expose(:books)

  def create
    if book.save
      redirect_to(book)
    else
      render :new
    end
  end

  def update
    if book.save
      redirect_to(book)
    else
      render :edit
    end
  end

  def show
  end

  def is_admin?
    if current_user.admin?
      true
    else
      render :text => 'Registrate'
    end
  end

  def book_params
    params.require(:book).permit(:name, :author, :annotation)
  end

end

It gives a mistake

param is missing or the value is empty: book

def book_params
    params.require(:book).permit(:name, :author, :anotation)
  end

If I try just expose(:book) without params and book_params method, it seems to be okay but after submitting the form all the fields are nil. What am I doing wrong? Is there any mistake in params defining? I've been thinking and trying different variants for many many times and I can't imagine where is the problem. Every help would be appreciated!

Answer 1

I found it! There was "attribures: :book_params" instead of "params: :book_params"

Answer 2

What happens if you change line 4 in your controller from

expose(:book, finder_parameter: :id, params: :book_params)

to

expose(:book, params: :book_params) ?