Ruby on Rails Class Variable not being referenced by controller - ruby-on-rails

Question

I have a small web app in Ruby on Rails which lists antique documents and the locations that are referenced by the documents. I can update locations that are already attached to documents, but when trying to create a new document, I get the following error
undefined method `locations' for nil:NilClass
The NilClass occurs in LocationController#new:
def new
#location = #document.locations.new
end
This is called from the view as such
<%= form_for(#location,:url=>new_document_location_path(#document)) do |f| %>
<%= render :partial => "document_locations/form", :locals =>{:f=>f} %>
<%= f.submit "Save",:class=>"span2 btn" %>
<%end%>
So for some reason, the #document class isn't being referenced by the controller. I know the class is accessible to the view and in scope as I am able to view document attributes within the form (eg <%= #document.id %>
So, why is the Controller not able to reference the #document variable? I'm assuming this is down to how I am passing the class variable. Eitherway, I'd be very grateful for some pointers.
This is how the models are defined
class Document < ActiveRecord::Base
has_many :locations, :dependent => :destroy
end
class Location < ActiveRecord::Base
belongs_to :document
end
Here's my routes
Pastpaper::Application.routes.draw do
# added in to test
match '/documents/:id/locations/create' => 'locations#create'
resources :documents do
collection do
match 'permanent_delete/:id' => 'documents#permanently_delete',:as => :permanent_delete
end
match '/authorinfo' => 'documents#authorinfo',:as => :authorinfo
match '/publicationinfo' => 'documents#publicationinfo',:as => :publicationinfo
match '/images' => 'documents#itemimages' ,:as => :itemimages
match '/locations' => 'documents#locations',:as => :locations
match '/itempeople' => 'documents#itempeople' ,:as => :itempeople
match '/people_facts_locations' => 'documents#people_facts_locations',:as => :people_facts_loc
resources :locations, :controller=>"locations"
resources :people ,:controller => "document_people"
resources :document_facts
resource :facts
resources :document_photos
end
resources :home do
collection do
get 'document_search','simple_location_search','date_search','simple_people_search','simple_organisation_search','document_filter'
get 'search_results'
post 'search_results'
end
end
match 'documents/publicationinfo/:id' => 'documents#publicationinfo',:as => :publicationinfo
match 'documents/update/publishinginfo/:id' => 'documents#publishinginfo',:as => :publishinginfo
match 'documents/document_image_remove/:id' => 'documents#remove_image',:as=>"remove_image"
match 'documents/make_primary_image/:id' => 'documents#make_primary_image',:as => :make_primary_image
match 'person_detail/:id' => 'documents#person_detail',:as=>'person_detail'
match 'about', :to=> 'pages#about'
match 'contact', :to => 'pages#contact'
match 'privacy', :to => 'pages#privacy'
match 'terms', :to => 'pages#terms'
match 'help', :to => 'pages#help'
namespace :admin do
resources :document_types
resources :statuses
resources :attribute_types
resources :event_types
resources :users
resources :orders
resources :documents
match 'restore_document/:id' => 'Documents#restore_document', :as => 'restore_document'
match 'report' => 'report#index' ,:as=>:report
match 'report/surname_report' => 'report#surname_report',:as=>:surname_report
match 'report/location_report' => 'report#location_report',:as=>:location_report
end
root :to => 'home#index'
end
And here's the relevant Controllers:
DocumentController
class DocumentsController < ApplicationController
before_filter :prepare_document ,:only => [:locations]
def locations
#locations = #document.locations.order("id asc")
#location = #document.locations.new
end
private
def prepare_document
if params[:id]
#document = Document.find(params[:id], :include => [:document_attributes])
elsif params[:document_id]
#document = Document.find(params[:document_id], :include => [:document_attributes])
end
end
end
LocationsController
class LocationsController < ApplicationController
before_filter :prepare_document
def new
#location = #document.locations.new
end
def create
#location = #document.locations.build
if #location.save
redirect_to document_locations_url(#document)
else
render "new"
end
end
def update
#location = #document.locations.find(params[:id])
if #location.update_attributes(params[:location])
redirect_to document_locations_url(#document)
else
render "edit"
end
end
def prepare_document
if params[:document_id]
if current_user.is_admin?
#document = Document.find(params[:document_id], :include => [:document_attributes])
else
#document = current_user.documents.find(params[:document_id], :include => [:document_attributes])
end
end
end
end
This is how my routes rake out
logout GET /logout(.:format) {:action=>"destroy", :controller=>"sessions"}
login POST /login(.:format) {:action=>"create", :controller=>"sessions"}
forgot_password /forgot_password(.:format) {:action=>"new", :controller=>"password_resets"}
user_home GET /profile(.:format) {:action=>"index", :controller=>"users"}
deactivateaccount /account/deactivate(.:format) {:controller=>"users", :action=>"accountdeactivate"}
changepassword /account/changepassword(.:format) {:controller=>"users", :action=>"changepassword"}
register /user/registration(.:format) {:controller=>"users", :action=>"new"}
users GET /users(.:format) {:action=>"index", :controller=>"users"}
POST /users(.:format) {:action=>"create", :controller=>"users"}
new_user GET /users/new(.:format) {:action=>"new", :controller=>"users"}
edit_user GET /users/:id/edit(.:format) {:action=>"edit", :controller=>"users"}
user GET /users/:id(.:format) {:action=>"show", :controller=>"users"}
PUT /users/:id(.:format) {:action=>"update", :controller=>"users"}
DELETE /users/:id(.:format) {:action=>"destroy", :controller=>"users"}
password_resets GET /password_resets(.:format) {:action=>"index", :controller=>"password_resets"}
POST /password_resets(.:format) {:action=>"create", :controller=>"password_resets"}
new_password_reset GET /password_resets/new(.:format) {:action=>"new", :controller=>"password_resets"}
edit_password_reset GET /password_resets/:id/edit(.:format) {:action=>"edit", :controller=>"password_resets"}
password_reset GET /password_resets/:id(.:format) {:action=>"show", :controller=>"password_resets"}
PUT /password_resets/:id(.:format) {:action=>"update", :controller=>"password_resets"}
DELETE /password_resets/:id(.:format) {:action=>"destroy", :controller=>"password_resets"}
password_reset_path /password_resets/:id/edit(.:format) {:controller=>"password_resets", :action=>"edit"}
/documents/:id/locations/create(.:format) {:controller=>"locations", :action=>"create"}
permanent_delete_documents /documents/permanent_delete/:id(.:format) {:controller=>"documents", :action=>"permanently_delete"}
document_authorinfo /documents/:document_id/authorinfo(.:format) {:controller=>"documents", :action=>"authorinfo"}
document_publicationinfo /documents/:document_id/publicationinfo(.:format) {:controller=>"documents", :action=>"publicationinfo"}
document_itemimages /documents/:document_id/images(.:format) {:controller=>"documents", :action=>"itemimages"}
document_locations /documents/:document_id/locations(.:format) {:controller=>"documents", :action=>"locations"}
document_itempeople /documents/:document_id/itempeople(.:format) {:controller=>"documents", :action=>"itempeople"}
document_people_facts_loc /documents/:document_id/people_facts_locations(.:format) {:controller=>"documents", :action=>"people_facts_locations"}
GET /documents/:document_id/locations(.:format) {:action=>"index", :controller=>"locations"}
POST /documents/:document_id/locations(.:format) {:action=>"create", :controller=>"locations"}
new_document_location GET /documents/:document_id/locations/new(.:format) {:action=>"new", :controller=>"locations"}
edit_document_location GET /documents/:document_id/locations/:id/edit(.:format) {:action=>"edit", :controller=>"locations"}
document_location GET /documents/:document_id/locations/:id(.:format) {:action=>"show", :controller=>"locations"}
PUT /documents/:document_id/locations/:id(.:format) {:action=>"update", :controller=>"locations"}
DELETE /documents/:document_id/locations/:id(.:format) {:action=>"destroy", :controller=>"locations"}
document_people GET /documents/:document_id/people(.:format) {:action=>"index", :controller=>"document_people"}
POST /documents/:document_id/people(.:format) {:action=>"create", :controller=>"document_people"}
new_document_person GET /documents/:document_id/people/new(.:format) {:action=>"new", :controller=>"document_people"}
edit_document_person GET /documents/:document_id/people/:id/edit(.:format) {:action=>"edit", :controller=>"document_people"}
document_person GET /documents/:document_id/people/:id(.:format) {:action=>"show", :controller=>"document_people"}
PUT /documents/:document_id/people/:id(.:format) {:action=>"update", :controller=>"document_people"}
DELETE /documents/:document_id/people/:id(.:format) {:action=>"destroy", :controller=>"document_people"}
document_document_facts GET /documents/:document_id/document_facts(.:format) {:action=>"index", :controller=>"document_facts"}
POST /documents/:document_id/document_facts(.:format) {:action=>"create", :controller=>"document_facts"}
new_document_document_fact GET /documents/:document_id/document_facts/new(.:format) {:action=>"new", :controller=>"document_facts"}
edit_document_document_fact GET /documents/:document_id/document_facts/:id/edit(.:format) {:action=>"edit", :controller=>"document_facts"}
document_document_fact GET /documents/:document_id/document_facts/:id(.:format) {:action=>"show", :controller=>"document_facts"}
PUT /documents/:document_id/document_facts/:id(.:format) {:action=>"update", :controller=>"document_facts"}
DELETE /documents/:document_id/document_facts/:id(.:format) {:action=>"destroy", :controller=>"document_facts"}
document_facts POST /documents/:document_id/facts(.:format) {:action=>"create", :controller=>"facts"}
new_document_facts GET /documents/:document_id/facts/new(.:format) {:action=>"new", :controller=>"facts"}
edit_document_facts GET /documents/:document_id/facts/edit(.:format) {:action=>"edit", :controller=>"facts"}
GET /documents/:document_id/facts(.:format) {:action=>"show", :controller=>"facts"}
PUT /documents/:document_id/facts(.:format) {:action=>"update", :controller=>"facts"}
DELETE /documents/:document_id/facts(.:format) {:action=>"destroy", :controller=>"facts"}
document_document_photos GET /documents/:document_id/document_photos(.:format) {:action=>"index", :controller=>"document_photos"}
POST /documents/:document_id/document_photos(.:format) {:action=>"create", :controller=>"document_photos"}
new_document_document_photo GET /documents/:document_id/document_photos/new(.:format) {:action=>"new", :controller=>"document_photos"}
edit_document_document_photo GET /documents/:document_id/document_photos/:id/edit(.:format) {:action=>"edit", :controller=>"document_photos"}
document_document_photo GET /documents/:document_id/document_photos/:id(.:format) {:action=>"show", :controller=>"document_photos"}
PUT /documents/:document_id/document_photos/:id(.:format) {:action=>"update", :controller=>"document_photos"}
DELETE /documents/:document_id/document_photos/:id(.:format) {:action=>"destroy", :controller=>"document_photos"}
documents GET /documents(.:format) {:action=>"index", :controller=>"documents"}
POST /documents(.:format) {:action=>"create", :controller=>"documents"}
new_document GET /documents/new(.:format) {:action=>"new", :controller=>"documents"}
edit_document GET /documents/:id/edit(.:format) {:action=>"edit", :controller=>"documents"}
document GET /documents/:id(.:format) {:action=>"show", :controller=>"documents"}
PUT /documents/:id(.:format) {:action=>"update", :controller=>"documents"}
DELETE /documents/:id(.:format) {:action=>"destroy", :controller=>"documents"}
paypal_cancel /payments/cancel(.:format) {:controller=>"payments", :action=>"paypal_cancel"}
paypal_return /payments/success(.:format) {:controller=>"payments", :action=>"paypal_return"}
paypal_ipn /payments/ipn(.:format) {:controller=>"payments", :action=>"create"}
document_search_home_index GET /home/document_search(.:format) {:action=>"document_search", :controller=>"home"}
simple_location_search_home_index GET /home/simple_location_search(.:format) {:action=>"simple_location_search", :controller=>"home"}
date_search_home_index GET /home/date_search(.:format) {:action=>"date_search", :controller=>"home"}
simple_people_search_home_index GET /home/simple_people_search(.:format) {:action=>"simple_people_search", :controller=>"home"}
simple_organisation_search_home_index GET /home/simple_organisation_search(.:format) {:action=>"simple_organisation_search", :controller=>"home"}
document_filter_home_index GET /home/document_filter(.:format) {:action=>"document_filter", :controller=>"home"}
search_results_home_index GET /home/search_results(.:format) {:action=>"search_results", :controller=>"home"}
POST /home/search_results(.:format) {:action=>"search_results", :controller=>"home"}
home_index GET /home(.:format) {:action=>"index", :controller=>"home"}
POST /home(.:format) {:action=>"create", :controller=>"home"}
new_home GET /home/new(.:format) {:action=>"new", :controller=>"home"}
edit_home GET /home/:id/edit(.:format) {:action=>"edit", :controller=>"home"}
home GET /home/:id(.:format) {:action=>"show", :controller=>"home"}
PUT /home/:id(.:format) {:action=>"update", :controller=>"home"}
DELETE /home/:id(.:format) {:action=>"destroy", :controller=>"home"}
publicationinfo /documents/publicationinfo/:id(.:format) {:controller=>"documents", :action=>"publicationinfo"}
publishinginfo /documents/update/publishinginfo/:id(.:format) {:controller=>"documents", :action=>"publishinginfo"}
remove_image /documents/document_image_remove/:id(.:format) {:controller=>"documents", :action=>"remove_image"}
make_primary_image /documents/make_primary_image/:id(.:format) {:controller=>"documents", :action=>"make_primary_image"}
person_detail /person_detail/:id(.:format) {:controller=>"documents", :action=>"person_detail"}
about /about(.:format) {:action=>"about", :controller=>"pages"}
contact /contact(.:format) {:action=>"contact", :controller=>"pages"}
privacy /privacy(.:format) {:action=>"privacy", :controller=>"pages"}
terms /terms(.:format) {:action=>"terms", :controller=>"pages"}
help /help(.:format) {:action=>"help", :controller=>"pages"}

Answer 1

def new
#location = #document.locations.build
end
Use build not new. And make your prepare_document private in your controller.
Also
<%= form_for([#document, #location]) do |f| %>
Your url parameter was wrong, you shouldn't post forms to the new action, you should post them to the update action like I showed above.