How to correctly style the Create method and save objects in the database?

Question

Ruby on Rails

There is a book, in each book there are pages, there are illustrations in the page. The connection is appropriate.
When creating new illustrations on a page, only the page id is stored in the database.
How can I save also the id of the book?

def create
  @book = Book.friendly.find(params[:book_id])
  @page = @book.pages.friendly.find(params[:page_id])
  @picture = @page.images.new(image_params)
  if @picture.save
    ...
  end
end

private
def image_params
  params.require(:picture).permit(:book_id, :picture)
end

I use gem 'friendly_id'

Answer 1

Does picture have a book_id field?
@picture.book = Does @book fire?
Update: Ah, well, it looks like the problem is that you have a string :book_id, and you need to write an integer in the field. Alternatively, you can find a book in the image_params method and add it to the parameters. I don't know if this is a good practice.