Why do I get the error `undefined method 'map'`? - ruby-on-rails

Question

In my Ruby on Rails application I am trying to display a three drop down menus in the _form.html.erb which are rendered from the file _booking_lookup.html.erb and get there data from the drop down menu methods in the models.
_form.html.erb:
<%= render(:partial => '/booking_lookup', :locals=> {:film => #film = Film.all, :showings => #showings = Showing.all, :seats => #seats = Seat.all, :my_path => '/films/booking_lookup' }) %>
_booking_lookup.html.erb:
<%= form_tag my_path, :method=>'post', :multipart => true do %>
<%= select_tag ('title_id'),
options_from_collection_for_select(#films, :id, :title_info, 0 ),
:prompt => "Film" %>
<%= select_tag ('showings_id'),
options_from_collection_for_select(#showings, :id, :showing_times, 0 ),
:prompt => "Showings" %>
<%= select_tag ('seat_id'),
options_from_collection_for_select(#seats, :id, :seats_available, 0 ),
:prompt => "Seats" %>
<%= submit_tag 'Search' %>
film.rb:
class Film < ActiveRecord::Base
has_many :showings
belongs_to :certificate
belongs_to :category
def title_info
"#{title}"
end
end
seat.rb:
class Seat < ActiveRecord::Base
belongs_to :screen
has_many :bookings
def seats_available
"#{row_letter}#{row_number}"
end
end
showing.rb:
class Showing < ActiveRecord::Base
belongs_to :film
has_many :bookings
belongs_to :screen
def showing_times
"#{show_date.strftime("%e %b %Y")} # #{show_time.strftime("%H:%M")}"
end
end
But for some reason with the line: <%= select_tag ('title_id'),
options_from_collection_for_select(#films, :id, :title_info, 0 ),
:prompt => "Film" %> I get the error:
NoMethodError in Bookings#new
undefined method `map' for nil:NilClass
The weird part is that I am using a lot of this code else where, I have a _multi_search.html.erb form:
<%= form_tag my_path, :method=>'post', :multipart => true do %>
<!-- Genre: -->
Search By:
<%= select_tag ('cat_id'),
options_from_collection_for_select(#categories, :id, :category_info, 0 ),
:prompt => "Genre" %>
<%= select_tag ('cert_id'),
options_from_collection_for_select(#certificates, :id, :certificate_info, 0 ),
:prompt => "Age Rating" %>
<%= text_field_tag :search_string, nil, placeholder: "ACTOR" %>
or
<%= select_tag ('title_id'),
options_from_collection_for_select(#films, :id, :title_info, 0 ),
:prompt => "Film" %>
<%= submit_tag 'Search' %>
<% end %>
And is used in the application.html.erb:
<%= render(:partial => '/multi_search', :locals=> {:categories => #categories = existing_genres, :certificates => #certificates = Certificate.all, :films => #films = Film.all, :my_path => '/films/multi_find' }) %>
And that works fine.
What am I doing wrong?

Answer 1

It looks like #films is nil. Try setting #films = Film.all (instead of #film = Film.all) in _form.html.erb.
Update:
I would recommend moving the queries to the controller action. In the Model-View-Controller pattern, Controllers should be asking Models for data, not Views.
# BookingLookupController
def new
#films = Film.all
#showings = Showing.all
#seats = Seat.all
end
You can then reference the instance variables in the view.
<%= render partial: '/booking_lookup', locals: {films: #films, showings: #showings, seats: #seats, my_path: '/films/booking_lookup' } %>

Answer 2

In Controller, select fields as you just want to display names in dropdown
def method_name
#films = Film.select([:id, :title_info])
#showings = Showing.select([:id, :showing_times])
#seats = Seat.select([:id, :seats_available])
end
In page
<%= render(:partial => '/booking_lookup', :locals=> {:films => #films, :showings => #showings, :seats => #seats, :my_path => '/films/booking_lookup' }) %>
In partial
options_from_collection_for_select(films, :id, :title_info, 0 ),:prompt => "Film" %>