class Movie < ActiveRecord::Base
    has_many :genreships
    has_many :genres, through: :genreships

    accepts_nested_attributes_for :genres, :reject_if => :all_blank, :allow_destroy => true
    accepts_nested_attributes_for :genreships, :reject_if => :all_blank, :allow_destroy => true
end

class Genreship < ActiveRecord::Base
    belongs_to :movie
    belongs_to :genre

    accepts_nested_attributes_for :genre, :reject_if => :all_blank
end

class Genre < ActiveRecord::Base
    has_many :genreships
    has_many :movies, through: :genreships
end

= simple_form_for @movie do |f|
  .field
    = f.input :title
  .field
    = f.input :release_date, label: 'Release Date', order: [:month, :day, :year], start_year: 1901
  .field
    = f.input :summary, as: :text
  #genres
    = f.simple_fields_for :genreships do |genreship|
      = render 'genreship_fields', :f => genreship
    | #{link_to_add_association 'add a genre', f, :genreships} | #{link_to_add_association 'create a new genre', f, :genres}
  .actions = f.submit 'Save', class: 'btn btn-default'

.nested-fields
  #genre_from_list
    = f.association :genre, :collection => Genre.order(:name), :prompt => 'Choose an existing genre'
  = link_to_remove_association "remove genre", f

.nested-fields
  = f.input :name
  = link_to_remove_association "remove form", f